use prolog_parser::ast::parsing_stream;

use prolog::heap_print::*;
use prolog::machine::compile::*;
use prolog::machine::machine_errors::*;
use prolog::machine::machine_indices::*;
use prolog::machine::toplevel::*;
use prolog::machine::*;
use prolog::read::readline;

use indexmap::IndexSet;

use std::mem::swap;
use std::ops::{Range, RangeFrom};

pub struct TestOutputter {
    results: Vec<IndexSet<String>>,
    contents: IndexSet<String>,
    focus: String,
}

impl TestOutputter {
    fn cache(&mut self) {
        self.begin_new_var();

        let mut contents = IndexSet::new();
        swap(&mut contents, &mut self.contents);

        self.results.push(contents);
    }
}

impl HCValueOutputter for TestOutputter {
    type Output = Vec<IndexSet<String>>;

    fn new() -> Self {
        TestOutputter {
            results: vec![],
            contents: IndexSet::new(),
            focus: String::new(),
        }
    }

    fn append(&mut self, focus: &str) {
        self.focus += focus;
    }

    fn push_char(&mut self, c: char) {
        self.focus.push(c);
    }

    fn begin_new_var(&mut self) {
        if !self.focus.is_empty() {
            let mut focus = String::new();
            swap(&mut focus, &mut self.focus);

            self.contents.insert(focus);
        }
    }

    fn insert(&mut self, idx: usize, c: char) {
        self.focus.insert(idx, c);
    }

    fn result(self) -> Self::Output {
        self.results
    }

    fn ends_with(&self, s: &str) -> bool {
        self.focus.ends_with(s)
    }

    fn len(&self) -> usize {
        self.focus.len()
    }

    fn truncate(&mut self, len: usize) {
        self.focus.truncate(len);
    }

    fn range(&self, index: Range<usize>) -> &str {
        &self.focus.as_str()[index]
    }

    fn range_from(&self, index: RangeFrom<usize>) -> &str {
        &self.focus.as_str()[index]
    }
}

pub fn collect_test_output(wam: &mut Machine, alloc_locs: AllocVarDict) -> Vec<IndexSet<String>> {
    let mut output = TestOutputter::new();

    output = wam.test_heap_view(output);
    output.cache();

    while let EvalSession::SubsequentQuerySuccess = wam.continue_query(&alloc_locs) {
        output = wam.test_heap_view(output);
        output.cache();
    }

    output.result()
}

pub fn collect_test_output_with_limit(
    wam: &mut Machine,
    alloc_locs: AllocVarDict,
    limit: usize,
) -> Vec<IndexSet<String>> {
    let mut output = TestOutputter::new();

    output = wam.test_heap_view(output);
    output.cache();

    let mut count = 1;

    if count == limit {
        return output.result();
    }

    while let EvalSession::SubsequentQuerySuccess = wam.continue_query(&alloc_locs) {
        output = wam.test_heap_view(output);
        output.cache();

        count += 1;

        if count == limit {
            break;
        }
    }

    output.result()
}

#[allow(dead_code)]
pub fn submit(wam: &mut Machine, buffer: &str) -> bool {
    wam.reset();

    match submit_code(wam, buffer) {
        EvalSession::InitialQuerySuccess(_)
        | EvalSession::EntrySuccess
        | EvalSession::SubsequentQuerySuccess => true,
        _ => false,
    }
}

#[allow(dead_code)]
pub fn submit_query(wam: &mut Machine, buffer: &str, result: Vec<IndexSet<String>>) -> bool {
    wam.reset();

    match stream_to_toplevel(parsing_stream(buffer.as_bytes()), wam) {
        Ok(term) => match compile_term(wam, term) {
            EvalSession::InitialQuerySuccess(alloc_locs) => {
                result == collect_test_output(wam, alloc_locs)
            }
            EvalSession::EntrySuccess => true,
            _ => false,
        },
        Err(_) => panic!("syntax error"),
    }
}

#[allow(dead_code)]
pub fn submit_query_without_results(wam: &mut Machine, buffer: &str) -> bool {
    wam.reset();

    match stream_to_toplevel(parsing_stream(buffer.as_bytes()), wam) {
        Ok(term) => match compile_term(wam, term) {
            EvalSession::InitialQuerySuccess(..) | EvalSession::EntrySuccess => true,
            _ => false,
        },
        Err(_) => panic!("syntax error"),
    }
}

#[allow(dead_code)]
pub fn submit_query_with_limit(
    wam: &mut Machine,
    buffer: &str,
    result: Vec<IndexSet<String>>,
    limit: usize,
) -> bool {
    wam.reset();

    match stream_to_toplevel(parsing_stream(buffer.as_bytes()), wam) {
        Ok(term) => match compile_term(wam, term) {
            EvalSession::InitialQuerySuccess(alloc_locs) => {
                result == collect_test_output_with_limit(wam, alloc_locs, limit)
            }
            EvalSession::EntrySuccess => true,
            _ => false,
        },
        Err(_) => panic!("syntax_error"),
    }
}

#[allow(dead_code)]
pub fn submit_code(wam: &mut Machine, buf: &str) -> EvalSession {
    compile_user_module(wam, parsing_stream(buf.as_bytes()), true)
}

#[allow(unused_macros)]
macro_rules! expand_strs {
    ($arr:expr) => {
        $arr.into_iter().map(|s| String::from(*s)).collect()
    };
}

#[allow(unused_macros)]
macro_rules! assert_prolog_success_with_limit {
    ($wam:expr, $buf:expr, [$($res:expr),*], $limit:expr) => (
        assert!(submit_query_with_limit($wam, $buf, vec![$(expand_strs!($res)),*], $limit))
    )
}

#[allow(unused_macros)]
macro_rules! assert_prolog_failure {
    ($wam: expr, $buf: expr) => {
        assert_eq!(submit_query_without_results($wam, $buf), false)
    };
}

#[allow(unused_macros)]
macro_rules! assert_prolog_success {
    ($wam:expr, $query:expr, [$($res:expr),*]) => (
        assert!(submit_query($wam, $query, vec![$(expand_strs!($res)),*]))
    );
    ($wam:expr, $buf:expr) => (
        assert_eq!(submit_query_without_results($wam, $buf), true)
    )
}

#[test]
fn test_queries_on_facts() {
    let mut wam = Machine::new(readline::input_stream());

    submit(&mut wam, "p(Z, Z).");
    submit(&mut wam, "clouds(are, nice).");

    assert_prolog_success!(&mut wam, "p(Z, Z).", [["Z = _0"]]);
    assert_prolog_success!(&mut wam, "p(Z, z).", [["Z = z"]]);
    assert_prolog_success!(&mut wam, "p(Z, w).", [["Z = w"]]);

    assert_prolog_failure!(&mut wam, "p(z, w).");

    assert_prolog_success!(&mut wam, "p(w, w).");

    assert_prolog_failure!(&mut wam, "clouds(Z, Z).");

    assert_prolog_success!(&mut wam, "clouds(are, Z).", [["Z = nice"]]);
    assert_prolog_success!(&mut wam, "clouds(Z, nice).", [["Z = are"]]);

    submit(&mut wam, "p(Z, h(Z, W), f(W)).");

    assert_prolog_failure!(&mut wam, "p(z, h(z, z), f(w)).");
    assert_prolog_success!(&mut wam, "p(z, h(z, w), f(w)).");
    assert_prolog_success!(&mut wam, "p(z, h(z, W), f(w)).", [["W = w"]]);
    assert_prolog_success!(&mut wam, "p(Z, h(Z, w), f(Z)).", [["Z = w"]]);
    assert_prolog_failure!(&mut wam, "p(z, h(Z, w), f(Z)).");

    submit(&mut wam, "p(f(X), h(Y, f(a)), Y).");

    assert_prolog_success!(
        &mut wam,
        "p(Z, h(Z, W), f(W)).",
        [["W = f(a)", "Z = f(f(a))"]]
    );
}

#[test]
fn test_queries_on_rules() {
    let mut wam = Machine::new(readline::input_stream());

    submit(&mut wam, "p(X, Y) :- q(X, Z), r(Z, Y).");
    submit(&mut wam, "q(q, s).");
    submit(&mut wam, "r(s, t).");

    assert_prolog_success!(&mut wam, "p(X, Y).", [["Y = t", "X = q"]]);
    assert_prolog_success!(&mut wam, "p(q, t).");
    assert_prolog_failure!(&mut wam, "p(t, q).");
    assert_prolog_success!(&mut wam, "p(q, T).", [["T = t"]]);
    assert_prolog_failure!(&mut wam, "p(t, t).");

    submit(&mut wam, "p(X, Y) :- q(f(f(X)), R), r(S, T).");
    submit(&mut wam, "q(f(f(X)), r).");

    assert_prolog_success!(&mut wam, "p(X, Y).", [["X = _0", "Y = _1"]]);

    submit(&mut wam, "q(f(f(x)), r).");

    assert_prolog_success!(&mut wam, "p(X, Y).", [["X = x", "Y = _1"]]);

    submit(&mut wam, "p(X, Y) :- q(X, Y), r(X, Y).");
    submit(&mut wam, "q(s, t).");
    submit(&mut wam, "r(X, Y) :- r(a).");
    submit(&mut wam, "r(a).");

    assert_prolog_success!(&mut wam, "p(X, Y).", [["X = s", "Y = t"]]);
    assert_prolog_failure!(&mut wam, "p(t, S).");
    assert_prolog_success!(&mut wam, "p(s, T).", [["T = t"]]);
    assert_prolog_success!(&mut wam, "p(S, t).", [["S = s"]]);

    submit(&mut wam, "p(f(f(a), g(b), X), g(b), h) :- q(X, Y).");
    submit(&mut wam, "q(X, Y).");

    assert_prolog_success!(
        &mut wam,
        "p(f(X, Y, Z), g(b), h).",
        [["Z = _3", "Y = g(b)", "X = f(a)"]]
    );
    assert_prolog_failure!(&mut wam, "p(f(X, g(Y), Z), g(Z), X).");
    assert_prolog_success!(
        &mut wam,
        "p(f(X, g(Y), Z), g(Z), h).",
        [["Z = b", "Y = b", "X = f(a)"]]
    );
    assert_prolog_success!(
        &mut wam,
        "p(Z, Y, X).",
        [["X = h", "Y = g(b)", "Z = f(f(a),g(b),_7)"]]
    );
    assert_prolog_success!(
        &mut wam,
        "p(f(X, Y, Z), Y, h).",
        [["Y = g(b)", "Z = _3", "X = f(a)"]]
    );

    submit(&mut wam, "p(_, f(_, Y, _)) :- h(Y).");
    submit(&mut wam, "h(y).");

    assert_prolog_success!(&mut wam, "p(_, f(_, Y, _)).", [["Y = y"]]);
    assert_prolog_success!(&mut wam, "p(_, f(_, y, _)).");
    assert_prolog_failure!(&mut wam, "p(_, f(_, z, _)).");
}

#[test]
fn test_queries_on_predicates() {
    let mut wam = Machine::new(readline::input_stream());

    submit(&mut wam, "p(X, a). p(b, X).");

    assert_prolog_success!(&mut wam, "p(x, Y).", [["Y = a"]]);
    assert_prolog_success!(
        &mut wam,
        "p(X, a).",
        [
            ["X = _0"], // 1st case
            ["X = b"]
        ]
    ); // 2nd case.
    assert_prolog_success!(
        &mut wam,
        "p(b, X).",
        [
            ["X = a"], // 1st case
            ["X = _0"]
        ]
    ); // 2nd case.
    assert_prolog_success!(&mut wam, "p(X, X).", [["X = a"], ["X = b"]]);
    assert_prolog_success!(&mut wam, "p(b, a).");
    assert_prolog_failure!(&mut wam, "p(a, b).");

    submit(&mut wam, "p(X, Y, a). p(X, a, Y). p(X, Y, a).");

    assert_prolog_success!(&mut wam, "p(c, d, X).", [["X = a"], ["X = a"]]);
    assert_prolog_success!(&mut wam, "p(a, a, a).");
    assert_prolog_failure!(&mut wam, "p(b, c, d).");

    submit(&mut wam, "p(X, a). p(X, Y) :- q(Z), p(X, X).");

    assert_prolog_success!(&mut wam, "p(X, Y).", [["X = _0", "Y = a"]]);
    assert_prolog_success!(&mut wam, "p(x, a).");
    assert_prolog_success!(&mut wam, "p(X, a).", [["X = _0"]]);
    assert_prolog_failure!(&mut wam, "p(X, b).");

    submit(&mut wam, "q(z).");

    assert_prolog_success_with_limit!(&mut wam, "p(X, b).", [["X = a"], ["X = a"], ["X = a"]], 3);
    assert_prolog_success!(&mut wam, "p(x, a).");
    assert_prolog_success_with_limit!(
        &mut wam,
        "p(X, Y).",
        [
            ["X = _0", "Y = a"],
            ["Y = _1", "X = a"],
            ["Y = _1", "X = a"]
        ],
        3
    );

    submit(&mut wam, "p(X, a). p(X, Y) :- q(Y), p(X, X).");

    assert_prolog_success_with_limit!(
        &mut wam,
        "p(X, Y).",
        [["X = _0", "Y = a"], ["Y = z", "X = a"]],
        2
    );
    assert_prolog_failure!(&mut wam, "p(X, b).");

    submit(&mut wam, "p(a, z). p(X, Y) :- q(Y), p(X, Y).");

    assert_prolog_success_with_limit!(
        &mut wam,
        "p(X, Y).",
        [["X = a", "Y = z"], ["X = a", "Y = z"]],
        2
    );

    assert_prolog_success_with_limit!(&mut wam, "p(X, z).", [["X = a"], ["X = a"]], 2);
    assert_prolog_success!(&mut wam, "p(a, z).");
    assert_prolog_success_with_limit!(&mut wam, "p(a, X).", [["X = z"], ["X = z"]], 2);
    assert_prolog_failure!(&mut wam, "p(b, a).");

    submit(
        &mut wam,
        "p(X, Y, Z) :- q(X), r(Y), s(Z).
                      p(a, b, Z) :- q(Z).",
    );

    submit(&mut wam, "q(x).");
    submit(&mut wam, "r(y).");
    submit(&mut wam, "s(z).");

    assert_prolog_success!(
        &mut wam,
        "p(X, Y, Z).",
        [["Y = y", "X = x", "Z = z"], ["Y = b", "X = a", "Z = x"]]
    );
    assert_prolog_failure!(&mut wam, "p(a, b, c).");
    assert_prolog_success!(&mut wam, "p(a, b, C).", [["C = x"]]);

    submit(&mut wam, "p(X) :- r(X).");
    submit(&mut wam, "r(X) :- s(X, t). r(X) :- t(X, u).");

    submit(&mut wam, "s(x, t).");
    submit(&mut wam, "t(y, u).");

    assert_prolog_success!(&mut wam, "p(X).", [["X = x"], ["X = y"]]);
    assert_prolog_success!(&mut wam, "p(x).");
    assert_prolog_success!(&mut wam, "p(y).");
    assert_prolog_failure!(&mut wam, "p(z).");

    submit(
        &mut wam,
        "p(f(f(X)), h(W), Y) :- g(W), h(W), f(X).
                      p(X, Y, Z) :- h(Y), g(W), z(Z).",
    );
    submit(&mut wam, "g(f(X)) :- z(X). g(X) :- h(X).");
    submit(&mut wam, "h(w). h(x). h(z).");
    submit(&mut wam, "f(s).");
    submit(&mut wam, "z(Z).");

    assert_prolog_success!(
        &mut wam,
        "p(X, Y, Z).",
        [
            ["Y = h(w)", "X = f(f(s))", "Z = _2"],
            ["Y = h(x)", "X = f(f(s))", "Z = _2"],
            ["Y = h(z)", "X = f(f(s))", "Z = _2"],
            ["Y = w", "Z = _2", "X = _0"],
            ["Y = w", "Z = _2", "X = _0"],
            ["Y = w", "Z = _2", "X = _0"],
            ["Y = w", "Z = _2", "X = _0"],
            ["Y = x", "Z = _2", "X = _0"],
            ["Y = x", "Z = _2", "X = _0"],
            ["Y = x", "Z = _2", "X = _0"],
            ["Y = x", "Z = _2", "X = _0"],
            ["Y = z", "Z = _2", "X = _0"],
            ["Y = z", "Z = _2", "X = _0"],
            ["Y = z", "Z = _2", "X = _0"],
            ["Y = z", "Z = _2", "X = _0"]
        ]
    );
    assert_prolog_success!(
        &mut wam,
        "p(X, X, Z).",
        [
            ["Z = _1", "X = w"],
            ["Z = _1", "X = w"],
            ["Z = _1", "X = w"],
            ["Z = _1", "X = w"],
            ["Z = _1", "X = x"],
            ["Z = _1", "X = x"],
            ["Z = _1", "X = x"],
            ["Z = _1", "X = x"],
            ["Z = _1", "X = z"],
            ["Z = _1", "X = z"],
            ["Z = _1", "X = z"],
            ["Z = _1", "X = z"]
        ]
    );
    assert_prolog_success!(
        &mut wam,
        "p(f(f(Z)), Y, Z).",
        [
            ["Y = h(w)", "Z = s"],
            ["Y = h(x)", "Z = s"],
            ["Y = h(z)", "Z = s"],
            ["Y = w", "Z = _1"],
            ["Y = w", "Z = _1"],
            ["Y = w", "Z = _1"],
            ["Y = w", "Z = _1"],
            ["Y = x", "Z = _1"],
            ["Y = x", "Z = _1"],
            ["Y = x", "Z = _1"],
            ["Y = x", "Z = _1"],
            ["Y = z", "Z = _1"],
            ["Y = z", "Z = _1"],
            ["Y = z", "Z = _1"],
            ["Y = z", "Z = _1"]
        ]
    );
    assert_prolog_success!(
        &mut wam,
        "p(X, X, X).",
        [
            ["X = w"],
            ["X = w"],
            ["X = w"],
            ["X = w"],
            ["X = x"],
            ["X = x"],
            ["X = x"],
            ["X = x"],
            ["X = z"],
            ["X = z"],
            ["X = z"],
            ["X = z"]
        ]
    );
    assert_prolog_success!(
        &mut wam,
        "p(X, Y, X).",
        [
            ["Y = h(w)", "X = f(f(s))"],
            ["Y = h(x)", "X = f(f(s))"],
            ["Y = h(z)", "X = f(f(s))"],
            ["Y = w", "X = _0"],
            ["Y = w", "X = _0"],
            ["Y = w", "X = _0"],
            ["Y = w", "X = _0"],
            ["Y = x", "X = _0"],
            ["Y = x", "X = _0"],
            ["Y = x", "X = _0"],
            ["Y = x", "X = _0"],
            ["Y = z", "X = _0"],
            ["Y = z", "X = _0"],
            ["Y = z", "X = _0"],
            ["Y = z", "X = _0"]
        ]
    );
    assert_prolog_failure!(&mut wam, "p(f(f(X)), h(f(X)), Y).");

    submit(&mut wam, "p(X) :- f(Y), g(Y), i(X, Y).");
    submit(&mut wam, "g(f(a)). g(f(b)). g(f(c)).");
    submit(&mut wam, "f(f(a)). f(f(b)). f(f(c)).");
    submit(&mut wam, "i(X, X).");

    assert_prolog_success!(
        &mut wam,
        "p(X).",
        [["X = f(a)"], ["X = f(b)"], ["X = f(c)"]]
    );

    submit(&mut wam, "p(X) :- f(f(Y)), g(Y, f(Y)), i(X, f(Y)).");
    submit(&mut wam, "g(Y, f(Y)) :- g(f(Y)).");

    assert_prolog_success!(
        &mut wam,
        "p(X).",
        [["X = f(a)"], ["X = f(b)"], ["X = f(c)"]]
    );
}

#[test]
fn test_queries_on_cuts() {
    let mut wam = Machine::new(readline::input_stream());

    // test shallow cuts.
    submit(
        &mut wam,
        "memberchk(X, [X|_]) :- !.
                      memberchk(X, [_|Xs]) :- memberchk(X, Xs).",
    );

    assert_prolog_success!(&mut wam, "memberchk(X, [a,b,c]).", [["X = a"]]);
    assert_prolog_success!(
        &mut wam,
        "memberchk([X,X], [a,b,c,[d,e],[d,d]]).",
        [["X = d"]]
    );
    assert_prolog_success!(
        &mut wam,
        "memberchk([X,X], [a,b,c,[D,d],[e,e]]).",
        [["X = d", "D = d"]]
    );
    assert_prolog_failure!(&mut wam, "memberchk([X,X], [a,b,c,[e,d],[f,e]]).");
    assert_prolog_failure!(&mut wam, "memberchk([X,X,Y], [a,b,c,[e,d],[f,e]]).");
    assert_prolog_success!(
        &mut wam,
        "memberchk([X,X,Y], [a,b,c,[e,e,d],[f,e]]).",
        [["X = e", "Y = d"]]
    );

    // test deep cuts.
    submit(&mut wam, "commit :- a, !.");

    assert_prolog_failure!(&mut wam, "commit.");

    submit(&mut wam, "a.");

    assert_prolog_success!(&mut wam, "commit.");

    submit(&mut wam, "commit(X) :- a(X), !.");

    assert_prolog_failure!(&mut wam, "commit(X).");

    submit(&mut wam, "a(x).");

    assert_prolog_success!(&mut wam, "commit(X).", [["X = x"]]);

    submit(&mut wam, "a :- b, !, c. a :- d.");

    assert_prolog_failure!(&mut wam, "a.");

    submit(&mut wam, "b.");

    assert_prolog_failure!(&mut wam, "a.");

    submit(&mut wam, "d.");

    // we've committed to the first clause since the query on b
    // succeeds, so we expect failure here.
    assert_prolog_failure!(&mut wam, "a.");

    submit(&mut wam, "c.");

    assert_prolog_success!(&mut wam, "a.");

    submit(&mut wam, "a(X) :- b, !, c(X). a(X) :- d(X).");

    assert_prolog_failure!(&mut wam, "a(X).");

    submit(&mut wam, "c(c).");
    submit(&mut wam, "d(d).");

    assert_prolog_success!(&mut wam, "a(X).", [["X = c"]]);

    submit(&mut wam, "b.");

    assert_prolog_success!(&mut wam, "a(X).", [["X = c"]]);
}

#[test]
fn test_queries_on_lists() {
    let mut wam = Machine::new(readline::input_stream());

    submit(&mut wam, "p([Z, W]).");

    assert_prolog_success!(&mut wam, "p([Z, Z]).", [["Z = _0"]]);
    assert_prolog_failure!(&mut wam, "p([Z, W, Y]).");
    assert_prolog_success!(&mut wam, "p([Z | W]).", [["Z = _0", "W = [_3]"]]);
    assert_prolog_success!(&mut wam, "p([Z | [Z]]).", [["Z = _0"]]);
    assert_prolog_success!(&mut wam, "p([Z | [W]]).", [["Z = _2", "W = _0"]]);
    assert_prolog_failure!(&mut wam, "p([Z | []]).");

    submit(&mut wam, "p([Z, Z]).");

    assert_prolog_success!(&mut wam, "p([Z, Z]).", [["Z = _0"]]);
    assert_prolog_failure!(&mut wam, "p([Z, W, Y]).");
    assert_prolog_success!(&mut wam, "p([Z | W]).", [["Z = _0", "W = [_0]"]]);
    assert_prolog_success!(&mut wam, "p([Z | [Z]]).", [["Z = _0"]]);
    assert_prolog_success!(&mut wam, "p([Z | [W]]).", [["Z = _0", "W = _0"]]);
    assert_prolog_failure!(&mut wam, "p([Z | []]).");

    submit(&mut wam, "p([Z]).");

    assert_prolog_failure!(&mut wam, "p([Z, Z]).");
    assert_prolog_failure!(&mut wam, "p([Z, W, Y]).");
    assert_prolog_success!(&mut wam, "p([Z | W]).", [["W = []", "Z = _0"]]);
    assert_prolog_failure!(&mut wam, "p([Z | [Z]]).");
    assert_prolog_failure!(&mut wam, "p([Z | [W]]).");
    assert_prolog_success!(&mut wam, "p([Z | []]).", [["Z = _0"]]);

    submit(
        &mut wam,
        "member(X, [X|_]).
                      member(X, [_|Xs]) :- member(X, Xs).",
    );

    assert_prolog_failure!(&mut wam, "member(a, [c, [X, Y]]).");
    assert_prolog_failure!(&mut wam, "member(c, [a, [X, Y]]).");
    assert_prolog_success!(&mut wam, "member(a, [a, [X, Y]]).", [["X = _2", "Y = _0"]]);

    assert_prolog_success!(
        &mut wam,
        "member(a, [X, Y, Z]).",
        [
            ["Y = _2", "X = a", "Z = _0"],
            ["Y = a", "X = _4", "Z = _0"],
            ["Y = _2", "X = _4", "Z = a"]
        ]
    );

    assert_prolog_success!(
        &mut wam,
        "member([X, X], [a, [X, Y]]).",
        [["X = _0", "Y = _0"]]
    );
    assert_prolog_success!(
        &mut wam,
        "member([X, X], [a, [b, c], [b, b], [Z, x], [d, f]]).",
        [["Z = _14", "X = b"], ["Z = x", "X = x"]]
    );
    assert_prolog_failure!(
        &mut wam,
        "member([X, X], [a, [b, c], [b, d], [foo, x], [d, f]])."
    );
    assert_prolog_success!(
        &mut wam,
        "member([X, Y], [a, [b, c], [b, b], [Z, x], [d, f]]).",
        [
            ["X = b", "Y = c", "Z = _14"],
            ["X = b", "Y = b", "Z = _14"],
            ["X = _2", "Y = x", "Z = _2"],
            ["X = d", "Y = f", "Z = _14"]
        ]
    );
    assert_prolog_failure!(
        &mut wam,
        "member([X, Y, Y], [a, [b, c], [b, b], [Z, x], [d, f]])."
    );
    assert_prolog_failure!(
        &mut wam,
        "member([X, Y, Z], [a, [b, c], [b, b], [Z, x], [d, f]])."
    );
}

#[test]
fn test_queries_on_conjuctive_queries() {
    let mut wam = Machine::new(readline::input_stream());

    submit(&mut wam, "p(a, b).");
    submit(&mut wam, "q(b, c).");

    assert_prolog_success!(&mut wam, "p(X, Y), q(Y, Z).", [["X = a", "Z = c", "Y = b"]]);
    assert_prolog_failure!(&mut wam, "p(X, Y), q(Y, X).");

    submit(&mut wam, "p(a, [f(g(X))]).");
    submit(&mut wam, "q(Y, c).");

    assert_prolog_success!(
        &mut wam,
        "p(X, Y), q(Y, Z).",
        [["Y = [f(g(_9))]", "X = a", "Z = c"]]
    );
    assert_prolog_failure!(&mut wam, "p(X, Y), q(Y, X).");

    submit(
        &mut wam,
        "member(X, [X|_]).
                      member(X, [_|Xs]) :- member(X, Xs).",
    );

    assert_prolog_success!(
        &mut wam,
        "member(X, [a,b,c]), member(X, [a,b,c]).",
        [["X = a"], ["X = b"], ["X = c"]]
    );
    assert_prolog_success!(
        &mut wam,
        "member(X, [a,b,c]), member(X, [b,c]).",
        [["X = b"], ["X = c"]]
    );
    assert_prolog_success!(&mut wam, "member(X, [a,c]), member(X, [b,c]).", [["X = c"]]);
    assert_prolog_success!(
        &mut wam,
        "member(X, [a,b,c,d]), !, member(X, [a,d]).",
        [["X = a"]]
    );
    assert_prolog_failure!(&mut wam, "member(X, [a,b,c,d]), !, member(X, [e]).");
    assert_prolog_success!(
        &mut wam,
        "member([X,X],[a,b,c,[d,d],[e,d]]),
                                         member(X, [a,b,c,d,e,f,g]),
                                         member(Y, [X, a, b, c, d]).",
        [
            ["X = d", "Y = d"],
            ["X = d", "Y = a"],
            ["X = d", "Y = b"],
            ["X = d", "Y = c"],
            ["X = d", "Y = d"]
        ]
    );

    submit(&mut wam, "p(a, [f(g(X))]). p(X, c) :- c.");
    submit(&mut wam, "c.");
    submit(&mut wam, "q(Y, c).");

    assert_prolog_success!(
        &mut wam,
        "p(X, Y), q(Y, Z).",
        [
            ["X = a", "Z = c", "Y = [f(g(_9))]"],
            ["X = _0", "Z = c", "Y = c"]
        ]
    );
    assert_prolog_success!(
        &mut wam,
        "p(X, Y), !, q(Y, Z).",
        [["Z = c", "Y = [f(g(_9))]", "X = a"]]
    );

    submit(
        &mut wam,
        "q([f(g(x))], Z). q([f(g(y))], Y). q([f(g(z))], a).",
    );

    assert_prolog_success!(
        &mut wam,
        "p(X, Y), q(Y, Z).",
        [
            ["Z = _11", "X = a", "Y = [f(g(x))]"],
            ["Z = _11", "X = a", "Y = [f(g(y))]"],
            ["Z = a", "X = a", "Y = [f(g(z))]"]
        ]
    );
    assert_prolog_success!(
        &mut wam,
        "p(X, Y), !, q(Y, Z).",
        [
            ["X = a", "Y = [f(g(x))]", "Z = _11"],
            ["X = a", "Y = [f(g(y))]", "Z = _11"],
            ["X = a", "Y = [f(g(z))]", "Z = a"]
        ]
    );
    assert_prolog_success!(
        &mut wam,
        "p(X, Y), !, q(Y, X).",
        [
            ["X = a", "Y = [f(g(x))]"],
            ["X = a", "Y = [f(g(y))]"],
            ["X = a", "Y = [f(g(z))]"]
        ]
    );

    submit(
        &mut wam,
        "p(X, [f(g(x))]). p(X, [f(g(y))]). p(X, [f(g(z))]).",
    );

    assert_prolog_failure!(&mut wam, "q(f(X), Y), p(X, Y).");
    assert_prolog_success!(
        &mut wam,
        "q(X, Y), p(X, Y).",
        [
            ["Y = [f(g(x))]", "X = [f(g(x))]"],
            ["Y = [f(g(y))]", "X = [f(g(x))]"],
            ["Y = [f(g(z))]", "X = [f(g(x))]"],
            ["Y = [f(g(x))]", "X = [f(g(y))]"],
            ["Y = [f(g(y))]", "X = [f(g(y))]"],
            ["Y = [f(g(z))]", "X = [f(g(y))]"]
        ]
    );
    assert_prolog_success!(
        &mut wam,
        "p(X, Y), q(X, Y).",
        [
            ["Y = [f(g(x))]", "X = [f(g(x))]"],
            ["Y = [f(g(x))]", "X = [f(g(y))]"],
            ["Y = [f(g(y))]", "X = [f(g(x))]"],
            ["Y = [f(g(y))]", "X = [f(g(y))]"],
            ["Y = [f(g(z))]", "X = [f(g(x))]"],
            ["Y = [f(g(z))]", "X = [f(g(y))]"]
        ]
    );
    assert_prolog_success!(
        &mut wam,
        "p(X, Y), q(Y, X).",
        [
            ["Y = [f(g(x))]", "X = _10"],
            ["Y = [f(g(y))]", "X = _10"],
            ["Y = [f(g(z))]", "X = a"]
        ]
    );
    assert_prolog_success!(
        &mut wam,
        "q(X, Y), p(Y, X).",
        [
            ["Y = _9", "X = [f(g(x))]"],
            ["Y = _9", "X = [f(g(y))]"],
            ["Y = a", "X = [f(g(z))]"]
        ]
    );
}

#[test]
fn test_queries_on_call_n() {
    let mut wam = Machine::new(readline::input_stream());

    submit(
        &mut wam,
        "maplist(_, []).
                      maplist(P, [X|Xs]) :- call(P, X), maplist(P, Xs).",
    );
    submit(&mut wam, "f(a). f(b). f(c).");

    assert_prolog_success!(
        &mut wam,
        "maplist(f, [X,Y,Z]).",
        [
            ["X = a", "Y = a", "Z = a"],
            ["X = a", "Y = a", "Z = b"],
            ["X = a", "Y = a", "Z = c"],
            ["X = a", "Y = b", "Z = a"],
            ["X = a", "Y = b", "Z = b"],
            ["X = a", "Y = b", "Z = c"],
            ["X = a", "Y = c", "Z = a"],
            ["X = a", "Y = c", "Z = b"],
            ["X = a", "Y = c", "Z = c"],
            ["X = b", "Y = a", "Z = a"],
            ["X = b", "Y = a", "Z = b"],
            ["X = b", "Y = a", "Z = c"],
            ["X = b", "Y = b", "Z = a"],
            ["X = b", "Y = b", "Z = b"],
            ["X = b", "Y = b", "Z = c"],
            ["X = b", "Y = c", "Z = a"],
            ["X = b", "Y = c", "Z = b"],
            ["X = b", "Y = c", "Z = c"],
            ["X = c", "Y = a", "Z = a"],
            ["X = c", "Y = a", "Z = b"],
            ["X = c", "Y = a", "Z = c"],
            ["X = c", "Y = b", "Z = a"],
            ["X = c", "Y = b", "Z = b"],
            ["X = c", "Y = b", "Z = c"],
            ["X = c", "Y = c", "Z = a"],
            ["X = c", "Y = c", "Z = b"],
            ["X = c", "Y = c", "Z = c"]
        ]
    );

    assert_prolog_success!(
        &mut wam,
        "maplist(f, [a,Y,Z]).",
        [
            ["Y = a", "Z = a"],
            ["Y = a", "Z = b"],
            ["Y = a", "Z = c"],
            ["Y = b", "Z = a"],
            ["Y = b", "Z = b"],
            ["Y = b", "Z = c"],
            ["Y = c", "Z = a"],
            ["Y = c", "Z = b"],
            ["Y = c", "Z = c"]
        ]
    );

    assert_prolog_success!(
        &mut wam,
        "maplist(f, [X,a,b]).",
        [["X = a"], ["X = b"], ["X = c"]]
    );
    assert_prolog_success!(&mut wam, "maplist(f, [c,a,b]).");
    assert_prolog_failure!(&mut wam, "maplist(f, [d,e,f]).");
    assert_prolog_success!(&mut wam, "maplist(f, []).");
    assert_prolog_failure!(&mut wam, "maplist(f(X), [a,b,c]).");

    submit(&mut wam, "f(X) :- call(X), call(X).");
    submit(&mut wam, "p(x). p(y).");

    assert_prolog_failure!(&mut wam, "f(p).");
    assert_prolog_success!(&mut wam, "f(p(X)).", [["X = x"], ["X = y"]]);
    assert_prolog_success!(&mut wam, "f(p(x)).");
    assert_prolog_failure!(&mut wam, "f(p(w)).");
    assert_prolog_failure!(&mut wam, "f(p(X, Y)).");

    submit(&mut wam, "f(P) :- call(P, X), call(P, Y).");

    assert_prolog_success!(&mut wam, "f(p).");
    assert_prolog_failure!(&mut wam, "f(non_existent).");

    submit(&mut wam, "f(P, X, Y) :- call(P, X), call(P, Y).");

    assert_prolog_success!(
        &mut wam,
        "f(p, X, Y).",
        [
            ["Y = x", "X = x"],
            ["Y = y", "X = x"],
            ["Y = x", "X = y"],
            ["Y = y", "X = y"]
        ]
    );
    assert_prolog_success!(&mut wam, "f(p, x, Y).", [["Y = x"], ["Y = y"]]);
    assert_prolog_success!(&mut wam, "f(p, X, y).", [["X = x"], ["X = y"]]);
    assert_prolog_success!(&mut wam, "f(p, x, y).");
    assert_prolog_failure!(&mut wam, "f(p, X, z).");
    assert_prolog_failure!(&mut wam, "f(p, z, Y).");

    assert_prolog_success!(&mut wam, "call(p, X).", [["X = x"], ["X = y"]]);
    assert_prolog_success!(&mut wam, "call(p, x).");
    assert_prolog_success!(&mut wam, "call(p, y).");
    assert_prolog_failure!(&mut wam, "call(p, z).");

    submit(&mut wam, "r(f(X)) :- p(X). r(g(Y)) :- p(Y).");

    assert_prolog_success!(
        &mut wam,
        "f(r, X, Y).",
        [
            ["X = f(x)", "Y = f(x)"],
            ["X = f(x)", "Y = f(y)"],
            ["X = f(x)", "Y = g(x)"],
            ["X = f(x)", "Y = g(y)"],
            ["X = f(y)", "Y = f(x)"],
            ["X = f(y)", "Y = f(y)"],
            ["X = f(y)", "Y = g(x)"],
            ["X = f(y)", "Y = g(y)"],
            ["X = g(x)", "Y = f(x)"],
            ["X = g(x)", "Y = f(y)"],
            ["X = g(x)", "Y = g(x)"],
            ["X = g(x)", "Y = g(y)"],
            ["X = g(y)", "Y = f(x)"],
            ["X = g(y)", "Y = f(y)"],
            ["X = g(y)", "Y = g(x)"],
            ["X = g(y)", "Y = g(y)"]
        ]
    );
    assert_prolog_success!(
        &mut wam,
        "f(r, X, X).",
        [["X = f(x)"], ["X = f(y)"], ["X = g(x)"], ["X = g(y)"]]
    );
    assert_prolog_success!(
        &mut wam,
        "f(r, f(X), g(Y)).",
        [
            ["X = x", "Y = x"],
            ["X = x", "Y = y"],
            ["X = y", "Y = x"],
            ["X = y", "Y = y"]
        ]
    );
    assert_prolog_failure!(&mut wam, "f(r, j(X), h(Y)).");

    submit(&mut wam, "p(one, one). p(one, two). p(two, two).");

    assert_prolog_success!(
        &mut wam,
        "f(p(one), X, Y).",
        [
            ["X = one", "Y = one"],
            ["X = one", "Y = two"],
            ["X = two", "Y = one"],
            ["X = two", "Y = two"]
        ]
    );
    assert_prolog_success!(&mut wam, "f(p(one), X, X).", [["X = one"], ["X = two"]]);
    assert_prolog_success!(&mut wam, "f(p(one), one, Y).", [["Y = one"], ["Y = two"]]);
    assert_prolog_success!(&mut wam, "f(p(one), one, two).");
    assert_prolog_failure!(&mut wam, "f(p(one), one, three).");

    assert_prolog_failure!(&mut wam, "f(p(two), one, two).");
    assert_prolog_failure!(&mut wam, "f(p(two), two, one).");
    assert_prolog_success!(&mut wam, "f(p(two), two, two).");
    assert_prolog_failure!(&mut wam, "f(p(two), two, three).");

    assert_prolog_failure!(&mut wam, "f(p(three), X, Y).");
    assert_prolog_failure!(&mut wam, "f(p(three), X, X).");
    assert_prolog_failure!(&mut wam, "f(p(three), one, Y).");
    assert_prolog_failure!(&mut wam, "f(p(three), one, two).");
    assert_prolog_failure!(&mut wam, "f(p(three), one, three).");

    submit(&mut wam, "f(P, X) :- call(P, X).");

    assert_prolog_success!(&mut wam, "f(p(one), one).");
    assert_prolog_success!(&mut wam, "f(p(two), two).");
    assert_prolog_failure!(&mut wam, "f(p(two), one).");
    assert_prolog_failure!(&mut wam, "f(p(three), one).");
    assert_prolog_failure!(&mut wam, "f(p(one), three).");
    assert_prolog_failure!(&mut wam, "f(p(two), three).");

    submit(&mut wam, "p(f(g(X)), compound, [lists,are,good]).");

    assert_prolog_success!(
        &mut wam,
        "call(p(f(g(X))),Y,Z).",
        [["Y = compound", "Z = [lists,are,good]", "X = _3"]]
    );

    submit(
        &mut wam,
        "david_lynch(coffee).
                      david_lynch(pie).
                      david_lynch(kyle(Film)) :- kyle(Film).",
    );

    submit(
        &mut wam,
        "kyle(dune).
                      kyle(blue_velvet).
                      kyle(showgirls).
                      kyle(flintstones).",
    );

    assert_prolog_success!(
        &mut wam,
        "call(david_lynch,X).",
        [
            ["X = coffee"],
            ["X = pie"],
            ["X = kyle(dune)"],
            ["X = kyle(blue_velvet)"],
            ["X = kyle(showgirls)"],
            ["X = kyle(flintstones)"]
        ]
    );
    assert_prolog_success!(
        &mut wam,
        "call(david_lynch,kyle(Film)).",
        [
            ["Film = dune"],
            ["Film = blue_velvet"],
            ["Film = showgirls"],
            ["Film = flintstones"]
        ]
    );
    assert_prolog_failure!(&mut wam, "call(david_lynch,kyle(Film),_).");

    submit(&mut wam, "call_mult(P,X) :- call(call(P),X).");

    assert_prolog_success!(
        &mut wam,
        "call_mult(p(X),Y).",
        [
            ["Y = one", "X = one"],
            ["Y = two", "X = one"],
            ["Y = two", "X = two"]
        ]
    );
    assert_prolog_success!(&mut wam, "call_mult(p(X),X).", [["X = one"], ["X = two"]]);
    assert_prolog_success!(&mut wam, "call_mult(p(one),X).", [["X = one"], ["X = two"]]);
    assert_prolog_success!(&mut wam, "call_mult(p(X),one).", [["X = one"]]);

    assert_prolog_failure!(&mut wam, "call_mult(p(two),one).");
    assert_prolog_success!(&mut wam, "call_mult(p(two),two).");

    assert_prolog_success!(
        &mut wam,
        "call(call(p(one)),X),call(call(p(two)),two).",
        [["X = one"], ["X = two"]]
    );
    assert_prolog_success!(
        &mut wam,
        "call(call(p(one,X))),call(call(p(two,two))).",
        [["X = one"], ["X = two"]]
    );
    assert_prolog_failure!(&mut wam, "call(call(p(one)),X),call(call(p(two)),one).");
    assert_prolog_success!(
        &mut wam,
        "call(call(p(X)),X),call(call(p(Y)),Y).",
        [
            ["X = one", "Y = one"],
            ["X = one", "Y = two"],
            ["X = two", "Y = one"],
            ["X = two", "Y = two"]
        ]
    );
    assert_prolog_success!(
        &mut wam,
        "call(call(p(X)),Y),call(call(p(Y)),X).",
        [["X = one", "Y = one"], ["X = two", "Y = two"]]
    );
    assert_prolog_success!(
        &mut wam,
        "call(call(p),X,Y),call(call(call(p)),X,Y).",
        [
            ["X = one", "Y = one"],
            ["Y = two", "X = one"],
            ["Y = two", "X = two"]
        ]
    );
    assert_prolog_success!(
        &mut wam,
        "call(call(p),X,Y),call(call(call(p(X))),Y).",
        [
            ["X = one", "Y = one"],
            ["Y = two", "X = one"],
            ["Y = two", "X = two"]
        ]
    );
    assert_prolog_failure!(&mut wam, "call(call(p),X,Y),call(call(call(p(X))),X,Y).");
    assert_prolog_success!(
        &mut wam,
        "call(call(p),X,Y),call(call(call(p(X))),X).",
        [
            ["X = one", "Y = one"],
            ["Y = two", "X = one"],
            ["Y = two", "X = two"]
        ]
    );

    submit(&mut wam, "f(call(f,undefined)). f(undefined).");
    submit(&mut wam, "call_var(P) :- P.");

    assert_prolog_success!(&mut wam, "f(X),call_var(X).", [["X = call(f,undefined)"]]);
    assert_prolog_success!(
        &mut wam,
        "f(call(f,Q)),call_var(call(f,Q)).",
        [["Q = undefined"]]
    );
    assert_prolog_failure!(&mut wam, "call_var(call(undefined,Q)).");

    assert_prolog_failure!(&mut wam, "call(call).");
    assert_prolog_failure!(&mut wam, "call(call(call)).");
    assert_prolog_failure!(&mut wam, "call(call(call(call))).");
    assert_prolog_failure!(&mut wam, "call(call(call(call(call)))).");
    assert_prolog_failure!(&mut wam, "call(call(call(call(call(call))))).");
    assert_prolog_success!(
        &mut wam,
        "call(call(call(call(call(call(p(X))))))).",
        [["X = x"], ["X = y"]]
    );
}

#[test]
fn test_queries_on_arithmetic() {
    let mut wam = Machine::new(readline::input_stream());

    assert_prolog_success!(&mut wam, "X is 1, X is X.", [["X = 1"]]);
    assert_prolog_failure!(&mut wam, "X is 1, X is X + 1.");
    assert_prolog_success!(&mut wam, "X is 1, X is X + 0.", [["X = 1"]]);
    assert_prolog_success!(&mut wam, "X is 1, X is X * 1.", [["X = 1"]]);
    assert_prolog_failure!(&mut wam, "X is 1, X is X * 2.");

    // assert_prolog_failure!(&mut wam, "X is 1 + a.");
    // assert_prolog_failure!(&mut wam, "X is 1 + Y.");
    assert_prolog_success!(
        &mut wam,
        "Y is 2 + 2 - 2, X is 1 + Y, X = 3.",
        [["X = 3", "Y = 2"]]
    );
    assert_prolog_failure!(&mut wam, "Y is 2 + 2 - 2, X is 1 + Y, X = 2.");

    assert_prolog_success!(&mut wam, "6 is 6.");
    assert_prolog_success!(&mut wam, "6 is 3 + 3.");
    assert_prolog_success!(&mut wam, "6 is 3 * 2.");
    assert_prolog_failure!(&mut wam, "7 is 3 * 2.");
    assert_prolog_failure!(&mut wam, "7 is 3.5 * 2.");
    assert_prolog_success!(&mut wam, "7.0 is 3.5 * 2.");
    assert_prolog_success!(&mut wam, "7.0 is 14 / 2.");
    assert_prolog_failure!(&mut wam, "4.666 is 14.0 / 3.");
    assert_prolog_success!(&mut wam, "4.0 is 8.0 / 2.");

    submit(&mut wam, "f(X) :- X is 5 // 0.");

    assert_prolog_success!(
        &mut wam,
        "catch(f(X), error(evaluation_error(E), _), true), E = zero_divisor.",
        [["E = zero_divisor", "X = _1"]]
    );

    submit(&mut wam, "f(X) :- X is (5 rdiv 1) / 0.");

    assert_prolog_success!(
        &mut wam,
        "catch(f(X), error(evaluation_error(E), _), true), E = zero_divisor.",
        [["E = zero_divisor", "X = _1"]]
    );

    submit(&mut wam, "f(X) :- X is 5.0 / 0.");

    assert_prolog_success!(
        &mut wam,
        "catch(f(X), error(evaluation_error(E), _), true), E = zero_divisor.",
        [["E = zero_divisor", "X = _1"]]
    );

    assert_prolog_success!(
        &mut wam,
        "X is ((3 + 4) // 2) + 2 - 1 // 1, Y is 2+2, Z is X+Y.",
        [["Y = 4", "X = 4", "Z = 8"]]
    );

    assert_prolog_success!(
        &mut wam,
        "X is ((3 + 4) // 2) + 2 - 1 // 1, Y is 2+2, Z = 8, Y is 4.",
        [["Y = 4", "X = 4", "Z = 8"]]
    );

    assert_prolog_success!(
        &mut wam,
        "X is (3 rdiv 4) / 2, Y is 3 rdiv 8.",
        [["X = 0.375", "Y = 3/8"]]
    );

    assert_prolog_success!(&mut wam, "X is 10 xor -4, X is -10.", [["X = -10"]]);
    assert_prolog_success!(&mut wam, "X is 4 xor -7, X is -3.", [["X = -3"]]);
    assert_prolog_success!(&mut wam, "X is 10 xor 5 + 55, X = 70.", [["X = 70"]]);

    assert_prolog_success!(&mut wam, "X is 10 rem -3, X = 1.", [["X = 1"]]);
    assert_prolog_success!(&mut wam, "X is 10 mod -3, X is -2.", [["X = -2"]]);

    assert_prolog_success!(&mut wam, "call(is, X, 3 + 4).", [["X = 7"]]);

    assert_prolog_success!(
        &mut wam,
        "Y is 3 + 3, call(is, X, Y + 4).",
        [["Y = 6", "X = 10"]]
    );
    assert_prolog_success!(&mut wam, "call(is, X, 3 + 4.5).", [["X = 7.5"]]);
    assert_prolog_success!(
        &mut wam,
        "X is 2 rdiv 3, call(is, Y, X*X).",
        [["X = 2/3", "Y = 4/9"]]
    );

    assert_prolog_failure!(&mut wam, "call(>, 3, 3 + 3).");
    assert_prolog_failure!(&mut wam, "X is 3 + 3, call(>, 3, X).");

    assert_prolog_success!(&mut wam, "X is 3 + 3, call(<, 3, X).", [["X = 6"]]);
    assert_prolog_success!(&mut wam, "X is 3 + 3, X =:= 3 + 3.", [["X = 6"]]);

    assert_prolog_success!(
        &mut wam,
        "catch(call(is, X, 3 // 0), error(E, _), true).",
        [["X = _5", "E = evaluation_error(zero_divisor)"]]
    );

    assert_prolog_success!(
        &mut wam,
        "catch(call(is, X, 3 // 3), _, true).",
        [["X = 1"]]
    );

    submit(
        &mut wam,
        "f(X, Sum) :- ( integer(X) -> Sum is X + X * X + 3 ;
                                     var(X) -> Sum = 1, X = 1 ).",
    );

    assert_prolog_success!(&mut wam, "f(X, Sum).", [["X = 1", "Sum = 1"]]);
    assert_prolog_success!(&mut wam, "f(5, Sum).", [["Sum = 33"]]);
    assert_prolog_success!(&mut wam, "f(5, 33).");
    assert_prolog_failure!(&mut wam, "f(5, 32).");

    // exponentiation.

    // the ~ operators tests whether |X - Y| <= 1/10000...
    // or whatever degree of approximation used by Newton's method in rational_pow.
    submit(&mut wam, ":- op(900, xfx, ~).");
    submit(&mut wam, "X ~ Y :- abs(X - Y) =< 1 rdiv 10000.");

    assert_prolog_success!(&mut wam, "X is 3 ** 3.", [["X = 27"]]);
    assert_prolog_success!(&mut wam, "X is 3 ** 0.", [["X = 1"]]);
    assert_prolog_success!(&mut wam, "X is 3 ** -0.", [["X = 1"]]);
    assert_prolog_success!(&mut wam, "X is 3 ** 1.", [["X = 3"]]);
    assert_prolog_success!(&mut wam, "X is (-3) ** 3.", [["X = -27"]]);
    assert_prolog_success!(&mut wam, "X is (-3) ** 3.", [["X = -27"]]);
    assert_prolog_success!(&mut wam, "X is (-3) ** 0.", [["X = 1"]]);
    assert_prolog_success!(&mut wam, "X is (-3) ** -0.", [["X = 1"]]);
    assert_prolog_success!(&mut wam, "X is (-3) ** 1.", [["X = -3"]]);
    //    assert_prolog_success!(&mut wam, "X is (1 rdiv 27) ** -3, X ~ 19683.");
    //    assert_prolog_success!(&mut wam, "X is (-1 rdiv 27) ** -3, X ~ -19683.");

    assert_prolog_success!(&mut wam, "X is 0.0 ** 0.", [["X = 1.0"]]);
    assert_prolog_success!(
        &mut wam,
        "catch(_ is 0.0 ** -2342, error(E, _), true).",
        [["E = evaluation_error(undefined)"]]
    );
    assert_prolog_success!(&mut wam, "X is 0.0 ** 2342.", [["X = 0"]]);

    assert_prolog_success!(
        &mut wam,
        "catch(_ is (-3) ** (1 rdiv 2), error(E, _), true).",
        [["E = evaluation_error(undefined)"]]
    );
    assert_prolog_success!(
        &mut wam,
        "catch(_ is (-3/2) ** (1 rdiv 2), error(E, _), true).",
        [["E = evaluation_error(undefined)"]]
    );
    assert_prolog_success!(
        &mut wam,
        "catch(_ is (-3 rdiv 2) ** (1 rdiv 4), error(E, _), true).",
        [["E = evaluation_error(undefined)"]]
    );
    assert_prolog_success!(
        &mut wam,
        "catch(_ is (-3 rdiv 2) ** (-1 rdiv 4), error(E, _), true).",
        [["E = evaluation_error(undefined)"]]
    );
    assert_prolog_success!(
        &mut wam,
        "catch(_ is 0 ** (-5 rdiv 4), error(E, _), true).",
        [["E = evaluation_error(undefined)"]]
    );

    assert_prolog_success!(&mut wam, "X is 3 ** (1 rdiv 3), Y is X ** 3, Y ~ 3.");
    //    assert_prolog_success!(&mut wam, "X is (-3) ** (1 rdiv 3), Y is X ** 3, Y ~ -3.");
    //    assert_prolog_failure!(&mut wam, "X is (-5) ** (1 rdiv 3), Y is X ** 3, Y ~ -3.");
    assert_prolog_success!(&mut wam, "X is 5 ** (1 rdiv 3), Y is X ** 3, Y ~ 5.");
    assert_prolog_success!(
        &mut wam,
        "X is (1 rdiv 3) ** 0.5, Y is X ** 2, 1 rdiv 3 ~ Y."
    );

    //    assert_prolog_success!(&mut wam, "X is (-5) ** (-1 rdiv 3), Y is X ** 3, Y ~ -1 rdiv 5.");
    //    assert_prolog_failure!(&mut wam, "X is (-5) ** (-1 rdiv 3), Y is X ** 3, Y ~ 1 rdiv 5.");

    assert_prolog_success!(&mut wam, "X is (0 rdiv 5) ** 5.", [["X = 0"]]);
    assert_prolog_success!(&mut wam, "X is (-0 rdiv 5) ** 5.", [["X = 0"]]);
    assert_prolog_success!(&mut wam, "X is (0 rdiv 5) ** 0.", [["X = 1.0"]]);
    assert_prolog_success!(
        &mut wam,
        "catch(_ is (0 rdiv 0) ** 5, error(E, _), true).",
        [["E = evaluation_error(zero_divisor)"]]
    );
}

#[test]
fn test_queries_on_exceptions() {
    let mut wam = Machine::new(readline::input_stream());

    submit(&mut wam, "f(a). f(_) :- throw(stuff).");
    submit(&mut wam, "handle(stuff).");

    assert_prolog_success!(
        &mut wam,
        "catch(f(X), E, handle(E)).",
        [["E = _2", "X = a"], ["E = stuff", "X = _1"]]
    );

    submit(&mut wam, "f(a). f(X) :- g(X).");
    submit(&mut wam, "g(x). g(y). g(z).");
    submit(&mut wam, "handle(x). handle(y).");

    assert_prolog_success!(
        &mut wam,
        "catch(f(X), X, handle(X)).",
        [["X = a"], ["X = x"], ["X = y"], ["X = z"]]
    );
    assert_prolog_success!(&mut wam, "catch(f(a), _, handle(X)).", [["X = _4"]]);
    assert_prolog_failure!(&mut wam, "catch(f(b), _, handle(X)).");

    submit(&mut wam, "g(x). g(X) :- throw(x).");

    assert_prolog_success!(
        &mut wam,
        "catch(f(X), x, handle(X)).",
        [["X = a"], ["X = x"], ["X = x"], ["X = y"]]
    );
    assert_prolog_success!(
        &mut wam,
        "catch(f(X), x, handle(z)).",
        [["X = a"], ["X = x"]]
    );
    assert_prolog_success!(&mut wam, "catch(f(z), x, handle(x)).");
    assert_prolog_success!(&mut wam, "catch(f(z), x, handle(y)).");
    assert_prolog_failure!(&mut wam, "catch(f(z), x, handle(z)).");

    submit(&mut wam, "f(X) :- throw(stuff).");
    submit(&mut wam, "handle(stuff). handle(other_stuff).");

    // the first 3 cases should deterministically succeed.
    assert_prolog_success!(
        &mut wam,
        "catch(f(X), E, handle(E)).",
        [["X = _1", "E = stuff"]]
    );
    assert_prolog_success!(
        &mut wam,
        "catch(f(X), E, handle(stuff)).",
        [["X = _1", "E = stuff"]]
    );
    assert_prolog_success!(
        &mut wam,
        "catch(f(X), E, handle(other_stuff)).",
        [["X = _1", "E = stuff"]]
    );
    assert_prolog_failure!(&mut wam, "catch(f(X), E, handle(not_stuff)).");

    submit(&mut wam, "f(success). f(X) :- catch(g(X), E, handle(E)).");
    submit(&mut wam, "g(g_success). g(g_success_2). g(X) :- throw(X).");
    submit(&mut wam, "handle(x). handle(y). handle(z).");

    assert_prolog_success!(
        &mut wam,
        "catch(f(X), E, E).",
        [
            ["X = success", "E = _2"],
            ["X = g_success", "E = _2"],
            ["X = g_success_2", "E = _2"],
            ["X = _1", "E = _2"],
            ["X = _1", "E = _2"],
            ["X = _1", "E = _2"]
        ]
    );
    assert_prolog_failure!(&mut wam, "catch(f(fail), _, _).");
    assert_prolog_success!(&mut wam, "catch(f(x), _, _).");
    assert_prolog_success!(&mut wam, "catch(f(y), _, _).");
    assert_prolog_success!(&mut wam, "catch(f(z), _, _).");

    submit(&mut wam, "f(success). f(E) :- catch(g(E), E, handle(E)).");
    submit(&mut wam, "g(g_success). g(g_success_2). g(X) :- throw(X).");
    submit(
        &mut wam,
        "handle(x). handle(y). handle(z). handle(v) :- throw(X).",
    );

    assert_prolog_success!(
        &mut wam,
        "catch(f(X), E, E).",
        [
            ["X = success", "E = _2"],
            ["X = g_success", "E = _2"],
            ["X = g_success_2", "E = _2"],
            ["X = x", "E = _2"],
            ["X = y", "E = _2"],
            ["X = z", "E = _2"]
        ]
    );

    submit(
        &mut wam,
        "handle(x). handle(y). handle(z). handle(v) :- throw(handle_top(X)).",
    );
    submit(&mut wam, "handle_top(an_error_1). handle_top(an_error_2).");

    assert_prolog_success!(
        &mut wam,
        "catch(f(X), E, E).",
        [
            ["X = success", "E = _2"],
            ["X = g_success", "E = _2"],
            ["X = g_success_2", "E = _2"],
            ["X = x", "E = _2"],
            ["X = y", "E = _2"],
            ["X = z", "E = _2"],
            ["X = _1", "E = handle_top(an_error_1)"],
            ["X = _1", "E = handle_top(an_error_2)"]
        ]
    );

    submit(
        &mut wam,
        "handle(x). handle(y). handle(z). handle(v) :- throw(X).",
    );

    assert_prolog_success!(
        &mut wam,
        "catch(f(X), E, handle_top(E)).",
        [
            ["X = success", "E = _2"],
            ["X = g_success", "E = _2"],
            ["X = g_success_2", "E = _2"],
            ["X = x", "E = _2"],
            ["X = y", "E = _2"],
            ["X = z", "E = _2"],
            ["E = an_error_1", "X = _1"],
            ["E = an_error_2", "X = _1"]
        ]
    );
}

#[test]
fn test_queries_on_skip_max_list() {
    let mut wam = Machine::new(readline::input_stream());

    // test on proper and empty lists.
    assert_prolog_success!(
        &mut wam,
        "'$skip_max_list'(N,5,[],Xs).",
        [["Xs = []", "N = 0"]]
    );
    assert_prolog_success!(
        &mut wam,
        "'$skip_max_list'(N,5,[a,b,c],Xs).",
        [["Xs = []", "N = 3"]]
    );
    assert_prolog_success!(
        &mut wam,
        "'$skip_max_list'(N,2,[a,b,c],Xs).",
        [["Xs = [c]", "N = 2"]]
    );
    assert_prolog_success!(
        &mut wam,
        "'$skip_max_list'(N,3,[a,b,c],Xs).",
        [["Xs = []", "N = 3"]]
    );

    assert_prolog_success!(
        &mut wam,
        "'$skip_max_list'(N,0,[],Xs).",
        [["Xs = []", "N = 0"]]
    );
    assert_prolog_success!(
        &mut wam,
        "'$skip_max_list'(N,0,[a,b,c],Xs).",
        [["Xs = [a,b,c]", "N = 0"]]
    );
    assert_prolog_success!(
        &mut wam,
        "'$skip_max_list'(N,0,[a,b,c],Xs).",
        [["Xs = [a,b,c]", "N = 0"]]
    );
    assert_prolog_success!(
        &mut wam,
        "'$skip_max_list'(N,0,[a,b,c],Xs).",
        [["Xs = [a,b,c]", "N = 0"]]
    );

    assert_prolog_failure!(&mut wam, "'$skip_max_list'(4,0,[],Xs).");
    assert_prolog_failure!(&mut wam, "'$skip_max_list'(3,0,[a,b,c],Xs).");
    assert_prolog_failure!(&mut wam, "'$skip_max_list'(2,0,[a,b,c],Xs).");
    assert_prolog_failure!(&mut wam, "'$skip_max_list'(1,0,[a,b,c],Xs).");

    assert_prolog_success!(&mut wam, "'$skip_max_list'(0,5,[],Xs).", [["Xs = []"]]);
    assert_prolog_success!(&mut wam, "'$skip_max_list'(3,5,[a,b,c],Xs).", [["Xs = []"]]);
    assert_prolog_success!(
        &mut wam,
        "'$skip_max_list'(2,2,[a,b,c],Xs).",
        [["Xs = [c]"]]
    );
    assert_prolog_success!(&mut wam, "'$skip_max_list'(3,3,[a,b,c],Xs).", [["Xs = []"]]);

    // tests on proper and empty lists with no max.

    // test on proper and empty lists.
    assert_prolog_success!(
        &mut wam,
        "'$skip_max_list'(N,-1,[],Xs).",
        [["Xs = []", "N = 0"]]
    );
    assert_prolog_success!(
        &mut wam,
        "'$skip_max_list'(N,-1,[a,b,c],Xs).",
        [["Xs = []", "N = 3"]]
    );

    assert_prolog_success!(
        &mut wam,
        "'$skip_max_list'(N,-1,[],Xs).",
        [["Xs = []", "N = 0"]]
    );

    assert_prolog_failure!(&mut wam, "'$skip_max_list'(4,-1,[],Xs).");
    assert_prolog_success!(
        &mut wam,
        "'$skip_max_list'(3,-1,[a,b,c],Xs).",
        [["Xs = []"]]
    );

    assert_prolog_success!(&mut wam, "'$skip_max_list'(0,-1,[],Xs).", [["Xs = []"]]);
    assert_prolog_success!(
        &mut wam,
        "'$skip_max_list'(3,-1,[a,b,c],Xs).",
        [["Xs = []"]]
    );

    // tests on partial lists.
    assert_prolog_success!(
        &mut wam,
        "'$skip_max_list'(3,4,[a,b,c|X],Xs0).",
        [["X = _1", "Xs0 = _1"]]
    );
    assert_prolog_success!(
        &mut wam,
        "'$skip_max_list'(3,3,[a,b,c|X],Xs0).",
        [["X = _1", "Xs0 = _1"]]
    );
    assert_prolog_failure!(&mut wam, "'$skip_max_list'(3,2,[a,b,c|X],Xs0).");
    assert_prolog_failure!(&mut wam, "'$skip_max_list'(3,1,[a,b,c|X],Xs0).");
    assert_prolog_failure!(&mut wam, "'$skip_max_list'(3,0,[a,b,c|X],Xs0).");

    // tests on cyclic lists.
    assert_prolog_failure!(&mut wam, "Xs = [a,b|Xs],'$skip_max_list'(3,5,X,Xs0).");
    assert_prolog_failure!(
        &mut wam,
        "X = [a,b|Y],Y = [c,d|X],'$skip_max_list'(4,5,X,Xs0)."
    );
    assert_prolog_failure!(
        &mut wam,
        "X = [a,b|Y],Y = [c,d|X],'$skip_max_list'(4,3,X,Xs0)."
    );

    // tests on non lists.
    assert_prolog_success!(
        &mut wam,
        "'$skip_max_list'(N,9,non_list,Xs).",
        [["Xs = non_list", "N = 0"]]
    );
}

#[test]
fn test_queries_on_conditionals() {
    let mut wam = Machine::new(readline::input_stream());

    submit(
        &mut wam,
        "test(A) :- (   A =:= 2 -> writeq(\"A is 2\")
                                 ;   A =:= 3 -> writeq(\"A is 3\")
                                 ;   A = \"not 2 or 3\"
                                 ).",
    );

    assert_prolog_success!(
        &mut wam,
        "catch(test(A), error(instantiation_error, _), true)."
    );
    assert_prolog_success!(&mut wam, "A = 2, test(A).", [["A = 2"]]);
    assert_prolog_success!(
        &mut wam,
        "A = 3, test(A), B = 3, test(B).",
        [["A = 3", "B = 3"]]
    );

    submit(&mut wam, "f(a). f(b).");
    submit(&mut wam, "g(1). g(2). g(3).");

    submit(
        &mut wam,
        "typed_dispatch(X) :- ( var(X) -> f(X)
                                           ; integer(X) -> g(X)
                                           ; atomic(X)).",
    );

    assert_prolog_success!(&mut wam, "typed_dispatch(X).", [["X = a"], ["X = b"]]);
    assert_prolog_success!(&mut wam, "typed_dispatch(a).");
    assert_prolog_success!(&mut wam, "typed_dispatch(b).");
    assert_prolog_success!(&mut wam, "typed_dispatch(c).");
    assert_prolog_success!(&mut wam, "typed_dispatch(1).");
    assert_prolog_success!(&mut wam, "typed_dispatch(2).");
    assert_prolog_success!(&mut wam, "typed_dispatch(3).");
    assert_prolog_failure!(&mut wam, "typed_dispatch(4).");
    assert_prolog_failure!(&mut wam, "typed_dispatch(5).");
    assert_prolog_failure!(&mut wam, "typed_dispatch(compound(term)).");

    submit(&mut wam, "f(a). f(b). f(compound(term)).");
    submit(
        &mut wam,
        "g(X, Y) :- f(X), (atomic(X) -> X = a ; X = a ; X = compound(Y)).",
    );

    assert_prolog_success!(
        &mut wam,
        "g(X, Y).",
        [["Y = _1", "X = a"], ["Y = term", "X = compound(term)"]]
    );

    assert_prolog_success!(&mut wam, "g(X, X).", [["X = a"]]);
    assert_prolog_success!(&mut wam, "g(compound(X), X).", [["X = term"]]);
    assert_prolog_success!(&mut wam, "g(X, term).", [["X = a"], ["X = compound(term)"]]);
    assert_prolog_success!(&mut wam, "g(a, _).");
    assert_prolog_success!(&mut wam, "g(X, _), X = a.", [["X = a"]]);

    submit(
        &mut wam,
        "g(X) :- var(X) -> (var(X) -> X is 3 + 3 ; X = not_6).",
    );

    assert_prolog_success!(&mut wam, "g(X).", [["X = 6"]]);
    assert_prolog_failure!(&mut wam, "g(1).");
    assert_prolog_failure!(&mut wam, "g(6).");
    assert_prolog_failure!(&mut wam, "g(not_6).");

    assert_prolog_success!(&mut wam, "f(X), (g(Y), !).", [["X = a", "Y = 6"]]);

    submit(
        &mut wam,
        "test(X, [X]) :- (atomic(X) -> true ; throw(type_error(atomic_expected, X))).
                      test(_, _).",
    );

    assert_prolog_success!(
        &mut wam,
        "catch(test(a, [a]), type_error(E), true).",
        [["E = _6"], ["E = _6"]]
    );

    assert_prolog_success!(
        &mut wam,
        "f(X), call(->, atomic(X), true).",
        [["X = a"], ["X = b"]]
    );
}

#[test]
fn test_queries_on_modules() {
    let mut wam = Machine::new(readline::input_stream());

    submit(&mut wam, ":- use_module(library(lists)).");

    submit_code(
        &mut wam,
        "
:- module(my_lists, [local_member/2, reverse/2]).
:- use_module(library(lists), [member/2]).

local_member(X, Xs) :- member(X, Xs).

reverse(Xs, Ys) :- lists:reverse(Xs, Ys).",
    );

    assert_prolog_success!(&mut wam, "my_lists:local_member(1, [1,2,3]).");
    assert_prolog_success!(&mut wam, "my_lists:reverse([a,b,c], [c,b,a]).");

    submit_code(
        &mut wam,
        "
:- module(my_lists_2, [local_member/2]).
:- use_module(library(my_lists), [local_member/2]).",
    );

    assert_prolog_success!(&mut wam, "my_lists_2:local_member(1, [1,2,3]).");
    assert_prolog_success!(
        &mut wam,
        "catch(local_member(X, Xs), error(E, _), true).",
        [[
            "X = _1",
            "E = existence_error(procedure,local_member/2)",
            "Xs = _2"
        ]]
    );

    submit(
        &mut wam,
        ":- use_module(library(lists), [reverse/2]).",
    );

    assert_prolog_success!(
        &mut wam,
        "catch(member(_, _), error(existence_error(procedure, P), _), true).",
        [["P = member/2"]]
    );
    assert_prolog_success!(&mut wam, "reverse(_, _).");

    submit(&mut wam, ":- use_module(library(lists), []).");

    assert_prolog_success!(
        &mut wam,
        "catch(reverse(_, _), error(existence_error(procedure, P), _), true).",
        [["P = reverse/2"]]
    );
}

#[test]
fn test_queries_on_builtins() {
    let mut wam = Machine::new(readline::input_stream());

    submit(&mut wam, ":- use_module(library(lists)).");

    assert_prolog_failure!(&mut wam, "atom(X).");
    assert_prolog_success!(&mut wam, "atom(a).");
    assert_prolog_failure!(&mut wam, "atom(\"string\").");
    assert_prolog_success!(&mut wam, "atom([]).");
    assert_prolog_failure!(&mut wam, "atom(1).");
    assert_prolog_failure!(&mut wam, "atom(0).");
    assert_prolog_failure!(&mut wam, "atom(0.0).");
    assert_prolog_failure!(&mut wam, "atom([a,b,c]).");
    assert_prolog_failure!(&mut wam, "atom(atop(the_trees)).");

    assert_prolog_failure!(&mut wam, "atomic(X).");
    assert_prolog_success!(&mut wam, "atomic(a).");
    assert_prolog_success!(&mut wam, "atomic(\"string\").");
    assert_prolog_success!(&mut wam, "atomic([]).");
    assert_prolog_success!(&mut wam, "atomic(1).");
    assert_prolog_success!(&mut wam, "atomic(0).");
    assert_prolog_success!(&mut wam, "atomic(0.0).");
    assert_prolog_failure!(&mut wam, "atomic([a,b,c]).");
    assert_prolog_failure!(&mut wam, "atomic(atop(the_trees)).");

    assert_prolog_success!(&mut wam, "var(X), X = 3, atomic(X).", [["X = 3"]]);
    assert_prolog_failure!(&mut wam, "var(X), X = 3, var(X).");

    assert_prolog_success!(&mut wam, "arg(1, f(a,b,c,d), Arg).", [["Arg = a"]]);
    assert_prolog_success!(&mut wam, "arg(2, f(a,b,c,d), Arg).", [["Arg = b"]]);
    assert_prolog_success!(&mut wam, "arg(3, f(a,b,c,d), Arg).", [["Arg = c"]]);
    assert_prolog_success!(&mut wam, "arg(4, f(a,b,c,d), Arg).", [["Arg = d"]]);

    assert_prolog_success!(
        &mut wam,
        "catch(arg(N, f, Arg), error(E, _), true).",
        [["E = instantiation_error", "Arg = _3", "N = _1"]]
    );

    assert_prolog_failure!(&mut wam, "arg(N, f(arg, arg, arg), not_arg).");
    assert_prolog_failure!(&mut wam, "arg(1, f(arg, not_arg, not_arg), not_arg).");
    assert_prolog_success!(&mut wam, "arg(2, f(arg, not_arg, not_arg), not_arg).");
    assert_prolog_success!(&mut wam, "arg(3, f(arg, not_arg, not_arg), not_arg).");

    assert_prolog_success!(
        &mut wam,
        "functor(f(a,b,c), F, Arity).",
        [["F = f", "Arity = 3"]]
    );

    assert_prolog_success!(&mut wam, "functor(f(a,b,c), F, N).", [["F = f", "N = 3"]]);
    assert_prolog_failure!(&mut wam, "functor(f(a,b,c), g, N).");
    assert_prolog_success!(&mut wam, "functor(f(a,b,c), F, 3).", [["F = f"]]);
    assert_prolog_failure!(&mut wam, "functor(f(a,b,c), F, 4).");
    assert_prolog_failure!(&mut wam, "functor(f(a,b,c), g, 3).");

    assert_prolog_success!(&mut wam, "functor(F, f, 0).", [["F = f"]]);

    assert_prolog_success!(&mut wam, "functor(Func,f,3).", [["Func = f(_2,_3,_4)"]]);
    assert_prolog_success!(&mut wam, "functor(Func,f,4).", [["Func = f(_2,_3,_4,_5)"]]);

    assert_prolog_success!(
        &mut wam,
        "catch(functor(F,\"sdf\",3),error(E,_),true).",
        [["E = type_error(atom,[s,d,f])", "F = _1"]]
    );
    assert_prolog_success!(
        &mut wam,
        "catch(functor(Func,F,3),error(E,_),true).",
        [["E = instantiation_error", "Func = _1", "F = _2"]]
    );
    assert_prolog_success!(
        &mut wam,
        "catch(functor(Func,f,N),error(E,_),true).",
        [["E = instantiation_error", "Func = _1", "N = _3"]]
    );
    assert_prolog_failure!(&mut wam, "catch(functor(Func,f,N),error(E,_),false).");

    assert_prolog_success!(&mut wam, "X is 3,call(integer,X).");
    assert_prolog_failure!(&mut wam, "X is 3 + 3.5,call(integer,X).");
    assert_prolog_success!(&mut wam, "X is 3 + 3.5,\\+ call(integer,X).");
    assert_prolog_success!(&mut wam, "X is 3 + 3.5,\\+ integer(X).");

    assert_prolog_success!(&mut wam, "Func =.. [atom].", [["Func = atom"]]);
    assert_prolog_success!(&mut wam, "Func =.. [\"sdf\"].", [["Func = [s,d,f]"]]);
    assert_prolog_success!(&mut wam, "Func =.. [1].", [["Func = 1"]]);
    assert_prolog_success!(
        &mut wam,
        "catch(Func =.. [1,2],error(type_error(atom,1),_),true)."
    );
    assert_prolog_success!(&mut wam, "f(1,2,3) =.. List.", [["List = [f,1,2,3]"]]);
    assert_prolog_success!(&mut wam, "f(1,2,3) =.. [f,1,2,3].");
    assert_prolog_failure!(&mut wam, "f(1,2,3) =.. [f,1].");
    assert_prolog_failure!(&mut wam, "f(1,2,3) =.. [g,1,2,3].");
    assert_prolog_success!(
        &mut wam,
        "f(1,2,3) =.. [f,X,Y,Z].",
        [["X = 1", "Y = 2", "Z = 3"]]
    );

    assert_prolog_success!(&mut wam, "length([a,b,c],N).", [["N = 3"]]);
    assert_prolog_success_with_limit!(
        &mut wam,
        "length(Xs,N).",
        [
            ["N = 0", "Xs = []"],
            ["N = 1", "Xs = [_4]"],
            ["N = 2", "Xs = [_4,_8]"],
            ["N = 3", "Xs = [_4,_8,_12]"],
            ["N = 4", "Xs = [_4,_8,_12,_16]"],
            ["N = 5", "Xs = [_4,_8,_12,_16,_20]"]
        ],
        6
    );

    assert_prolog_success!(&mut wam, "length(Xs,3).", [["Xs = [_5,_9,_13]"]]);
    assert_prolog_success!(&mut wam, "length([],N).", [["N = 0"]]);
    assert_prolog_success!(&mut wam, "length(Xs,0).", [["Xs = []"]]);
    assert_prolog_success!(&mut wam, "length([a,b,[a,b,c]],3).");
    assert_prolog_failure!(&mut wam, "length([a,b,[a,b,c]],2).");
    assert_prolog_success!(
        &mut wam,
        "catch(length(a,[]),error(E,_),true).",
        [["E = type_error(integer,[])"]]
    );

    assert_prolog_success!(
        &mut wam,
        "copy_term([1,2,3],[X,Y,Z]).",
        [["Z = 3", "Y = 2", "X = 1"]]
    );
    assert_prolog_success!(
        &mut wam,
        "copy_term(f(X,[a],Z),f(X,Y,Z)).",
        [["X = _3", "Y = [a]", "Z = _5"]]
    );
    assert_prolog_failure!(&mut wam, "copy_term(g(X),f(X)).");
    assert_prolog_success!(&mut wam, "copy_term(f(X),f(X)).", [["X = _1"]]);
    assert_prolog_success!(
        &mut wam,
        "copy_term([[[[X,Y],Y],X]],Term).",
        [["Term = [[[[_22,_26],_26],_22]]", "X = _2", "Y = _0"]]
    );
    assert_prolog_success!(
        &mut wam,
        "copy_term([X,[Y,[X]]],Term).",
        [["Term = [_12,[_16,[_12]]]", "X = _0", "Y = _4"]]
    );

    // test copy_term on cyclic terms.
    assert_prolog_failure!(&mut wam, "X = g(X,Y),Y = f(X),copy_term(Y,g(Z)).");
    assert_prolog_success!(
        &mut wam,
        "X = g(X,Y),Y = f(X),copy_term(Y,f(Z)).",
        [["Y = f(g(X,Y))", "X = g(X,f(X))", "Z = g(Z,f(Z))"]]
    );
    assert_prolog_success!(
        &mut wam,
        "X = g(X,Y),Y = f(X),copy_term(Y,V).",
        [[
            "V = f(g(g(g(...,V),V),V))",
            "X = g(X,f(X))",
            "Y = f(g(X,Y))"
        ]]
    );
    assert_prolog_success!(
        &mut wam,
        "f(Y,Y,[X,a,[],Y]) = Term,copy_term(Term,NewTerm).",
        [[
            "NewTerm = f(_16,_16,[_19,a,[],_16])",
            "Term = f(_0,Y,[_6,a,[],Y])",
            "X = _6",
            "Y = _0"
        ]]
    );

    assert_prolog_success!(&mut wam, "float(3.14159269).");
    assert_prolog_failure!(&mut wam, "float(3).");
    assert_prolog_failure!(&mut wam, "float(\"sdfsa\").");
    assert_prolog_failure!(&mut wam, "float(atom).");
    assert_prolog_failure!(&mut wam, "float(structure(functor)).");
    assert_prolog_failure!(&mut wam, "float([1,2,3]).");
    assert_prolog_failure!(&mut wam, "float([1,2,X]).");
    assert_prolog_failure!(&mut wam, "X is 3 rdiv 4,float(X).");

    assert_prolog_success!(&mut wam, "X is 3 rdiv 4,rational(X).");
    assert_prolog_failure!(&mut wam, "rational(3).");
    assert_prolog_failure!(&mut wam, "rational(f(X)).");
    assert_prolog_failure!(&mut wam, "rational(\"sdfsa\").");
    assert_prolog_failure!(&mut wam, "rational(atom).");
    assert_prolog_failure!(&mut wam, "rational(structure(functor)).");
    assert_prolog_failure!(&mut wam, "rational([1,2,3]).");
    assert_prolog_failure!(&mut wam, "rational([1,2,X]).");

    assert_prolog_success!(&mut wam, "compound(functor(compound)).");
    assert_prolog_success!(&mut wam, "compound(f(X)).");
    assert_prolog_success!(&mut wam, "compound([1,2,3]).");
    assert_prolog_failure!(&mut wam, "compound([]).");
    assert_prolog_failure!(&mut wam, "compound(3.14159269).");
    assert_prolog_failure!(&mut wam, "compound(3).");
    assert_prolog_failure!(&mut wam, "compound(\"sdfsa\").");
    assert_prolog_failure!(&mut wam, "compound(atom).");

    assert_prolog_failure!(&mut wam, "string(functor(string)).");
    assert_prolog_failure!(&mut wam, "string(3.14159269).");
    assert_prolog_failure!(&mut wam, "string(3).");
    assert_prolog_failure!(&mut wam, "string(f(X)).");
    assert_prolog_success!(&mut wam, "string(\"sdfsa\").");
    assert_prolog_failure!(&mut wam, "string(atom).");
    assert_prolog_failure!(&mut wam, "string([1,2,3]).");
    assert_prolog_failure!(&mut wam, "string([1,2,X]).");

    assert_prolog_success!(&mut wam, "X = nonvar,nonvar(X).");
    assert_prolog_failure!(&mut wam, "nonvar(X).");
    assert_prolog_success!(&mut wam, "nonvar(f(X)).");
    assert_prolog_success!(&mut wam, "nonvar(functor(nonvar)).");
    assert_prolog_success!(&mut wam, "nonvar(3.14159269).");
    assert_prolog_success!(&mut wam, "nonvar(3).");
    assert_prolog_success!(&mut wam, "nonvar(\"sdfsa\").");
    assert_prolog_success!(&mut wam, "nonvar(atom).");
    assert_prolog_success!(&mut wam, "nonvar([1,2,3]).");
    assert_prolog_success!(&mut wam, "nonvar([1,2,X]).");

    assert_prolog_success!(&mut wam, "A = f(A),ground(f(f(A))),ground(f(A)),ground(A).");
    assert_prolog_failure!(&mut wam, "B = f(A),ground(B).");
    assert_prolog_failure!(&mut wam, "B = f(A),ground(A).");

    assert_prolog_success!(
        &mut wam,
        "ground(x),ground(f(x)),X = f(x),ground(g(f(X),[a,b]))."
    );

    assert_prolog_success!(&mut wam, "A = f(A),g(A,B) == g(f(A),B).");
    assert_prolog_failure!(&mut wam, "A = f(A),g(A,B) == g(f(A),b).");
    assert_prolog_failure!(&mut wam, "A == B.");
    assert_prolog_failure!(&mut wam, "A == 12.1.");
    assert_prolog_success!(&mut wam, "X = x,f(X,x) == f(x,X).");

    assert_prolog_failure!(&mut wam, "A = f(A),g(A,B) \\== g(f(A),B).");
    assert_prolog_success!(&mut wam, "A = f(A),g(A,B) \\== g(f(A),b).");
    assert_prolog_success!(&mut wam, "A \\== B.");
    assert_prolog_success!(&mut wam, "A \\== 12.1.");
    assert_prolog_failure!(&mut wam, "X = x,f(X,x) \\== f(x,X).");

    assert_prolog_success!(&mut wam, "X @=< Y.");
    assert_prolog_failure!(&mut wam, "X @>= Y.");
    assert_prolog_failure!(&mut wam, "X @> Y.");
    assert_prolog_success!(&mut wam, "X @>= X.");
    assert_prolog_failure!(&mut wam, "atom @=< \"string\".");
    assert_prolog_success!(&mut wam, "atom @=< atom.");
    assert_prolog_failure!(&mut wam, "atom @=< aaa.");
    assert_prolog_success!(&mut wam, "atom @>= \"string\".");
    assert_prolog_success!(&mut wam, "X is 3 + 3,X @>= Y.");
    assert_prolog_success!(&mut wam, "f(X) @>= f(X).");
    assert_prolog_success!(&mut wam, "f(X) @>= a.");
    assert_prolog_failure!(&mut wam, "f(X) @=< a.");
    assert_prolog_success!(&mut wam, "[1,2] @=< [1,2].");
    assert_prolog_failure!(&mut wam, "[1,2,3] @=< [1,2].");
    assert_prolog_success!(&mut wam, "[] @=< [1,2].");
    assert_prolog_failure!(&mut wam, "[] @< 1.");
    assert_prolog_failure!(&mut wam, "[] @< \"string\".");
    assert_prolog_failure!(&mut wam, "[] @< atom.");
    assert_prolog_success!(&mut wam, "atom @< [].");
    assert_prolog_success!(&mut wam, "1.1 @< 1.");
    assert_prolog_success!(&mut wam, "1.0 @=< 1.");
    assert_prolog_success!(&mut wam, "1 @=< 1.0.");

    submit(&mut wam, ":- use_module(library(non_iso)).");

    assert_prolog_success!(&mut wam, "variant(X, Y).");
    assert_prolog_failure!(&mut wam, "variant(f(X), f(x)).");
    assert_prolog_success!(&mut wam, "variant(X, X).");
    assert_prolog_success!(&mut wam, "variant(f(x), f(x)).");
    assert_prolog_failure!(&mut wam, "variant([X,Y,Z], [V,W,V]).");
    assert_prolog_success!(&mut wam, "variant([X,Y,Z], [V,W,Z]).");
    assert_prolog_success!(&mut wam, "variant([X,Y,X], [V,W,V]).");
    assert_prolog_success!(&mut wam, "g(B) = B, g(A) = A, variant(A, B).");

    assert_prolog_success!(
        &mut wam,
        "keysort([1-1,1-1],Sorted).",
        [["Sorted = [1-1,1-1]"]]
    );
    assert_prolog_success!(
        &mut wam,
        "keysort([2-99,1-a,3-f(_),1-z,1-a,2-44],Sorted).",
        [["Sorted = [1-a,1-z,1-a,2-99,2-44,3-f(_7)]"]]
    );
    assert_prolog_success!(&mut wam, "keysort([X-1,1-1],[2-1,1-1]).", [["X = 2"]]);

    assert_prolog_failure!(&mut wam, "Pairs = [a-a|Pairs],keysort(Pairs,_).");
    assert_prolog_success!(
        &mut wam,
        "Pairs = [a-a|Pairs],catch(keysort(Pairs,_),error(E,_),true).",
        [[
            "E = type_error(list,[a-a,a-a,a-a|...])",
            "Pairs = [a-a|Pairs]"
        ]]
    );

    assert_prolog_success!(&mut wam, "keysort([],L).", [["L = []"]]);
    assert_prolog_success!(
        &mut wam,
        "catch(keysort([a|_],_),error(E,_),true).",
        [["E = instantiation_error"]]
    );
    assert_prolog_success!(
        &mut wam,
        "catch(keysort([],[a|a]),error(Pat,_),true).",
        [["Pat = type_error(list,[a|a])"]]
    );
    assert_prolog_success!(
        &mut wam,
        "catch(keysort(_,_),error(E,_),true).",
        [["E = type_error(list,_16)"]]
    );
    assert_prolog_success!(
        &mut wam,
        "catch(keysort([a-1],[_|b]),error(E,_),true).",
        [["E = type_error(list,[_27|b])"]]
    );
    assert_prolog_success!(
        &mut wam,
        "catch(keysort([a-1],[a-b,c-d,a]),error(E,_),true).",
        [["E = type_error(pair,a)"]]
    );
    assert_prolog_success!(
        &mut wam,
        "catch(keysort([a],[a-b]),error(E,_),true).",
        [["E = type_error(pair,a)"]]
    );

    assert_prolog_success!(
        &mut wam,
        "catch(sort([a|_],_),error(E,_),true).",
        [["E = instantiation_error"]]
    );
    assert_prolog_success!(
        &mut wam,
        "catch(sort([],[a|a]),error(Pat,_),true).",
        [["Pat = type_error(list,[a|a])"]]
    );
    assert_prolog_success!(&mut wam, "sort([],L).", [["L = []"]]);
    assert_prolog_success!(
        &mut wam,
        "catch(sort(_,[]),error(E,_),true).",
        [["E = type_error(list,_16)"]]
    );
    assert_prolog_success!(
        &mut wam,
        "catch(sort([a,b,c],not_a_list),error(E,_),true).",
        [["E = type_error(list,not_a_list)"]]
    );

    assert_prolog_success!(
        &mut wam,
        "call(((G = 2 ; fail),B=3,!)).",
        [["G = 2", "B = 3"]]
    );

    assert_prolog_success!(&mut wam, "call_with_inference_limit((setup_call_cleanup(S=1,(G=2;fail),writeq(S+G>B)),B=3,!),135,R).",
                           [["G = 2","B = 3","R = !","S = 1"]]);
    assert_prolog_success!(
        &mut wam,
        "call_with_inference_limit((setup_call_cleanup(S=1,(G=2;fail),writeq(S+G>B)),B=3,!),10,R).",
        [[
            "S = _1",
            "G = _4",
            "B = _14",
            "R = inference_limit_exceeded"
        ]]
    );

    assert_prolog_success!(&mut wam, "X = '\\033\\'.", [["X = '\\x1b\\'"]]);

    assert_prolog_success!(&mut wam, "X = '\\n'.", [["X = '\\n'"]]);
    assert_prolog_success!(&mut wam, "X = '\\b'.", [["X = '\\b'"]]);
    assert_prolog_success!(&mut wam, "X = '\\v'.", [["X = '\\v'"]]);
    assert_prolog_success!(&mut wam, "X = '\\a'.", [["X = '\\a'"]]);
    assert_prolog_success!(&mut wam, "X = '\\f'.", [["X = '\\f'"]]);
    assert_prolog_success!(
        &mut wam,
        "X = '\\b\\r\\f\\t\\n'.",
        [["X = '\\b\\r\\f\\t\\n'"]]
    );

    assert_prolog_success!(&mut wam, "(- (1)) = -(1).");
    assert_prolog_success!(&mut wam, "(- -1) = -(-1).");

    assert_prolog_success!(&mut wam, "X = ((*)=(*)).", [["X = ((*)=(*))"]]);
    assert_prolog_success!(
        &mut wam,
        "X = [.,.(.,.,.)].",
        [["X = ['.','.'('.','.','.')]"]]
    );
    assert_prolog_success!(&mut wam, "X = a+(b*c).", [["X = a+b*c"]]);
    assert_prolog_success!(&mut wam, "X = a*(b+c).", [["X = a*(b+c)"]]);
    assert_prolog_success!(&mut wam, "X = [:-,-].", [["X = [:-,-]"]]);
    assert_prolog_success!(&mut wam, "X = a*(b+c).", [["X = a*(b+c)"]]);
    assert_prolog_success!(&mut wam, "X = (-)-(-).", [["X = (-)-(-)"]]);
    assert_prolog_success!(&mut wam, "X = ((:-):-(:-)).", [["X = ((:-):-(:-))"]]);
    assert_prolog_success!(&mut wam, "X = (a:-b,c).", [["X = (a:-b,c)"]]);
    assert_prolog_success!(&mut wam, "X = f((f:-a,b,c)).", [["X = f((f:-a,b,c))"]]);
    assert_prolog_success!(&mut wam, "X = f((f:-a,(b,c))).", [["X = f((f:-a,b,c))"]]);
    assert_prolog_success!(&mut wam, "X = f((a,b,c)).", [["X = f((a,b,c))"]]);
    assert_prolog_success!(&mut wam, "X = f((a,(b,c))).", [["X = f((a,b,c))"]]);
    assert_prolog_success!(&mut wam, "X = f(((a,b),c)).", [["X = f(((a,b),c))"]]);
    assert_prolog_success!(&mut wam, "X = f(((a,b),(c,d))).", [["X = f(((a,b),c,d))"]]);

    assert_prolog_success!(
        &mut wam,
        "findall(X,(X = 1 ; X = 2),S).",
        [["S = [1,2]", "X = _0"]]
    );
    assert_prolog_success!(
        &mut wam,
        "findall(X+Y,(X = 1),S).",
        [["S = [1+_36]", "X = _1", "Y = _2"]]
    );
    assert_prolog_success!(&mut wam, "findall(X,false,S).", [["S = []", "X = _0"]]);
    assert_prolog_success!(
        &mut wam,
        "findall(X,(X = 1 ; X = 1),S).",
        [["S = [1,1]", "X = _0"]]
    );
    assert_prolog_failure!(&mut wam, "findall(X,(X = 2 ; X = 1),[1,2]).");
    assert_prolog_success!(
        &mut wam,
        "findall(X,(X = 1 ; X = 2),[X,Y]).",
        [["X = 1", "Y = 2"]]
    );
    assert_prolog_success!(
        &mut wam,
        "catch(findall(X,4,S),error(type_error(callable,4),_),true).",
        [["S = _3", "X = _1"]]
    );

    assert_prolog_success!(
        &mut wam,
        "bagof(X,(X=Y; X=Z),S).",
        [["S = [_3,_6]", "X = _0", "Y = _3", "Z = _6"]]
    );
    assert_prolog_success!(&mut wam, "bagof(X,(X=1 ; X = 2),X).", [["X = [1,2]"]]);
    assert_prolog_success!(
        &mut wam,
        "bagof(X,(X=1 ; X = 2),S).",
        [["S = [1,2]", "X = _0"]]
    );
    assert_prolog_success!(
        &mut wam,
        "bagof(1,(Y=1 ; Y=2),L).",
        [["L = [1]", "Y = 1"], ["L = [1]", "Y = 2"]]
    );

    submit(&mut wam, "b(1,1). b(1,1). b(1,2). b(2,1). b(2,2). b(2,2).");

    assert_prolog_success!(
        &mut wam,
        "bagof(X,b(X,Y),L).",
        [
            ["L = [1,Y,2]", "X = _0", "Y = 1"],
            ["L = [1,2,Y]", "X = _0", "Y = 2"]
        ]
    );

    assert_prolog_success!(
        &mut wam,
        "bagof(X,(X=Y; X=Z; Y=1),L).",
        [
            ["L = [_3,_6]", "X = _0", "Y = _3", "Z = _6"],
            ["L = [_112]", "X = _0", "Y = 1", "Z = _6"]
        ]
    );

    submit(&mut wam, "a(1,f(_)). a(2,f(_)).");

    assert_prolog_success!(
        &mut wam,
        "bagof(X,a(X,Y),L).",
        [["L = [1,2]", "X = _0", "Y = f(_78)"]]
    );

    assert_prolog_success!(
        &mut wam,
        "setof(X,(X = 1 ; X = 2),S).",
        [["S = [1,2]", "X = _0"]]
    );
    assert_prolog_success!(
        &mut wam,
        "setof(X,(X=Y ; X=Z),S).",
        [["S = [_3,_6]", "X = _0", "Y = _3", "Z = _6"]]
    );
    assert_prolog_failure!(&mut wam, "setof(X,false,S).");
    assert_prolog_success!(
        &mut wam,
        "setof(1,(Y=1 ; Y=2),L).",
        [["L = [1]", "Y = 1"], ["L = [1]", "Y = 2"]]
    );
    assert_prolog_success!(
        &mut wam,
        "setof(X,(X=Y; X=Z; Y=1),L).",
        [
            ["L = [_3,_6]", "X = _0", "Y = _3", "Z = _6"],
            ["L = [_112]", "Y = 1", "X = _0", "Y = 1", "Z = _6"]
        ]
    );
    assert_prolog_failure!(
        &mut wam,
        "setof(X,member(X,[f(U,b),f(V,c)]),[f(a,c),f(a,b)])."
    );
    assert_prolog_success!(
        &mut wam,
        "setof(X,member(X,[f(U,b),f(V,c)]),[f(a,b),f(a,c)]).",
        [["U = a", "V = a", "X = _0"]]
    );
    assert_prolog_success!(
        &mut wam,
        "setof(X,member(X,[V,U,f(U),f(V)]),L).",
        [["L = [_2,_4,f(U),f(V)]", "U = _2", "V = _4", "X = _0"]]
    );
    assert_prolog_success!(
        &mut wam,
        "setof(X,member(X,[V,U,f(U),f(V)]),[a,b,f(a),f(b)]).",
        [["U = a", "V = b", "X = _0"]]
    );

    assert_prolog_success!(
        &mut wam,
        "findall(X,(X = 1 ; X = 2),S0,S1).",
        [["S0 = [1,2|_11]", "S1 = _11", "X = _0"]]
    );
    assert_prolog_success!(
        &mut wam,
        "findall(X+Y,(X = 1),S0,S1).",
        [["S0 = [1+_44|_7]", "S1 = _7", "X = _1", "Y = _2"]]
    );
    assert_prolog_success!(&mut wam, "findall(X,false,S,_).", [["S = []", "X = _0"]]);
    assert_prolog_success!(
        &mut wam,
        "findall(X,(X = 1 ; X = 1),S0,S1).",
        [["S0 = [1,1|_11]", "S1 = _11", "X = _0"]]
    );
    assert_prolog_failure!(&mut wam, "findall(X,(X = 2 ; X = 1),[1,2|S],S).");
    assert_prolog_success!(
        &mut wam,
        "findall(X,(X = 1 ; X = 2),[X,Y|S],S).",
        [["S = _11", "X = 1", "Y = 2"]]
    );
    assert_prolog_success!(
        &mut wam,
        "catch(findall(X,4,S0,S1),error(type_error(callable,4),_),true).",
        [["S0 = _3", "S1 = _4", "X = _1"]]
    );

    // bagof & setof with existential variables.
    assert_prolog_success!(
        &mut wam,
        "bagof(X,Y^((X = 1,Y = 1; (X = 2,Y = 2))),S).",
        [["S = [1,2]", "X = _0", "Y = _5"]]
    );
    assert_prolog_success!(
        &mut wam,
        "bagof(X,Y^((X = 1 ; Y = 1) ; (X = 2,Y = 2)),S).",
        [["S = [1,_126,2]", "X = _0", "Y = _5"]]
    );

    assert_prolog_success!(
        &mut wam,
        "setof(X,Y^((X = 1,Y = 1; (X = 2,Y = 2))),S).",
        [["S = [1,2]", "X = _0", "Y = _5"]]
    );
    assert_prolog_success!(
        &mut wam,
        "setof(X,Y^((X = 1 ; Y = 1) ; (X = 2,Y = 2)),S).",
        [["S = [_126,1,2]", "X = _0", "Y = _5"]]
    );

    assert_prolog_failure!(&mut wam, "forall(true,false).");
    assert_prolog_success!(&mut wam, "forall(false,true).");
    assert_prolog_success!(
        &mut wam,
        "catch(forall(_,true),error(instantiation_error,_),true)."
    );
    assert_prolog_success!(
        &mut wam,
        "catch(forall(true,_),error(instantiation_error,_),true)."
    );
    assert_prolog_success!(
        &mut wam,
        "catch(forall(1,true),error(type_error(callable,1),_),true)."
    );
    assert_prolog_success!(
        &mut wam,
        "catch(forall(true,1),error(type_error(callable,1),_),true)."
    );

    submit(
        &mut wam,
        "
:- dynamic(cat/0).
cat.

:- dynamic(dog/0).
dog :- true.

elk(X) :- moose(X).

:- dynamic(legs/2).
legs(A,6) :- insect(A).
legs(A,7) :- A,call(A).

:- dynamic(insect/1).
insect(ant).
insect(bee).",
    );

    assert_prolog_success!(&mut wam, "clause(cat,true).");
    assert_prolog_success!(&mut wam, "clause(dog,true).");
    assert_prolog_success!(
        &mut wam,
        "clause(legs(I,6),Body).",
        [["I = _1", "Body = insect(_1)"]]
    );
    assert_prolog_success!(
        &mut wam,
        "clause(legs(C,7),Body).",
        [["C = _1", "Body = (_1,call(C))"]]
    );
    assert_prolog_success!(
        &mut wam,
        "clause(insect(I),T).",
        [["I = ant", "T = true"], ["I = bee", "T = true"]]
    );
    assert_prolog_failure!(&mut wam, "clause(x,Body).");
    assert_prolog_success!(
        &mut wam,
        "catch(clause(_,_),error(instantiation_error,_),true)."
    );
    assert_prolog_success!(
        &mut wam,
        "catch(clause(4,_),error(type_error(callable,4),_),true)."
    );
    assert_prolog_success!(
        &mut wam,
        "catch(clause(elk(N),_),error(permission_error(access,private_procedure,elk/1),_),true)."
    );
    assert_prolog_success!(
        &mut wam,
        "catch(clause(atom(N),_),error(permission_error(access,private_procedure,atom/1),_),true)."
    );

    assert_prolog_success!(&mut wam, "asserta(legs(octopus,8)).");
    assert_prolog_success!(&mut wam, "asserta( (legs(A,4) :- animal(A)) ).");
    assert_prolog_success!(&mut wam, "asserta( (foo(X) :- X,call(X)) ).");
    assert_prolog_success!(
        &mut wam,
        "catch(asserta(_),error(instantiation_error,_),true)."
    );
    assert_prolog_failure!(&mut wam, "asserta(_).");
    assert_prolog_success!(
        &mut wam,
        "catch(asserta(4),error(type_error(callable,4),_),true)."
    );
    assert_prolog_failure!(&mut wam, "asserta(4).");
    assert_prolog_success!(
        &mut wam,
        "catch(asserta( (foo :- 4) ),error(type_error(callable,4),_),true)."
    );
    assert_prolog_failure!(&mut wam, "asserta( (foo :- 4) ).");
    assert_prolog_success!(&mut wam, "catch(asserta( (atom(_) :- true) ),error(permission_error(modify,static_procedure,atom/1),_),true).");
    assert_prolog_failure!(&mut wam, "asserta( (atom(_) :- true) ).");

    submit(
        &mut wam,
        "
:- dynamic(cat/0).
cat.

:- dynamic(dog/0).
dog :- true.

elk(X) :- moose(X).

:- dynamic(legs/2).
legs(A,6) :- insect(A).
legs(A,7) :- A,call(A).

:- dynamic(insect/1).
insect(ant).
insect(bee).",
    );

    assert_prolog_success!(&mut wam, "assertz(legs(octopus,8)).");
    assert_prolog_success!(&mut wam, "assertz( (legs(A,4) :- animal(A)) ).");
    assert_prolog_success!(&mut wam, "assertz( (foo(X) :- X,call(X)) ).");
    assert_prolog_success!(
        &mut wam,
        "catch(assertz(_),error(instantiation_error,_),true)."
    );
    assert_prolog_failure!(&mut wam, "assertz(_).");
    assert_prolog_success!(
        &mut wam,
        "catch(assertz(4),error(type_error(callable,4),_),true)."
    );
    assert_prolog_failure!(&mut wam, "assertz(4).");
    assert_prolog_success!(
        &mut wam,
        "catch(assertz( (foo :- 4) ),error(type_error(callable,4),_),true)."
    );
    assert_prolog_failure!(&mut wam, "assertz( (foo :- 4) ).");
    assert_prolog_success!(&mut wam, "catch(assertz( (atom(_) :- true) ),error(permission_error(modify,static_procedure,atom/1),_),true).");
    assert_prolog_failure!(&mut wam, "assertz( (atom(_) :- true) ).");

    submit(
        &mut wam,
        "
:- dynamic(legs/2).
legs(A,4) :- animal(A).
legs(octopus,8).
legs(A,6) :- insect(A).
legs(spider,8).
legs(B,2) :- bird(B).

:- dynamic(insect/1).
insect(ant).
insect(bee).

:- dynamic(foo/1).
foo(X) :- call(X),call(X).
foo(X) :- call(X) -> call(X).",
    );

    assert_prolog_success!(&mut wam, "retract(legs(octopus,8)).");
    assert_prolog_failure!(&mut wam, "retract(legs(spider,6)).");
    assert_prolog_success!(
        &mut wam,
        "retract( (legs(X,2) :- T) ).",
        [["X = _1", "T = bird(_1)"]]
    );
    assert_prolog_success!(
        &mut wam,
        "retract( (legs(X,Y) :- Z) ).",
        [
            ["X = _1", "Y = 4", "Z = animal(_1)"],
            ["X = _1", "Y = 6", "Z = insect(_1)"],
            ["X = spider", "Y = 8", "Z = true"]
        ]
    );
    assert_prolog_failure!(&mut wam, "retract( (legs(X,Y) :- Z) ).");
    assert_prolog_success!(&mut wam, "retract(insect(I)).", [["I = ant"], ["I = bee"]]);
    assert_prolog_success!(
        &mut wam,
        "retract(( foo(A) :- A,call(A) )).",
        [["A = call(A)"]]
    );
    assert_prolog_success!(&mut wam, "foo(atom(atom)).");
    assert_prolog_success!(
        &mut wam,
        "retract(( foo(C) :- A -> B )).",
        [["A = call(_1)", "B = call(_1)", "C = _1"]]
    );
    assert_prolog_failure!(&mut wam, "retract( (X :- in_eec(Y)) ).");
    assert_prolog_success!(
        &mut wam,
        "catch(retract( (X :- in_eec(Y)) ),error(instantiation_error,_),true)."
    );
    assert_prolog_failure!(&mut wam, "retract( (4 :- X) ).");
    assert_prolog_success!(
        &mut wam,
        "catch(retract( (4 :- X) ),error(type_error(callable,4),_),true)."
    );
    assert_prolog_failure!(&mut wam, "retract( (atom(X) :- X == '[]') ).");
    assert_prolog_success!(&mut wam, "catch(retract( (atom(X) :- X == '[]') ),error(permission_error(modify,static_procedure,atom/1),_),true).");

    /* This example shows why machine::compile::localize_self_calls is necessary. */
    submit(
        &mut wam,
        "
:- dynamic(p/1).

p(a).
p(b).
p(c) :- p(d).
p(d).",
    );

    assert_prolog_success!(
        &mut wam,
        "p(X),retract(p(_)).",
        [["X = a"], ["X = a"], ["X = a"]]
    );

    submit(
        &mut wam,
        "
:- dynamic(foo/1).
foo(X) :- call(X),call(X).
foo(X) :- call(X) -> call(X).",
    );

    assert_prolog_success!(&mut wam, "abolish(foo/2).");
    assert_prolog_failure!(&mut wam, "abolish(foo/_).");
    assert_prolog_success!(
        &mut wam,
        "catch(abolish(foo/_),error(instantiation_error,abolish/1),true)."
    );
    assert_prolog_failure!(&mut wam, "abolish(foo).");
    assert_prolog_success!(
        &mut wam,
        "catch(abolish(foo),error(type_error(predicate_indicator,foo),abolish/1),true)."
    );
    assert_prolog_failure!(&mut wam, "abolish(foo(_)).");
    assert_prolog_success!(
        &mut wam,
        "catch(abolish(foo(_)),error(type_error(predicate_indicator,foo(_)),abolish/1),true)."
    );
    assert_prolog_failure!(&mut wam, "abolish(abolish/1).");
    assert_prolog_success!(&mut wam, "catch(abolish(abolish/1),error(permission_error(modify,static_procedure,abolish/1),abolish/1),true).");

    assert_prolog_success!(
        &mut wam,
        "atom_length('enchanted evening',N).",
        [["N = 17"]]
    );
    assert_prolog_success!(
        &mut wam,
        r"atom_length('enchanted\
 evening',N).",
        [["N = 17"]]
    );
    assert_prolog_success!(&mut wam, "atom_length('',N).", [["N = 0"]]);
    assert_prolog_failure!(&mut wam, "atom_length('scarlet',5).");
    assert_prolog_success!(
        &mut wam,
        "catch((atom_length(Atom,4),false),error(instantiation_error,_),true)."
    );
    assert_prolog_success!(
        &mut wam,
        "catch((atom_length(1.23,4),false),error(type_error(atom,1.23),_),true)."
    );
    assert_prolog_success!(
        &mut wam,
        "catch((atom_length(atom,'4'),false),error(type_error(integer,'4'),_),true)."
    );
}

#[test]
fn test_queries_on_setup_call_cleanup() {
    let mut wam = Machine::new(readline::input_stream());

    submit(&mut wam, ":- use_module(library(non_iso)).");

    // Test examples from the ISO Prolog page for setup_call_catch.
    assert_prolog_failure!(&mut wam, "setup_call_cleanup(false, _, _).");
    assert_prolog_success!(
        &mut wam,
        "catch(setup_call_cleanup(true, throw(unthrown), _), error(instantiation_error, _), true)."
    );
    assert_prolog_success!(
        &mut wam,
        "setup_call_cleanup(true, true, (true ; throw(x)))."
    );
    assert_prolog_success!(
        &mut wam,
        "setup_call_cleanup(true, X = 1, X = 2).",
        [["X = 1"]]
    );
    assert_prolog_success!(
        &mut wam,
        "setup_call_cleanup(true, true, X = 2).",
        [["X = 2"]]
    );
    assert_prolog_success!(
        &mut wam,
        "catch(setup_call_cleanup(true, X=true, X), error(E, _), true).",
        [["E = instantiation_error", "X = _1"]]
    );
    assert_prolog_success!(
        &mut wam,
        "catch(setup_call_cleanup(X=throw(ex), true, X), E, true).",
        [["E = ex", "X = _3"]]
    );
    assert_prolog_success!(&mut wam, "setup_call_cleanup(true, true, false).");
    assert_prolog_success!(
        &mut wam,
        "setup_call_cleanup(S = 1, G = 2, C = 3).",
        [["S = 1", "G = 2", "C = 3"]]
    );
    assert_prolog_success!(
        &mut wam,
        "setup_call_cleanup((S=1;S=2), G=3, C=4).",
        [["S = 1", "G = 3", "C = 4"]]
    );
    assert_prolog_success!(
        &mut wam,
        "setup_call_cleanup(S=1, G=2, writeq(S+G)).",
        [["S = 1", "G = 2"]]
    );
    assert_prolog_success!(
        &mut wam,
        "setup_call_cleanup(S=1, (G=2;G=3), writeq(S+G)).",
        [["S = 1", "G = 2"], ["S = 1", "G = 3"]]
    );
    assert_prolog_success!(
        &mut wam,
        "setup_call_cleanup(S=1, G=2, writeq(S+G>A+B)), A=3, B=4.",
        [["S = 1", "G = 2", "A = 3", "B = 4"]]
    );
    assert_prolog_success!(
        &mut wam,
        "catch(setup_call_cleanup(S=1, (G=2;G=3,throw(x)), writeq(S+G)), E, true).",
        [["S = 1", "G = 2", "E = _26"], ["G = _4", "E = x", "S = _1"]]
    );
    assert_prolog_success!(
        &mut wam,
        "setup_call_cleanup(S=1, (G=2;G=3),writeq(S+G>B)), B=4, !.",
        [["S = 1", "B = 4", "G = 2"]]
    );
    assert_prolog_success!(
        &mut wam,
        "setup_call_cleanup(S=1,G=2,writeq(S+G>B)),B=3,!.",
        [["S = 1", "G = 2", "B = 3"]]
    );
    assert_prolog_success!(
        &mut wam,
        "setup_call_cleanup(S=1,(G=2;false),writeq(S+G>B)),B=3,!.",
        [["S = 1", "G = 2", "B = 3"]]
    );
    assert_prolog_success!(
        &mut wam,
        "setup_call_cleanup(S=1,(G=2;S=2),writeq(S+G>B)), B=3, !.",
        [["S = 1", "B = 3", "G = 2"]]
    );
    assert_prolog_failure!(
        &mut wam,
        "setup_call_cleanup(S=1,(G=2;G=3), writeq(S+G>B)), B=4, !, throw(x)."
    );

    assert_prolog_success!(
        &mut wam,
        "catch(setup_call_cleanup(true,throw(goal),throw(cl)), Pat, true).",
        [["Pat = goal"]]
    );
    assert_prolog_success!(
        &mut wam,
        "catch(( setup_call_cleanup(true,(G=1;G=2),throw(cl)), throw(cont)), Pat, true).",
        [["Pat = cont", "G = _1"]]
    );

    // fails here.
    assert_prolog_success!(&mut wam,
                           "setup_call_cleanup(true, (X=1;X=2), writeq(a)), setup_call_cleanup(true,(Y=1;Y=2),writeq(b)), !.",
                           [["Y = 1", "X = 1"]]);
}

#[test]
fn test_queries_on_call_with_inference_limit() {
    let mut wam = Machine::new(readline::input_stream());

    submit(&mut wam, ":- use_module(library(non_iso)).");

    assert_prolog_success!(
        &mut wam,
        "call_with_inference_limit(throw(error), 0, R).",
        [["R = inference_limit_exceeded"]]
    );
    assert_prolog_success!(
        &mut wam,
        "catch(call_with_inference_limit(throw(error), 1, R), error, true)."
    );

    assert_prolog_failure!(&mut wam, "call_with_inference_limit(g(X), 5, R).");

    submit(&mut wam, "g(1). g(2). g(3). g(4). g(5).");

    assert_prolog_success!(
        &mut wam,
        "call_with_inference_limit(g(X), 5, R).",
        [
            ["R = true", "X = 1"],
            ["R = true", "X = 2"],
            ["R = true", "X = 3"],
            ["R = true", "X = 4"],
            ["R = !", "X = 5"]
        ]
    );
    assert_prolog_success!(
        &mut wam,
        "call_with_inference_limit(g(X), 5, R), call(true).",
        [
            ["R = true", "X = 1"],
            ["R = true", "X = 2"],
            ["R = true", "X = 3"],
            ["R = true", "X = 4"],
            ["R = !", "X = 5"]
        ]
    );
    assert_prolog_success!(
        &mut wam,
        "call_with_inference_limit(g(X), 2, R).",
        [
            ["R = true", "X = 1"],
            ["R = true", "X = 2"],
            ["R = inference_limit_exceeded", "X = _1"]
        ]
    );
    assert_prolog_success!(
        &mut wam,
        "call_with_inference_limit(g(X), 3, R1),
                                         call_with_inference_limit(g(X), 5, R2).",
        [
            ["X = 1", "R1 = true", "R2 = !"],
            ["X = 2", "R1 = true", "R2 = !"],
            ["X = 3", "R1 = true", "R2 = !"],
            ["X = 4", "R1 = true", "R2 = !"],
            ["X = 5", "R1 = !", "R2 = !"]
        ]
    );

    submit(&mut wam, "f(X) :- call_with_inference_limit(g(X), 5, _).");

    assert_prolog_success!(
        &mut wam,
        "call_with_inference_limit(f(X), 7, R).",
        [
            ["R = true", "X = 1"],
            ["R = true", "X = 2"],
            ["R = true", "X = 3"],
            ["R = true", "X = 4"],
            ["R = !", "X = 5"]
        ]
    );
    assert_prolog_success!(
        &mut wam,
        "call_with_inference_limit(f(X), 6, R).",
        [
            ["R = true", "X = 1"],
            ["R = true", "X = 2"],
            ["R = true", "X = 3"],
            ["R = true", "X = 4"],
            ["R = inference_limit_exceeded", "X = _1"]
        ]
    );
    assert_prolog_success!(
        &mut wam,
        "call_with_inference_limit(f(X), 4, R).",
        [
            ["R = true", "X = 1"],
            ["R = true", "X = 2"],
            ["R = inference_limit_exceeded", "X = _1"]
        ]
    );
    assert_prolog_success!(
        &mut wam,
        "call_with_inference_limit(f(X), 3, R).",
        [
            ["R = true", "X = 1"],
            ["R = inference_limit_exceeded", "X = _1"]
        ]
    );
    assert_prolog_success!(
        &mut wam,
        "call_with_inference_limit(f(X), 2, R).",
        [["R = inference_limit_exceeded", "X = _1"]]
    );

    submit(&mut wam, "e(X) :- call_with_inference_limit(f(X), 10, _).");

    assert_prolog_success!(
        &mut wam,
        "call_with_inference_limit(e(X), 10, R).",
        [
            ["R = true", "X = 1"],
            ["R = true", "X = 2"],
            ["R = true", "X = 3"],
            ["R = true", "X = 4"],
            ["R = !", "X = 5"]
        ]
    );
    assert_prolog_success!(
        &mut wam,
        "call_with_inference_limit(e(X), 8, R).",
        [
            ["R = true", "X = 1"],
            ["R = true", "X = 2"],
            ["R = true", "X = 3"],
            ["R = true", "X = 4"],
            ["R = inference_limit_exceeded", "X = _1"]
        ]
    );
    assert_prolog_success!(
        &mut wam,
        "call_with_inference_limit(e(X), 6, R).",
        [
            ["R = true", "X = 1"],
            ["R = true", "X = 2"],
            ["R = inference_limit_exceeded", "X = _1"]
        ]
    );
    assert_prolog_success!(
        &mut wam,
        "call_with_inference_limit(e(X), 5, R).",
        [
            ["R = true", "X = 1"],
            ["R = inference_limit_exceeded", "X = _1"]
        ]
    );
    assert_prolog_success!(
        &mut wam,
        "call_with_inference_limit(e(X), 4, R).",
        [["R = inference_limit_exceeded", "X = _1"]]
    );

    submit(
        &mut wam,
        "f(X, R) :- call_with_inference_limit(g(X), 5, R).",
    );

    assert_prolog_success!(
        &mut wam,
        "call_with_inference_limit(f(X, R), 4, S).",
        [
            ["S = true", "X = 1", "R = true"],
            ["S = true", "X = 2", "R = true"],
            ["S = inference_limit_exceeded", "X = _1", "R = _2"]
        ]
    );
    assert_prolog_success!(
        &mut wam,
        "call_with_inference_limit(f(X, R), 8, R).",
        [
            ["R = true", "X = 1"],
            ["R = true", "X = 2"],
            ["R = true", "X = 3"],
            ["R = true", "X = 4"],
            ["R = !", "X = 5"]
        ]
    );

    submit(&mut wam, "g(1). g(2). g(3). g(4). g(5). g(6).");

    assert_prolog_success!(
        &mut wam,
        "call_with_inference_limit(f(X, R), 8, S).",
        [
            ["R = true", "X = 1", "S = true"],
            ["R = true", "X = 2", "S = true"],
            ["R = true", "X = 3", "S = true"],
            ["R = true", "X = 4", "S = true"],
            ["R = true", "X = 5", "S = true"],
            ["R = inference_limit_exceeded", "S = !", "X = _1"]
        ]
    );
    assert_prolog_success!(
        &mut wam,
        "call_with_inference_limit(g(X), 2, R), call_with_inference_limit(g(X), 1, S).",
        [
            ["R = true", "X = 1", "S = !"],
            ["R = true", "X = 2", "S = !"],
            ["R = true", "X = 3", "S = !"],
            ["R = true", "X = 4", "S = !"],
            ["R = true", "X = 5", "S = !"],
            ["R = !", "X = 6", "S = !"]
        ]
    );
    assert_prolog_success!(
        &mut wam,
        "call_with_inference_limit(g(X), 2, R), call_with_inference_limit(g(X), 1, R).",
        [["R = !", "X = 6"]]
    );
    assert_prolog_success!(
        &mut wam,
        "call_with_inference_limit(g(X), 1, R), call_with_inference_limit(g(X), 1, R).",
        [["R = inference_limit_exceeded", "X = _1"]]
    );
}

#[test]
fn test_queries_on_dcgs() {
    let mut wam = Machine::new(readline::input_stream());

    submit(&mut wam, ":- use_module(library(dcgs)).");

    // test case by YeGoblynQueene from hacker news.
    submit_code(
        &mut wam,
        " ability(destroy, X) --> destroy(X).
      destroy(X) --> [destroy], target(X).
      target(X) --> [target], permanent(X).
      permanent(X) --> [creature], creature(X).
      permanent(X) --> [artifact], artifact(X).
      permanent(X) --> [land], land(X).
      spell(X) --> [sorcery], sorcery(X).
      spell(X) --> [instant], instant(X).

      creature('Llanowar Elves') --> [].
      artifact('Ankh of Mishra') --> [].
      land('Mountain') --> [].
      % etc permanents
      sorcery('Duress') --> [].
      instant('Lightning Bolt') --> [].",
    );

    assert_prolog_success!(
        &mut wam,
        "phrase(ability(destroy, X), P).",
        [
            ["P = [destroy,target,creature]", "X = 'Llanowar Elves'"],
            ["P = [destroy,target,artifact]", "X = 'Ankh of Mishra'"],
            ["P = [destroy,target,land]", "X = 'Mountain'"]
        ]
    );
}

#[test]
fn test_queries_on_string_lists() {
    let mut wam = Machine::new(readline::input_stream());

    submit(&mut wam, ":- use_module(library(non_iso)).");

    // double_quotes is chars by default.
    assert_prolog_success!(&mut wam, "variant(\"\", []).");
    assert_prolog_success!(&mut wam, "\"\" == [].");
    assert_prolog_failure!(&mut wam, "\"abc\" == [].");
    assert_prolog_success!(&mut wam, "variant(\"abc\", ['a', 'b', 'c']).");
    assert_prolog_success!(&mut wam, "variant(\"abc\", ['a', 'b', c]).");
    assert_prolog_success!(&mut wam, "variant(\"abc\", ['a', b, 'c']).");
    assert_prolog_success!(&mut wam, "variant(\"abc\", [a, 'b', 'c']).");
    assert_prolog_success!(&mut wam, "variant(\"abc\", [a, 'b', c]).");
    assert_prolog_failure!(&mut wam, "\"abc\" == ['a', 'b', 'c'].");
    assert_prolog_failure!(&mut wam, "\"abc\" == ['a', 'b', c].");
    assert_prolog_failure!(&mut wam, "\"abc\" == ['a', b, 'c'].");
    assert_prolog_failure!(&mut wam, "\"abc\" == [a, 'b', 'c'].");
    assert_prolog_failure!(&mut wam, "\"abc\" == [a, 'b', c].");
    assert_prolog_failure!(&mut wam, "\"koen\" == [k, o, e, n].");
    assert_prolog_success!(&mut wam, "\"koen\" = [k, o, e, n].");
    assert_prolog_success!(&mut wam, "variant(\"koen\", [k, o, e, n]).");
    assert_prolog_success!(&mut wam, "variant(\"koen\", \"koen\").");
    assert_prolog_success!(&mut wam, "\"koen\" = [k, o | X].", [["X = [e,n]"]]);
    assert_prolog_success!(
        &mut wam,
        "\"koen\" = [k, o | X], X = \"en\".",
        [["X = [e,n]"]]
    );
    assert_prolog_failure!(&mut wam, "\"koen\" = [k, o | X], X == \"en\".");
    assert_prolog_success!(
        &mut wam,
        "\"koen\" = [k, o | X], variant(X, \"en\").",
        [["X = [e,n]"]]
    );

    assert_prolog_failure!(&mut wam, "X = \"abc\", Y = \"abc\", X == Y.");
    assert_prolog_failure!(
        &mut wam,
        "partial_string(\"abc\", X), partial_string(\"abc\", Y), X == Y."
    );

    assert_prolog_success!(&mut wam, "X = \"abc\", Y = \"abc\", variant(X, Y).");
    assert_prolog_success!(
        &mut wam,
        "partial_string(\"abc\", X), partial_string(\"abc\", Y), variant(X, Y)."
    );

    submit(&mut wam, "matcher([a,b,c|X], ['d','e','f'|X]).");

    assert_prolog_success!(&mut wam, "matcher(\"abcdef\", \"defdef\").");
    assert_prolog_failure!(&mut wam, "matcher(\"abcdef\", \"defdff\").");

    assert_prolog_success!(
        &mut wam,
        "matcher([X, Y, Z | W], [A, B, C | W]).",
        [["A = d", "B = e", "C = f", "W = _1", "X = a", "Y = b", "Z = c"]]
    );
    assert_prolog_failure!(&mut wam, "matcher([X, Y, Z | W], [X, B, C | W]).");

    submit(&mut wam, "matcher([a,b,c|X], X).");

    assert_prolog_success!(
        &mut wam,
        "matcher(\"abcdef\", X), X = [d,e,f|Y], variant(Y, []), X = \"def\".",
        [["X = [d,e,f]", "Y = []"]]
    );
    assert_prolog_success!(
        &mut wam,
        "matcher(\"abcdef\", X), X = [d,e,f|Y], variant(Y, []), variant(X, \"def\").",
        [["X = [d,e,f]", "Y = []"]]
    );
    assert_prolog_success!(
        &mut wam,
        "X = ['a', 'b', 'c' | \"def\"].",
        [["X = [a,b,c,d,e,f]"]]
    );

    assert_prolog_success!(&mut wam, "X = [a,b,c|\"abc\"].", [["X = [a,b,c,a,b,c]"]]);

    assert_prolog_success!(&mut wam, "set_prolog_flag(double_quotes, atom).");

    assert_prolog_success!(&mut wam, "matcher(X, Y).", [["X = [a,b,c|_1]", "Y = _1"]]);
    assert_prolog_failure!(&mut wam, "matcher(\"abcdef\", Y).");

    assert_prolog_success!(&mut wam, "set_prolog_flag(double_quotes, chars).");

    assert_prolog_success!(
        &mut wam,
        "X = \"abc\", X = ['a' | Y], set_prolog_flag(double_quotes, atom).",
        [["X = \"abc\"", "Y = \"bc\""]]
    );

    // partial strings.
    assert_prolog_success!(&mut wam, "set_prolog_flag(double_quotes, chars).");

    assert_prolog_failure!(&mut wam, "Y = 5, partial_string(\"abc\", Y).");
    assert_prolog_success!(&mut wam, "partial_string(\"abc\", X).", [["X = [a,b,c|_]"]]);

    assert_prolog_failure!(
        &mut wam,
        "partial_string(\"abc\", X), partial_string(\"abc\", Y), matcher(X, V),
                                         matcher(Y, Z), V = Z."
    );

    submit(&mut wam, "matcher([a, b, c | X], X).");

    assert_prolog_success!(
        &mut wam,
        "partial_string(\"abc\", X), matcher(X, Y).",
        [["X = [a,b,c|_]", "Y = _"]]
    );
    assert_prolog_success!(
        &mut wam,
        "partial_string(\"abc\", X), matcher(X, Y), Y = \"def\".",
        [["X = [a,b,c,d,e,f]", "Y = [d,e,f]"]]
    );
    assert_prolog_success!(
        &mut wam,
        "partial_string(\"abc\", X), matcher(X, Y), \"def\" = Y.",
        [["X = [a,b,c,d,e,f]", "Y = [d,e,f]"]]
    );

    assert_prolog_success!(
        &mut wam,
        "partial_string(\"abc\", X), matcher(X, Y), partial_string(\"def\", Y).",
        [["X = [a,b,c,d,e,f|_]", "Y = [d,e,f|_]"]]
    );
    assert_prolog_success!(
        &mut wam,
        "partial_string(\"abc\", X), matcher(X, Y), partial_string(\"def\", Y),
                                         Y = \"defghijkl\".",
        [["X = [a,b,c,d,e,f,g,h,i,j,k,l]", "Y = [d,e,f,g,h,i,j,k,l]"]]
    );

    assert_prolog_success!(
        &mut wam,
        "partial_string(\"abc\", X), matcher(X, Y), Y = [d, e, f | G].",
        [["X = [a,b,c,d,e,f|_]", "Y = [d,e,f|_]", "G = _"]]
    );
    assert_prolog_success!(
        &mut wam,
        "partial_string(\"abc\",X),matcher(X,Y),[d,e,f | G] = Y.",
        [["X = [a,b,c,d,e,f|_]", "Y = [d,e,f|_]", "G = _"]]
    );
    assert_prolog_success!(
        &mut wam,
        "partial_string(\"abc\",X),matcher(X,Y),Y = [d,e,f | G], G = \"ghi\".",
        [[
            "X = [a,b,c,d,e,f,g,h,i]",
            "Y = [d,e,f,g,h,i]",
            "G = [g,h,i]"
        ]]
    );
    assert_prolog_success!(
        &mut wam,
        "partial_string(\"abc\",X),matcher(X,Y),Y = [d,e,f | G],
                                         is_partial_string(Y),G = \"ghi\".",
        [[
            "X = [a,b,c,d,e,f,g,h,i]",
            "Y = [d,e,f,g,h,i]",
            "G = [g,h,i]"
        ]]
    );
    assert_prolog_success!(
        &mut wam,
        "partial_string(\"abc\",X),matcher(X,Y),Y = [d,e,f | G],
                                         is_partial_string(Y),is_partial_string(G),G = \"ghi\".",
        [[
            "X = [a,b,c,d,e,f,g,h,i]",
            "Y = [d,e,f,g,h,i]",
            "G = [g,h,i]"
        ]]
    );
    assert_prolog_success!(
        &mut wam,
        "partial_string(\"abc\",X),partial_string(\"ababc\",Y),Y = [a,b|Z],
                                      variant(X, Z).",
        [["X = [a,b,c|_]", "Y = [a,b,a,b,c|_]", "Z = [a,b,c|_]"]]
    );
    assert_prolog_failure!(
        &mut wam,
        "partial_string(\"abc\",X),partial_string(\"ababc\",Y),Y = [a,b|Z],
                                      X == Z."
    );

    assert_prolog_success!(&mut wam, "partial_string(\"abc\",X), X @> \"abc\".");
    assert_prolog_failure!(
        &mut wam,
        "partial_string(\"abc\",X), \\+ variant(X, \"abc\")."
    );
    assert_prolog_failure!(&mut wam, "partial_string(\"abc\",X), X @< \"abc\".");

    assert_prolog_success!(
        &mut wam,
        "partial_string(\"ab\",X),matcher(X,Y),Y = [a,b|V],
                                         matcher(Y,Z),is_partial_string(Y).",
        [["V = [c|_]", "X = [a,b,c,a,b,c|_]", "Y = [a,b,c|_]", "Z = _"]]
    );
    assert_prolog_success!(
        &mut wam,
        "partial_string(\"a\",X),matcher(X,Y).",
        [["X = [a,b,c|_]", "Y = _"]]
    );
    assert_prolog_success!(
        &mut wam,
        "partial_string(\"a\",X),matcher(X,Y),is_partial_string(Y).",
        [["X = [a,b,c|_]", "Y = _"]]
    );
    assert_prolog_success!(
        &mut wam,
        "partial_string(\"a\",X),matcher(X,Y),Y = \"def\".",
        [["X = [a,b,c,d,e,f]", "Y = [d,e,f]"]]
    );

    submit(
        &mut wam,
        "matcher([a,b,c|X],X).
                      matcher([a,b,d|X],X).",
    );

    assert_prolog_success!(
        &mut wam,
        "partial_string(\"ab\",X),matcher(X,Y).",
        [["X = [a,b,c|_]", "Y = _"], ["X = [a,b,d|_]", "Y = _"]]
    );

    submit(
        &mut wam,
        "matcher([a,b,c,d|X],X).
                      matcher([a,c,d|X],X).",
    );

    assert_prolog_success!(
        &mut wam,
        "partial_string(\"ab\",X),matcher(X,Y).",
        [["X = [a,b,c,d|_]", "Y = _"]]
    );

    assert_prolog_success!(
        &mut wam,
        "partial_string(\"a\",X),matcher(X,Y).",
        [["X = [a,b,c,d|_]", "Y = _"], ["X = [a,c,d|_]", "Y = _"]]
    );

    submit(
        &mut wam,
        "matcher([a,b,c,d|X],X).
                      matcher([a,c,d|X],X).
                      matcher([a,e,f|X],X).",
    );

    assert_prolog_success!(
        &mut wam,
        "partial_string(\"a\",X),matcher(X,Y).",
        [
            ["X = [a,b,c,d|_]", "Y = _"],
            ["X = [a,c,d|_]", "Y = _"],
            ["X = [a,e,f|_]", "Y = _"]
        ]
    );
    assert_prolog_success!(
        &mut wam,
        "partial_string(\"a\",X),matcher(X,Y),Y = \" t\".",
        [
            ["X = [a,b,c,d,' ',t]", "Y = [' ',t]"],
            ["X = [a,c,d,' ',t]", "Y = [' ',t]"],
            ["X = [a,e,f,' ',t]", "Y = [' ',t]"]
        ]
    );

    submit(
        &mut wam,
        "matcher([a,b,c|X],X) :- X = [].
                      matcher([a,b,c|X],X).",
    );

    assert_prolog_success!(
        &mut wam,
        "partial_string(\"abc\",X),matcher(X,Y).",
        [["X = [a,b,c]", "Y = []"], ["X = [a,b,c|_]", "Y = _"]]
    );
    assert_prolog_success!(
        &mut wam,
        "partial_string(\"a\",X),matcher(X,Y).",
        [["X = [a,b,c]", "Y = []"], ["X = [a,b,c|_]", "Y = _"]]
    );

    assert_prolog_failure!(
        &mut wam,
        "partial_string(\"abc\",X),partial_string(\"bc\",Y),X = [a|Y]."
    );

    submit(
        &mut wam,
        "matcher([a|X],X) :- matcher2(X,_).
                      matcher([b|X],X) :- matcher2(X,_).

                      matcher2([c|X],X).
                      matcher2([d|X],X).",
    );

    assert_prolog_success!(
        &mut wam,
        "partial_string(\"\",X),matcher(X,Y).",
        [
            ["X = [a,c|_]", "Y = [c|_]"],
            ["X = [a,d|_]", "Y = [d|_]"],
            ["X = [b,c|_]", "Y = [c|_]"],
            ["X = [b,d|_]", "Y = [d|_]"]
        ]
    );
    assert_prolog_success!(
        &mut wam,
        "partial_string(\"a\",X),matcher(X,Y).",
        [["X = [a,c|_]", "Y = [c|_]"], ["X = [a,d|_]", "Y = [d|_]"]]
    );
    assert_prolog_success!(
        &mut wam,
        "partial_string(\"b\",X),matcher(X,Y).",
        [["X = [b,c|_]", "Y = [c|_]"], ["X = [b,d|_]", "Y = [d|_]"]]
    );
    assert_prolog_success!(
        &mut wam,
        "partial_string(\"bc\",X),matcher(X,Y).",
        [["X = [b,c|_]", "Y = [c|_]"]]
    );

    submit(
        &mut wam,
        "f(\"appendy jones\").
                      f(\"appendy smithers jones\").
                      f(\"appendy o'toole\").",
    );

    assert_prolog_success!(
        &mut wam,
        "partial_string(\"appendy\",X),f(X).",
        [
            ["X = [a,p,p,e,n,d,y,' ',j,o,n,e,s]"],
            ["X = [a,p,p,e,n,d,y,' ',s,m,i,t,h,e,r,s,' ',j,o,n,e,s]"],
            ["X = [a,p,p,e,n,d,y,' ',o,'\\'',t,o,o,l,e]"]
        ]
    );

    assert_prolog_success!(
        &mut wam,
        "partial_string(\"abc\",X),partial_string(\"abcdef\",X).",
        [["X = [a,b,c,d,e,f|_]"]]
    );
    assert_prolog_success!(
        &mut wam,
        "partial_string(\"abc\",X),partial_string(\"abcdef\",X),X = \"abcdef\".",
        [["X = [a,b,c,d,e,f]"]]
    );
}

#[test]
fn test_queries_on_attributed_variables() {
    let mut wam = Machine::new(readline::input_stream());

    submit(
        &mut wam,
        "
:- module(my_mod, []).
:- use_module(library(atts)).

:- attribute dif/1, frozen/1.",
    );

    assert_prolog_success!(
        &mut wam,
        "( put_atts(V, my_mod, dif(1)) ; put_atts(V, my_mod, dif(2)) ), get_atts(V, my_mod, L).",
        [["L = [dif(1)]", "V = _10"], ["L = [dif(2)]", "V = _10"]]
    );

    assert_prolog_success!(
        &mut wam,
        "put_atts(V, my_mod, frozen(a)),
   				       ( put_atts(V, my_mod, dif(1))
   				       ; put_atts(V, my_mod, -frozen(a)), put_atts(V, my_mod, dif(2))
   				       ; put_atts(V, my_mod, dif(different)) ),
   				       get_atts(V, my_mod, Ls).",
        [
            ["Ls = [frozen(a),dif(1)]", "V = _10"],
            ["Ls = [dif(2)]", "V = _10"],
            ["Ls = [frozen(a),dif(different)]", "V = _10"]
        ]
    );

    assert_prolog_success!(
        &mut wam,
        "put_atts(V, my_mod, [dif(1), dif(2), frozen(a)]),
   				       ( put_atts(V, my_mod, -dif(2)); put_atts(V, my_mod, -frozen(A)) ),
   				  	 get_atts(V, my_mod, L).",
        [
            ["A = _71", "L = [frozen(a)]", "V = _25"],
            ["A = _71", "L = [dif(2)]", "V = _25"]
        ]
    );
    assert_prolog_success!(
        &mut wam,
        "put_atts(V, my_mod, [dif(1), dif(2), frozen(a), frozen(b)]),
   				       ( put_atts(V, my_mod, -dif(2)) ; put_atts(V, my_mod, -frozen(A)) ),
   				  	 get_atts(V, my_mod, L).",
        [
            ["A = _111", "L = [frozen(b)]", "V = _29"],
            ["A = _111", "L = [dif(2)]", "V = _29"]
        ]
    );
    assert_prolog_success!(
        &mut wam,
        "put_atts(V, my_mod, [dif(1), dif(2), frozen(a), frozen(b)]),
                                         get_atts(V, my_mod, -dif(1))."
    );
    assert_prolog_success!(
        &mut wam,
        "put_atts(V, my_mod, [dif(1), dif(2), frozen(a), frozen(b)]),
                                         get_atts(V, my_mod, -dif(3))."
    );
    assert_prolog_success!(
        &mut wam,
        "put_atts(V, my_mod, [dif(1), dif(2), frozen(a), frozen(b)]),
                                         get_atts(V, my_mod, dif(X)).",
        [["X = 2", "V = _29"]]
    );
    assert_prolog_success!(
        &mut wam,
        "put_atts(V, my_mod, [dif(1), dif(2), frozen(a), frozen(b)]),
                                         put_atts(V, my_mod, -dif(A)), get_atts(V, my_mod, Ls).",
        [["A = _112", "Ls = [frozen(b)]", "V = _29"]]
    );
    assert_prolog_success!(
        &mut wam,
        "put_atts(V, my_mod, [dif(1), frozen(a), dif(2), frozen(b)]),
                                         put_atts(V, my_mod, -dif(A)), get_atts(V, my_mod, Ls).",
        [["A = _114", "Ls = [frozen(b)]", "V = _29"]]
    );

    submit(
        &mut wam,
        ":- use_module('src/prolog/examples/minatotask.pl').",
    );

    assert_prolog_failure!(
        &mut wam,
        "ZDD = ( X -> b(true) ; ( Y -> b(true) ; b(false) ) ),
                                         Vs = [X,Y],
                                         variables_set_zdd(Vs, ZDD),
                                         Vs = [1,1]."
    );
    assert_prolog_success!(
        &mut wam,
        "ZDD = ( X -> b(true) ; ( Y -> b(true) ; b(false) ) ),
      					 Vs = [X,Y],
      					 variables_set_zdd(Vs, ZDD),
      					 X = 1.",
        [[
            "X = 1",
            "Y = 0",
            "Vs = [1,0]",
            "ZDD = (1->b(true);0->b(true);b(false))"
        ]]
    );
    assert_prolog_success!(
        &mut wam,
        "ZDD = ( X -> b(true) ; ( Y -> b(true) ; b(false) ) ),
      					 Vs = [X,Y],
      					 variables_set_zdd(Vs, ZDD),
      					 X = 0.",
        [[
            "Vs = [0,_58]",
            "X = 0",
            "Y = _58",
            "ZDD = (0->b(true);_58->b(true);b(false))"
        ]]
    );
}