clean up tests/

give helper function a more descriptive name

tests/scryer/helper.rs

@@ -0,0 +1,84 @@
+use assert_cmd::Command;
+use std::ffi::OsStr;
+
+pub(crate) trait Expectable {
+    #[track_caller]
+    fn assert_eq(self, other: &[u8]);
+}
+
+impl Expectable for &str {
+    #[track_caller]
+    fn assert_eq(self, other: &[u8]) {
+        if let Ok(other_str) = std::str::from_utf8(other) {
+            assert_eq!(other_str, self)
+        } else {
+            // should always fail as other is not valid utf-8 but self is
+            // just for consistent assert error message
+            assert_eq!(other, self.as_bytes())
+        }
+    }
+}
+
+impl Expectable for &[u8] {
+    #[track_caller]
+    fn assert_eq(self, other: &[u8]) {
+        assert_eq!(other, self)
+    }
+}
+
+/// Tests whether the file can be successfully loaded
+/// and produces the expected output during it
+pub(crate) fn load_module_test<T: Expectable>(file: &str, expected: T) {
+    use scryer_prolog::*;
+
+    let input = machine::Stream::from("");
+    let output = machine::Stream::from(String::new());
+
+    let mut wam = machine::Machine::new(input, output.clone());
+
+    wam.load_file(
+        file.into(),
+        machine::Stream::from(
+            std::fs::read_to_string(AsRef::<std::path::Path>::as_ref(file)).unwrap(),
+        ),
+    );
+
+    let output = output.bytes().unwrap();
+    expected.assert_eq(output.as_slice());
+}
+
+pub const SCRYER_PROLOG: &str = "scryer-prolog";
+
+pub fn run_top_level_test_no_args<
+    S: Into<Vec<u8>>,
+    O: assert_cmd::assert::IntoOutputPredicate<P>,
+    P: predicates_core::Predicate<[u8]>,
+>(
+    stdin: S,
+    expected_stdout: O,
+) {
+    run_top_level_test_with_args::<&[&str], _, _, _, _>(&[], stdin, expected_stdout)
+}
+
+/// Test whether scryr-prolog
+/// produces the expected output when called with the supplied
+/// arguments and fed the supplied input
+pub fn run_top_level_test_with_args<
+    A: IntoIterator<Item = AS>,
+    S: Into<Vec<u8>>,
+    O: assert_cmd::assert::IntoOutputPredicate<P>,
+    AS: AsRef<OsStr>,
+    P: predicates_core::Predicate<[u8]>,
+>(
+    args: A,
+    stdin: S,
+    expected_stdout: O,
+) {
+    Command::cargo_bin(SCRYER_PROLOG)
+        .unwrap()
+        .args(args)
+        .write_stdin(stdin)
+        .assert()
+        .stdout(expected_stdout.into_output())
+        .success();
+}