add ffi tests using f64

tests-pl/ffi_f64_minus_zero.pl

@@ -0,0 +1,16 @@
+:- use_module(library(os)).
+:- use_module(library(ffi)).
+
+test :- 
+    getenv("ffi_f64_minus_zero_LIB", LIB),    
+    use_foreign_module(LIB, ['ffi_f64_minus_zero'([], f64), 'signum'([f64], f64)]),
+    ffi:'ffi_f64_minus_zero'(N),
+    A is max(0.0, N),
+    B is max(N, 0.0),
+    ffi:'signum'(A, SA),
+    ffi:'signum'(B, SB),
+    write((SA, SB)),
+    -1.0 is SA, % incorrect, based on https://www.swi-prolog.org/pldoc/man?function=max/2 -0.0 is less than 0.0 so A and B should be 0.0 for which signum should be 1
+    1.0 is SB.
+
+:- initialization(test).

tests-pl/ffi_f64_nan.pl

@@ -0,0 +1,10 @@
+:- use_module(library(os)).
+:- use_module(library(ffi)).
+
+test :- 
+    getenv("ffi_f64_nan_LIB", LIB),    
+    use_foreign_module(LIB, ['ffi_f64_nan'([], f64)]),
+    ffi:'ffi_f64_nan'(N),
+    _ is round(N).
+
+:- initialization(test).

tests/scryer/ffi.rs

@@ -0,0 +1,101 @@
+use std::{
+    env::consts::{DLL_PREFIX, DLL_SUFFIX},
+    io::Write,
+    path::Path,
+    process::Stdio,
+};
+
+use crate::helper::load_module_test;
+
+#[test]
+fn ffi_f64_nan() {
+    let tmp_dir: &Path = env!("CARGO_TARGET_TMPDIR").as_ref();
+    println!("CARGO_TARGET_TMPDIR: {tmp_dir:?}");
+
+    // technically UB as tests are by default multi-threaded,
+    // but there is currently no other easy way to get the dynamic library file path as an input into a load_module_test test
+    std::env::set_var(
+        "ffi_f64_nan_LIB",
+        tmp_dir.join(format!("{DLL_PREFIX}ffi_f64_nan{DLL_SUFFIX}")),
+    );
+
+    let mut child = std::process::Command::new("rustc")
+        .stdin(Stdio::piped())
+        .arg("--crate-type=dylib")
+        .arg("--crate-name=ffi_f64_nan")
+        .arg("--out-dir")
+        .arg(tmp_dir)
+        .arg("-")
+        .spawn()
+        .unwrap();
+
+    child
+        .stdin
+        .take()
+        .unwrap()
+        .write_all(
+            r##"
+        #[no_mangle]
+        extern "C" fn ffi_f64_nan() -> f64 {
+            f64::NAN
+        }
+    "##
+            .as_bytes(),
+        )
+        .unwrap();
+
+    assert!(child.wait().unwrap().success());
+
+    load_module_test(
+        "tests-pl/ffi_f64_nan.pl",
+        "   error(evaluation_error(undefined),round/1).\n",
+    );
+}
+
+#[test]
+fn ffi_f64_minus_zero() {
+    let tmp_dir: &Path = env!("CARGO_TARGET_TMPDIR").as_ref();
+    println!("CARGO_TARGET_TMPDIR: {tmp_dir:?}");
+
+    // technically UB as tests are by default multi-threaded,
+    // but there is currently no other easy way to get the dynamic library file path as an input into a load_module_test test
+    std::env::set_var(
+        "ffi_f64_minus_zero_LIB",
+        tmp_dir.join(format!("{DLL_PREFIX}ffi_f64_minus_zero{DLL_SUFFIX}")),
+    );
+
+    let mut child = std::process::Command::new("rustc")
+        .stdin(Stdio::piped())
+        .arg("--crate-type=dylib")
+        .arg("--crate-name=ffi_f64_minus_zero")
+        .arg("--out-dir")
+        .arg(tmp_dir)
+        .arg("-")
+        .spawn()
+        .unwrap();
+
+    child
+        .stdin
+        .take()
+        .unwrap()
+        .write_all(
+            r##"
+        #[no_mangle]
+        extern "C" fn ffi_f64_minus_zero() -> f64 {
+            -0.0
+        }
+
+        #[no_mangle]
+        extern "C" fn signum(f: f64) -> f64 {
+            f.signum()
+        }
+    "##
+            .as_bytes(),
+        )
+        .unwrap();
+
+    assert!(child.wait().unwrap().success());
+
+    // note: ouput is currently wrong correct would be 1.0,1.0
+    load_module_test("tests-pl/ffi_f64_minus_zero.pl", "-1.0,1.0");
+}

tests/scryer/main.rs

@@ -2,6 +2,8 @@ mod helper;
 mod issues;
 mod src_tests;
 
+mod ffi;
+
 /// To add new cli test copy an existing .toml file in `tests/scryer/cli/issues/` or `tests/scryer/cli/issues/src_tests/`,
 /// adjust as necessary the `-f` and `--no-add-history` args should be kept but additional args may be added.
 /// For input on stdin add a .stdin file with the same filename.