refactor: move embedded tests into dedicated test directory

tests/unit/battery_macos.rs

@@ -0,0 +1,32 @@
+unsafe extern "C" {
+    fn CFNumberCreate(allocator: Object, kind: isize, value: Object) -> Object;
+}
+
+use super::*;
+
+#[test]
+fn native_values_are_type_checked_and_numbers_must_be_exact_and_nonnegative() {
+    assert!(Owned::new(std::ptr::null()).is_none());
+    unsafe {
+        assert_eq!(number(std::ptr::null()), None);
+        let text = Owned::string(c"27").unwrap();
+        assert_eq!(number(text.0), None);
+        for value in [-1_i64, 0, 100] {
+            let object = Owned::new(CFNumberCreate(
+                std::ptr::null(),
+                4,
+                (&value as *const i64).cast(),
+            ))
+            .unwrap();
+            assert_eq!(number(object.0), u64::try_from(value).ok());
+        }
+        let fraction = 1.5_f64;
+        let object = Owned::new(CFNumberCreate(
+            std::ptr::null(),
+            6,
+            (&fraction as *const f64).cast(),
+        ))
+        .unwrap();
+        assert_eq!(number(object.0), None);
+    }
+}