test: add memory leak test (#726)

Author: Boshen

src/tests/memory_leak.rs

@@ -0,0 +1,24 @@
+use std::sync::Arc;
+
+use crate::Resolver;
+
+/// Test to prove memory leak in `CachedPath` Arc cycles
+#[test]
+fn test_memory_leak_arc_cycles() {
+    let f = super::fixture_root().join("misc");
+
+    let resolver = Resolver::default();
+
+    let path = resolver.cache.value(&f);
+
+    resolver.resolve(&f, "package-json-nested").unwrap();
+
+    // Populated cache - path is now owned in multiple places.
+    assert_eq!(Arc::strong_count(&path.0), 4);
+
+    // Drop the resolver.
+    drop(resolver);
+
+    // All Arcs must be dropped, leaving the original count of 1.
+    assert_eq!(Arc::strong_count(&path.0), 1);
+}

src/tests/mod.rs

@@ -11,6 +11,7 @@ mod imports_field;
 mod incorrect_description_file;
 mod main_field;
 mod memory_fs;
+mod memory_leak;
 mod missing;
 mod module_type;
 mod package_json;