1 files changed, 57 insertions, 0 deletions
diff --git a/toolkit/components/uniffi-bindgen-gecko-js/fixtures/tests/xpcshell/test_refcounts.js b/toolkit/components/uniffi-bindgen-gecko-js/fixtures/tests/xpcshell/test_refcounts.js
new file mode 100644
index 0000000000..790d981104
--- /dev/null
+++ b/toolkit/components/uniffi-bindgen-gecko-js/fixtures/tests/xpcshell/test_refcounts.js
@@ -0,0 +1,57 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+const { getSingleton, getJsRefcount } = ChromeUtils.importESModule(
+  "resource://gre/modules/RustRefcounts.sys.mjs"
+);
+
+// Test refcounts when we call methods.
+//
+// Each method call requires that we clone the Arc pointer on the JS side, then pass it to Rust
+// which will consumer the reference.  Make sure we get this right
+
+function createObjectAndCallMethods() {
+  const obj = getSingleton();
+  obj.method();
+}
+
+add_test(() => {
+  // Create an object that we'll keep around.  If the ref count ends up being low, we don't want
+  // to reduce it below 0, since the Rust code may catch that and clamp it
+  const obj = getSingleton();
+  createObjectAndCallMethods();
+  Cu.forceGC();
+  Cu.forceCC();
+  do_test_pending();
+  do_timeout(500, () => {
+    Assert.equal(getJsRefcount(), 1);
+    // Use `obj` to avoid unused warnings and try to ensure that JS doesn't destroy it early
+    obj.method();
+    do_test_finished();
+    run_next_test();
+  });
+});
+
+// Test refcounts when creating/destroying objects
+function createAndDeleteObjects() {
+  [getSingleton(), getSingleton(), getSingleton()];
+}
+
+add_test(() => {
+  const obj = getSingleton();
+  createAndDeleteObjects();
+  Cu.forceGC();
+  Cu.forceCC();
+  do_timeout(500, () => {
+    Assert.equal(getJsRefcount(), 1);
+    obj.method();
+    do_test_finished();
+    run_next_test();
+  });
+});
+
+// As we implement more UniFFI features we should probably add refcount tests for it.
+// Some features that should probably have tests:
+//   - Async methods
+//   - UniFFI builtin trait methods like 'to_string'
+//   - Rust trait objects