1 files changed, 66 insertions, 0 deletions
diff --git a/xpcom/rust/gtest/xpcom/TestXpcom.cpp b/xpcom/rust/gtest/xpcom/TestXpcom.cpp
new file mode 100644
index 0000000000..69425274f6
--- /dev/null
+++ b/xpcom/rust/gtest/xpcom/TestXpcom.cpp
@@ -0,0 +1,66 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "gtest/gtest.h"
+#include "nsCOMPtr.h"
+#include "nsIRunnable.h"
+#include "nsIObserver.h"
+#include "mozilla/Services.h"
+#include "nsIObserverService.h"
+
+extern "C" nsIObserverService* Rust_ObserveFromRust();
+
+TEST(RustXpcom, ObserverFromRust)
+{
+  nsCOMPtr<nsIObserverService> rust = Rust_ObserveFromRust();
+  nsCOMPtr<nsIObserverService> cpp = mozilla::services::GetObserverService();
+  EXPECT_EQ(rust, cpp);
+}
+
+extern "C" void Rust_ImplementRunnableInRust(bool* aItWorked,
+                                             nsIRunnable** aRunnable);
+
+TEST(RustXpcom, ImplementRunnableInRust)
+{
+  bool itWorked = false;
+  nsCOMPtr<nsIRunnable> runnable;
+  Rust_ImplementRunnableInRust(&itWorked, getter_AddRefs(runnable));
+
+  EXPECT_TRUE(runnable);
+  EXPECT_FALSE(itWorked);
+  runnable->Run();
+  EXPECT_TRUE(itWorked);
+}
+
+extern "C" void Rust_GetMultipleInterfaces(nsIRunnable** aRunnable,
+                                           nsIObserver** aObserver);
+
+TEST(RustXpcom, DynamicCastVoid)
+{
+  nsCOMPtr<nsIRunnable> runnable;
+  nsCOMPtr<nsIObserver> observer;
+  Rust_GetMultipleInterfaces(getter_AddRefs(runnable),
+                             getter_AddRefs(observer));
+
+  // They should have different addresses when `static_cast` to void*
+  EXPECT_NE(static_cast<void*>(runnable.get()),
+            static_cast<void*>(observer.get()));
+
+  // These should be the same object
+  nsCOMPtr<nsISupports> runnableSupports = do_QueryInterface(runnable);
+  nsCOMPtr<nsISupports> observerSupports = do_QueryInterface(observer);
+  EXPECT_EQ(runnableSupports.get(), observerSupports.get());
+
+#ifndef XP_WIN
+  // They should have the same address when dynamic_cast to void*
+  // dynamic_cast<void*> is not supported without rtti on windows.
+  EXPECT_EQ(dynamic_cast<void*>(runnable.get()),
+            dynamic_cast<void*>(observer.get()));
+
+  // The nsISupports pointer from `do_QueryInterface` should match
+  // `dynamic_cast<void*>`
+  EXPECT_EQ(dynamic_cast<void*>(observer.get()),
+            static_cast<void*>(observerSupports.get()));
+#endif
+}