3 files changed, 211 insertions, 0 deletions
diff --git a/xpcom/rust/gtest/xpcom/Cargo.toml b/xpcom/rust/gtest/xpcom/Cargo.toml
new file mode 100644
index 0000000000..777080b33b
--- /dev/null
+++ b/xpcom/rust/gtest/xpcom/Cargo.toml
@@ -0,0 +1,14 @@
+[package]
+name = "xpcom-gtest"
+version = "0.1.0"
+authors = ["michael@thelayzells.com"]
+license = "MPL-2.0"
+description = "Tests for rust bindings to xpcom interfaces"
+
+[dependencies]
+xpcom = { path = "../../xpcom" }
+nserror = { path = "../../nserror" }
+nsstring = { path = "../../nsstring" }
+
+[lib]
+path = "test.rs"
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
+}
diff --git a/xpcom/rust/gtest/xpcom/test.rs b/xpcom/rust/gtest/xpcom/test.rs
new file mode 100644
index 0000000000..f26a0140f3
--- /dev/null
+++ b/xpcom/rust/gtest/xpcom/test.rs
@@ -0,0 +1,131 @@
+/* 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/. */
+
+#![allow(non_snake_case)]
+
+#[macro_use]
+extern crate xpcom;
+
+extern crate nserror;
+
+use nserror::{nsresult, NS_OK};
+use std::ffi::{CStr, CString};
+use std::os::raw::c_char;
+use std::ptr;
+use xpcom::{interfaces, RefPtr};
+
+#[no_mangle]
+pub unsafe extern "C" fn Rust_ObserveFromRust() -> *const interfaces::nsIObserverService {
+    let obssvc: RefPtr<interfaces::nsIObserverService> =
+        xpcom::components::Observer::service().unwrap();
+
+    // Define an observer
+    #[xpcom(implement(nsIObserver), nonatomic)]
+    struct Observer {
+        run: *mut bool,
+    }
+    impl Observer {
+        unsafe fn Observe(
+            &self,
+            _subject: *const interfaces::nsISupports,
+            topic: *const c_char,
+            _data: *const u16,
+        ) -> nsresult {
+            *self.run = true;
+            assert!(CStr::from_ptr(topic).to_str() == Ok("test-rust-observe"));
+            NS_OK
+        }
+    }
+
+    let topic = CString::new("test-rust-observe").unwrap();
+
+    let mut run = false;
+    let observer = Observer::allocate(InitObserver { run: &mut run });
+    let rv = obssvc.AddObserver(
+        observer.coerce::<interfaces::nsIObserver>(),
+        topic.as_ptr(),
+        false,
+    );
+    assert!(rv.succeeded());
+
+    let rv = obssvc.NotifyObservers(ptr::null(), topic.as_ptr(), ptr::null());
+    assert!(rv.succeeded());
+    assert!(run, "The observer should have been run!");
+
+    let rv = obssvc.RemoveObserver(observer.coerce::<interfaces::nsIObserver>(), topic.as_ptr());
+    assert!(rv.succeeded());
+
+    assert!(
+        observer.coerce::<interfaces::nsISupports>() as *const _
+            == &*observer
+                .query_interface::<interfaces::nsISupports>()
+                .unwrap() as *const _
+    );
+
+    &*obssvc
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn Rust_ImplementRunnableInRust(
+    it_worked: *mut bool,
+    runnable: *mut *const interfaces::nsIRunnable,
+) {
+    // Define a type which implements nsIRunnable in rust.
+    #[xpcom(implement(nsIRunnable), atomic)]
+    struct RunnableFn<F: Fn() + 'static> {
+        run: F,
+    }
+
+    impl<F: Fn() + 'static> RunnableFn<F> {
+        unsafe fn Run(&self) -> nsresult {
+            (self.run)();
+            NS_OK
+        }
+    }
+
+    let my_runnable = RunnableFn::allocate(InitRunnableFn {
+        run: move || {
+            *it_worked = true;
+        },
+    });
+    my_runnable
+        .query_interface::<interfaces::nsIRunnable>()
+        .unwrap()
+        .forget(&mut *runnable);
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn Rust_GetMultipleInterfaces(
+    runnable: *mut *const interfaces::nsIRunnable,
+    observer: *mut *const interfaces::nsIObserver,
+) {
+    // Define a type which implements nsIRunnable and nsIObserver in rust, and
+    // hand both references back to c++
+    #[xpcom(implement(nsIRunnable, nsIObserver), atomic)]
+    struct MultipleInterfaces {}
+
+    impl MultipleInterfaces {
+        unsafe fn Run(&self) -> nsresult {
+            NS_OK
+        }
+        unsafe fn Observe(
+            &self,
+            _subject: *const interfaces::nsISupports,
+            _topic: *const c_char,
+            _data: *const u16,
+        ) -> nsresult {
+            NS_OK
+        }
+    }
+
+    let instance = MultipleInterfaces::allocate(InitMultipleInterfaces {});
+    instance
+        .query_interface::<interfaces::nsIRunnable>()
+        .unwrap()
+        .forget(&mut *runnable);
+    instance
+        .query_interface::<interfaces::nsIObserver>()
+        .unwrap()
+        .forget(&mut *observer);
+}