1 files changed, 91 insertions, 0 deletions
diff --git a/xpcom/tests/gtest/TestEventPriorities.cpp b/xpcom/tests/gtest/TestEventPriorities.cpp
new file mode 100644
index 0000000000..874fc81a33
--- /dev/null
+++ b/xpcom/tests/gtest/TestEventPriorities.cpp
@@ -0,0 +1,91 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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 "nsCOMPtr.h"
+#include "nsIRunnable.h"
+#include "nsXPCOM.h"
+#include "nsThreadUtils.h"
+#include "gtest/gtest.h"
+#include "mozilla/SpinEventLoopUntil.h"
+
+#include <functional>
+
+using namespace mozilla;
+
+class TestEvent final : public Runnable, nsIRunnablePriority {
+ public:
+  explicit TestEvent(int* aCounter, std::function<void()>&& aCheck,
+                     uint32_t aPriority = nsIRunnablePriority::PRIORITY_NORMAL)
+      : Runnable("TestEvent"),
+        mCounter(aCounter),
+        mCheck(std::move(aCheck)),
+        mPriority(aPriority) {}
+
+  NS_DECL_ISUPPORTS_INHERITED
+
+  NS_IMETHOD GetPriority(uint32_t* aPriority) override {
+    *aPriority = mPriority;
+    return NS_OK;
+  }
+
+  NS_IMETHODIMP Run() override {
+    (*mCounter)++;
+    mCheck();
+    return NS_OK;
+  }
+
+ private:
+  ~TestEvent() = default;
+
+  int* mCounter;
+  std::function<void()> mCheck;
+  uint32_t mPriority;
+};
+
+NS_IMPL_ISUPPORTS_INHERITED(TestEvent, Runnable, nsIRunnablePriority)
+
+TEST(EventPriorities, IdleAfterNormal)
+{
+  int normalRan = 0, idleRan = 0;
+
+  RefPtr<TestEvent> evNormal =
+      new TestEvent(&normalRan, [&] { ASSERT_EQ(idleRan, 0); });
+  RefPtr<TestEvent> evIdle =
+      new TestEvent(&idleRan, [&] { ASSERT_EQ(normalRan, 3); });
+
+  NS_DispatchToCurrentThreadQueue(do_AddRef(evIdle), EventQueuePriority::Idle);
+  NS_DispatchToCurrentThreadQueue(do_AddRef(evIdle), EventQueuePriority::Idle);
+  NS_DispatchToCurrentThreadQueue(do_AddRef(evIdle), EventQueuePriority::Idle);
+  NS_DispatchToMainThread(evNormal);
+  NS_DispatchToMainThread(evNormal);
+  NS_DispatchToMainThread(evNormal);
+
+  MOZ_ALWAYS_TRUE(
+      SpinEventLoopUntil("xpcom:TEST(EventPriorities, IdleAfterNormal)"_ns,
+                         [&]() { return normalRan == 3 && idleRan == 3; }));
+}
+
+TEST(EventPriorities, HighNormal)
+{
+  int normalRan = 0, highRan = 0;
+
+  RefPtr<TestEvent> evNormal = new TestEvent(
+      &normalRan, [&] { ASSERT_TRUE((highRan - normalRan) >= 0); });
+  RefPtr<TestEvent> evHigh = new TestEvent(
+      &highRan, [&] { ASSERT_TRUE((highRan - normalRan) >= 0); },
+      nsIRunnablePriority::PRIORITY_VSYNC);
+
+  NS_DispatchToMainThread(evNormal);
+  NS_DispatchToMainThread(evNormal);
+  NS_DispatchToMainThread(evNormal);
+  NS_DispatchToMainThread(evHigh);
+  NS_DispatchToMainThread(evHigh);
+  NS_DispatchToMainThread(evHigh);
+
+  MOZ_ALWAYS_TRUE(
+      SpinEventLoopUntil("xpcom:TEST(EventPriorities, HighNormal)"_ns,
+                         [&]() { return normalRan == 3 && highRan == 3; }));
+}