Support "await a stable state" and "provide a stable state"

Source/core/html/StableStateTest.cpp

Index: Source/core/html/StableStateTest.cpp
diff --git a/Source/core/html/StableStateTest.cpp b/Source/core/html/StableStateTest.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..21a7c070657f6ac017de953bbce76da9820130ca
--- /dev/null
+++ b/Source/core/html/StableStateTest.cpp
@@ -0,0 +1,108 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "config.h"
+#include "core/html/StableState.h"
+
+#include "wtf/Functional.h"
+
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+
+using WebCore::StableState;
+
+namespace {
+
+class MockAwaiter : public StableState::Awaiter {
+public:
+    MOCK_METHOD0(didAwaitStableState, void());
+};
+
+TEST(StableState, Await)
+{
+    MockAwaiter awaiter;
+    EXPECT_CALL(awaiter, didAwaitStableState()).Times(0);
+    StableState::await(awaiter);
+}
+
+TEST(StableState, AwaitProvide)
+{
+    MockAwaiter awaiter;
+    EXPECT_CALL(awaiter, didAwaitStableState()).Times(1);
+    StableState::await(awaiter);
+    StableState::provide();
+}
+
+TEST(StableState, AwaitProvideTwice)
+{
+    MockAwaiter awaiter;
+    EXPECT_CALL(awaiter, didAwaitStableState()).Times(1);
+    StableState::await(awaiter);
+    StableState::provide();
+    StableState::provide();
+}
+
+TEST(StableState, AwaitTwiceProvide)
+{
+    MockAwaiter awaiter;
+    EXPECT_CALL(awaiter, didAwaitStableState()).Times(1);
+    StableState::await(awaiter);
+    StableState::await(awaiter);
+    StableState::provide();
+}
+
+TEST(StableState, AwaitProvideAwaitProvide)
+{
+    MockAwaiter awaiter;
+    EXPECT_CALL(awaiter, didAwaitStableState()).Times(2);
+    StableState::await(awaiter);
+    StableState::provide();
+    StableState::await(awaiter);
+    StableState::provide();
+}
+
+TEST(StableState, TwoAwaiters)
+{
+    MockAwaiter awaiter1;
+    MockAwaiter awaiter2;
+    EXPECT_CALL(awaiter1, didAwaitStableState()).Times(1);
+    EXPECT_CALL(awaiter2, didAwaitStableState()).Times(1);
+    StableState::await(awaiter1);
+    StableState::await(awaiter2);
+    StableState::provide();
+}
+
+// Test that a class can await a stable state and invoke one of two callbacks
+// without inheriting StableState::Awaiter or having state bits.
+
+class MockCallbacks {
+public:
+    MOCK_METHOD0(callback1, void());
+    MOCK_METHOD0(callback2, void());
+};
+
+class ClosureAwaiter : public StableState::Awaiter {
+public:
+    ClosureAwaiter(const Closure& closure) : m_closure(closure) { }
+    virtual void didAwaitStableState() OVERRIDE
+    {
+        m_closure();
+        delete this;
+    }
+private:
+    Closure m_closure;
+};
+
+TEST(StableState, ClosureAwaiter)
+{
+    MockCallbacks callbacks;
+    EXPECT_CALL(callbacks, callback1()).Times(2);
+    EXPECT_CALL(callbacks, callback2()).Times(1);
+    StableState::await(*new ClosureAwaiter(bind(&MockCallbacks::callback1, &callbacks)));

[acolwell GONE FROM CHROMIUM, 2014/02/07 19:09:31]

I don't quite get what this is testing. Why do you need the new/delete business
here? Can't you just use local variables like you do in the tests above?

[philipj_slow, 2014/02/09 17:10:17]

This is verifying the "separate StableState::Awaiter subclass" use case
mentioned in the commit message. I've expanded on the comment above to clarify.
It's easy to screw up delete during iteration, for example if one uses a
Vector<StableState::Awaiter*> and StableState::provide() iterates it directly
(no swap), all previous tests pass but this one crashes.

+    StableState::await(*new ClosureAwaiter(bind(&MockCallbacks::callback2, &callbacks)));
+    StableState::await(*new ClosureAwaiter(bind(&MockCallbacks::callback1, &callbacks)));
+    StableState::provide();
+}
+
+} // namespace