Better handle reentrancy into DocumentLoader::dataReceived().

Source/web/tests/DocumentLoaderTest.cpp

Index: Source/web/tests/DocumentLoaderTest.cpp
diff --git a/Source/web/tests/DocumentLoaderTest.cpp b/Source/web/tests/DocumentLoaderTest.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..71da5854b900e726c15a736f6b91b3e9f911fdf9
--- /dev/null
+++ b/Source/web/tests/DocumentLoaderTest.cpp
@@ -0,0 +1,169 @@
+// Copyright 2015 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 "platform/testing/URLTestHelpers.h"
+#include "public/platform/Platform.h"
+#include "public/platform/WebURLLoaderClient.h"
+#include "public/platform/WebUnitTestSupport.h"
+#include "web/WebLocalFrameImpl.h"
+#include "web/tests/FrameTestHelpers.h"
+#include "wtf/TemporaryChange.h"
+#include <gtest/gtest.h>
+#include <queue>
+#include <vector>
+
+namespace blink {
+
+class DocumentLoaderTest : public ::testing::Test {

[Nate Chapin, 2015/08/11 17:36:36]

It feels wrong to put this in web/ given the name.

[dcheng, 2015/08/11 17:41:37]

It does. The problem is:
- I can't put this test in core, since I need to use the machine in web/ for
loading.
- Naming the test something else seems weird, since this is trying to exercise
the new logic in DocumentLoader.

I'm open to any suggestions to make this situation less bad.

[Nate Chapin, 2015/08/12 21:10:53]

Ideally, we'd have enough of FrameTestHelpers in core that you could do this
without web. That's probably overkill for this patch.

A TODO/FIXME noting that this is a bad location should suffice.

[dcheng, 2015/08/12 22:06:40]

Done.

+protected:
+    void SetUp() override
+    {
+        m_webViewHelper.initialize();
+        URLTestHelpers::registerMockedURLLoad(URLTestHelpers::toKURL(
+            "https://example.com/foo.html"), "foo.html");
+    }
+
+    void TearDown() override
+    {
+        Platform::current()->unitTestSupport()->unregisterAllMockedURLs();
+    }
+
+    WebLocalFrameImpl* mainFrame()
+    {
+        return m_webViewHelper.webViewImpl()->mainFrameImpl();
+    }
+
+    FrameTestHelpers::WebViewHelper m_webViewHelper;
+};
+
+TEST_F(DocumentLoaderTest, SingleChunk)
+{
+    class TestDelegate : public WebURLLoaderTestDelegate {
+    public:
+        void didReceiveData(WebURLLoaderClient* originalClient, WebURLLoader* loader, const char* data, int dataLength, int encodedDataLength) override
+        {
+            EXPECT_EQ(34, dataLength) << "foo.html was not served in a single chunk";
+            originalClient->didReceiveData(loader, data, dataLength, encodedDataLength);
+        }
+    } delegate;

[Nate Chapin, 2015/08/11 17:36:36]

What does this syntax do? I'm not familiar with it.

[dcheng, 2015/08/11 17:41:37]

I just collapsed the definition of the class and the test delegate variable into
one statement.
If you think it'd be clearer, I can just put 'TestDelegate delegate'; on its own
line to avoid combining them like this.

+
+    Platform::current()->unitTestSupport()->setLoaderDelegate(&delegate);
+    FrameTestHelpers::loadFrame(mainFrame(), "https://example.com/foo.html");
+    Platform::current()->unitTestSupport()->setLoaderDelegate(nullptr);
+
+    // TODO(dcheng): How should the test verify that the original callback is
+    // invoked? The test currently still passes even if the test delegate
+    // forgets to invoke the callback.
+}
+
+// Test normal case of DocumentLoader::dataReceived(): data in multiple chunks,
+// with no reentrancy.
+TEST_F(DocumentLoaderTest, MultiChunkNoReentrancy)
+{
+    class TestDelegate : public WebURLLoaderTestDelegate {
+    public:
+        void didReceiveData(WebURLLoaderClient* originalClient, WebURLLoader* loader, const char* data, int dataLength, int encodedDataLength) override
+        {
+            EXPECT_EQ(34, dataLength) << "foo.html was not served in a single chunk";
+            // Chunk the reply into one byte chunks.
+            for (int i = 0; i < dataLength; ++i)
+                originalClient->didReceiveData(loader, &data[i], 1, 1);
+        }
+    } delegate;
+
+    Platform::current()->unitTestSupport()->setLoaderDelegate(&delegate);
+    FrameTestHelpers::loadFrame(mainFrame(), "https://example.com/foo.html");
+    Platform::current()->unitTestSupport()->setLoaderDelegate(nullptr);
+}
+
+// Finally, test reentrant callbacks to DocumentLoader::dataReceived().
+TEST_F(DocumentLoaderTest, MultiChunkWithReentrancy)
+{
+    // This test delegate chunks the response stage into three distinct stages:
+    // 1. The first dataReceived() callback, which triggers frame detach due to
+    //    commiting a provisional load.
+    // 2.  The middle part of the response, which is dispatched to
+    //    dataReceived() reentrantly.
+    // 3. The final chunk, which is dispatched normally at the top-level.
+    class TestDelegate
+        : public WebURLLoaderTestDelegate, public FrameTestHelpers::TestWebFrameClient {
+    public:
+        TestDelegate() : m_loaderClient(nullptr), m_loader(nullptr), m_dispatchingDidReceiveData(false), m_servedReentrantly(false) { }
+
+        // WebURLLoaderTestDelegate overrides:
+        void didReceiveData(WebURLLoaderClient* originalClient, WebURLLoader* loader, const char* data, int dataLength, int encodedDataLength) override
+        {
+            EXPECT_EQ(34, dataLength) << "foo.html was not served in a single chunk";
+
+            m_loaderClient = originalClient;
+            m_loader = loader;
+            for (int i = 0; i < dataLength; ++i)
+                m_data.push(data[i]);
+
+            {
+                // Serve the first byte to the real WebURLLoaderCLient, which
+                // should trigger frameDetach() due to committing a provisional
+                // load.
+                TemporaryChange<bool> dispatching(m_dispatchingDidReceiveData, true);
+                dispatchOneByte();
+            }
+            // Serve the remaining bytes to complete the load.
+            EXPECT_FALSE(m_data.empty());
+            while (!m_data.empty())
+                dispatchOneByte();
+        }
+
+        // WebFrameClient overrides:
+        void frameDetached(WebFrame* frame, DetachType detachType) override
+        {
+            if (m_dispatchingDidReceiveData) {
+                // This should be called by the first didReceiveData() call, since
+                // it should commit the provisional load.
+                EXPECT_GT(m_data.size(), 10u);
+                // Dispatch dataReceived() callbacks for part of the remaining
+                // data, saving the rest to be dispatched at the top-level as
+                // normal.
+                while (m_data.size() > 10)
+                    dispatchOneByte();
+                m_servedReentrantly = true;
+            }
+            TestWebFrameClient::frameDetached(frame, detachType);
+        }
+
+        void dispatchOneByte()
+        {
+            char c = m_data.front();
+            m_data.pop();
+            m_loaderClient->didReceiveData(m_loader, &c, 1, 1);
+        }
+
+        bool servedReentrantly() const { return m_servedReentrantly; }
+
+    private:
+        WebURLLoaderClient* m_loaderClient;
+        WebURLLoader* m_loader;
+        std::queue<char> m_data;
+        bool m_dispatchingDidReceiveData;
+        bool m_servedReentrantly;
+    } delegate;
+    m_webViewHelper.initialize(false, &delegate);
+
+    // This doesn't go through the mocked URL load path: it's just intended to
+    // setup a situation where didReceiveData() can be invoked reentrantly.
+    FrameTestHelpers::loadHTMLString(mainFrame(), "<iframe></iframe>", URLTestHelpers::toKURL("about:blank"));
+
+    Platform::current()->unitTestSupport()->setLoaderDelegate(&delegate);
+    FrameTestHelpers::loadFrame(mainFrame(), "https://example.com/foo.html");
+    Platform::current()->unitTestSupport()->setLoaderDelegate(nullptr);
+
+    EXPECT_TRUE(delegate.servedReentrantly());
+
+    // delegate is a WebFrameClient and stack-allocated, so manually reset() the
+    // WebViewHelper here.
+    m_webViewHelper.reset();
+}
+
+} // namespace blink