Refactor PipelineImpl to use CompositeFilter to manage Filter state transitions.

media/base/composite_filter_unittest.cc

Index: media/base/composite_filter_unittest.cc
diff --git a/media/base/composite_filter_unittest.cc b/media/base/composite_filter_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..7e5e0546a182c59806d884317c9aff47997e47af
--- /dev/null
+++ b/media/base/composite_filter_unittest.cc
@@ -0,0 +1,845 @@
+// Copyright (c) 2010 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 "media/base/composite_filter.h"
+#include "media/base/mock_filter_host.h"
+#include "media/base/mock_filters.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+using ::testing::_;
+using ::testing::InSequence;
+using ::testing::Return;
+using ::testing::SaveArg;
+using ::testing::StrictMock;
+
+namespace media {
+
+class CompositeFilterTest : public testing::Test {
+ public:
+  CompositeFilterTest();
+  virtual ~CompositeFilterTest();
+
+  // Sets up a new CompositeFilter in |composite_|, creates |filter_1_| and
+  // |filter_2_|, and adds these filters to |composite_|.
+  void SetupAndAdd2Filters();
+
+  // Helper enum that indicates what filter method to call.
+  enum MethodToCall {
+    PLAY,
+    PAUSE,
+    FLUSH,
+    STOP,
+    SEEK,
+  };
+
+  // Helper method that adds a filter method call expectation based on the value
+  // of |method_to_call|.
+  //
+  // |method_to_call| - Indicates which method we expect a call for.
+  // |filter| - The MockFilter to add the expectation to.
+  // |seek_time| - The time to pass to the Seek() call if |method_to_call|
+  //               equals SEEK.
+  void ExpectFilterCall(MethodToCall method_to_call, MockFilter* filter,
+                        base::TimeDelta seek_time);
+
+  // Helper method that calls a filter method based on the value of
+  // |method_to_call|.
+  //
+  // |method_to_call| - Indicates which method to call.
+  // |filter| - The Filter to make the method call on.
+  // |seek_time| - The time to pass to the Seek() call if |method_to_call|
+  //               equals SEEK.
+  // |callback| - The callback object to pass to the method.
+  void DoFilterCall(MethodToCall method_to_call, Filter* filter,
+                    base::TimeDelta seek_time,
+                    FilterCallback* callback);
+
+  // Creates an expectation sequence based on the value of method_to_call.
+  //
+  // |method_to_call| - Indicates which method we want a success sequence for.
+  // |seek_time| - The time to pass in the Seek() call if |method_to_call|
+  //               equals SEEK.
+  void ExpectSuccess(MethodToCall method_to_call,
+                     base::TimeDelta seek_time = base::TimeDelta());
+
+  // Issue a Play(), Pause(), Flush(), Stop(), or Seek() on the composite and
+  // verify all the expected calls on the filters.
+  void DoPlay();
+  void DoPause();
+  void DoFlush();
+  void DoStop();
+  void DoSeek(base::TimeDelta time);
+
+  // Issue a Play(), Pause(), Flush(), or Seek() and expect the calls to fail
+  // with a PIPELINE_ERROR_INVALID_STATE error.
+  //
+  // |method_to_call| - Indicates whick method to call.
+  // |seek_time| - The time to pass to the Seek() call if |method_to_call|
+  //               equals SEEK.
+  void ExpectInvalidStateFail(MethodToCall method_to_call,
+                  base::TimeDelta seek_time = base::TimeDelta());
+
+  // Run the callback stored in |filter_1_callback_|,

[scherkus (not reviewing), 2010/12/16 18:43:39]

nit: , -> .

[acolwell GONE FROM CHROMIUM, 2010/12/20 17:43:22]

Done.

+  void RunFilter1Callback();
+
+  // Run the callback stored in |filter_2_callback_|,

[scherkus (not reviewing), 2010/12/16 18:43:39]

nit: , -> .

[acolwell GONE FROM CHROMIUM, 2010/12/20 17:43:22]

Done.

+  void RunFilter2Callback();
+
+ protected:
+  MessageLoop message_loop_;
+
+  // The composite object being tested.
+  scoped_refptr<CompositeFilter> composite_;
+
+  // First filter added to the composite.
+  scoped_refptr<StrictMock<MockFilter> > filter_1_;
+
+  // Callback passed to |filter_1_| during last Play(), Pause(), Flush(),
+  // Stop(), or Seek() call.
+  FilterCallback* filter_1_callback_;
+
+  // Second filter added to the composite.
+  scoped_refptr<StrictMock<MockFilter> > filter_2_;
+
+  // Callback passed to |filter_2_| during last Play(), Pause(), Flush(),
+  // Stop(), or Seek() call.
+  FilterCallback* filter_2_callback_;
+
+  // FilterHost implementation passed to |composite_| via set_host().
+  scoped_ptr<StrictMock<MockFilterHost> > mock_filter_host_;
+
+  DISALLOW_COPY_AND_ASSIGN(CompositeFilterTest);
+};
+
+CompositeFilterTest::CompositeFilterTest() :
+    composite_(new CompositeFilter(&message_loop_)),
+    filter_1_callback_(NULL),
+    filter_2_callback_(NULL),
+    mock_filter_host_(new StrictMock<MockFilterHost>()){

[scherkus (not reviewing), 2010/12/16 18:43:39]

nit: space between ) and {

[acolwell GONE FROM CHROMIUM, 2010/12/20 17:43:22]

Done.

+}
+
+CompositeFilterTest::~CompositeFilterTest() {}
+
+void CompositeFilterTest::SetupAndAdd2Filters() {
+  mock_filter_host_.reset(new StrictMock<MockFilterHost>());
+  composite_ = new CompositeFilter(&message_loop_);
+  composite_->set_host(mock_filter_host_.get());
+
+  // Setup |filter_1_| and arrange for methods to set
+  // |filter_1_callback_| when they are called.
+  filter_1_ = new StrictMock<MockFilter>();
+  filter_1_callback_ = NULL;
+  ON_CALL(*filter_1_, Play(_))
+      .WillByDefault(SaveArg<0>(&filter_1_callback_));
+  ON_CALL(*filter_1_, Pause(_))
+      .WillByDefault(SaveArg<0>(&filter_1_callback_));
+  ON_CALL(*filter_1_, Flush(_))
+      .WillByDefault(SaveArg<0>(&filter_1_callback_));
+  ON_CALL(*filter_1_, Stop(_))
+      .WillByDefault(SaveArg<0>(&filter_1_callback_));
+  ON_CALL(*filter_1_, Seek(_,_))
+      .WillByDefault(SaveArg<1>(&filter_1_callback_));
+
+  // Setup |filter_2_| and arrange for methods to set
+  // |filter_2_callback_| when they are called.
+  filter_2_ = new StrictMock<MockFilter>();
+  filter_2_callback_ = NULL;
+  ON_CALL(*filter_2_, Play(_))
+      .WillByDefault(SaveArg<0>(&filter_2_callback_));
+  ON_CALL(*filter_2_, Pause(_))
+      .WillByDefault(SaveArg<0>(&filter_2_callback_));
+  ON_CALL(*filter_2_, Flush(_))
+      .WillByDefault(SaveArg<0>(&filter_2_callback_));
+  ON_CALL(*filter_2_, Stop(_))
+      .WillByDefault(SaveArg<0>(&filter_2_callback_));
+  ON_CALL(*filter_2_, Seek(_,_))
+      .WillByDefault(SaveArg<1>(&filter_2_callback_));
+
+  composite_->AddFilter(filter_1_);
+  composite_->AddFilter(filter_2_);
+}
+
+void CompositeFilterTest::ExpectFilterCall(MethodToCall method_to_call,
+                                           MockFilter* filter,
+                                           base::TimeDelta seek_time) {
+  switch(method_to_call) {
+    case PLAY:
+      EXPECT_CALL(*filter, Play(_));
+      break;
+    case PAUSE:
+      EXPECT_CALL(*filter, Pause(_));
+      break;
+    case FLUSH:
+      EXPECT_CALL(*filter, Flush(_));
+      break;
+    case STOP:
+      EXPECT_CALL(*filter, Stop(_));
+      break;
+    case SEEK:
+      EXPECT_CALL(*filter, Seek(seek_time, _));
+      break;
+  };
+}
+
+void CompositeFilterTest::DoFilterCall(MethodToCall method_to_call,
+                                       Filter* filter,
+                                       base::TimeDelta seek_time,
+                                       FilterCallback* callback) {
+  switch(method_to_call) {
+    case PLAY:
+      filter->Play(callback);
+      break;
+    case PAUSE:
+      filter->Pause(callback);
+      break;
+    case FLUSH:
+      filter->Flush(callback);
+      break;
+    case STOP:
+      filter->Stop(callback);
+      break;
+    case SEEK:
+      filter->Seek(seek_time, callback);
+      break;
+  };
+}
+
+void CompositeFilterTest::ExpectSuccess(MethodToCall method_to_call,
+                                        base::TimeDelta seek_time) {
+  InSequence seq;
+
+  scoped_ptr<StrictMock<MockFilterCallback> > mock_callback(
+      new StrictMock<MockFilterCallback>(false));
+
+  bool is_parallel_call = (method_to_call == FLUSH);
+
+  ExpectFilterCall(method_to_call, filter_1_.get(), seek_time);
+
+  if (is_parallel_call) {
+    ExpectFilterCall(method_to_call, filter_2_.get(), seek_time);
+  }
+
+  // Make method call on the composite.
+  DoFilterCall(method_to_call, composite_.get(), seek_time,
+               mock_callback->NewCallback());
+
+  if (is_parallel_call) {
+    // Make sure both filters have their callbacks set.
+    EXPECT_NE((FilterCallback*)NULL, filter_1_callback_);

[scherkus (not reviewing), 2010/12/16 18:43:39]

ok I debugged this a bit because that's strange...

turns out EXPECT_EQ, EXPECT_TRUE, and EXPECT_FALSE all work but it's only
EXPECT_NE that complains

you can either go around and static_cast<> everything but I think it'd be easier
to do EXPECT_TRUE/EXPECT_FALSE for pointer checks

caveat: I only tested this on linux so if it's win/mac that's complaining we
might have to static_cast<> it up :(

[acolwell GONE FROM CHROMIUM, 2010/12/20 17:43:22]

Done. I just changed the EXPECT_NE()s to EXPECT_TRUE()

+    EXPECT_NE((FilterCallback*)NULL, filter_2_callback_);
+
+    RunFilter1Callback();
+  } else {
+    // Make sure that only |filter_1_| has its callback set.
+    EXPECT_NE((FilterCallback*)NULL, filter_1_callback_);
+    EXPECT_EQ((FilterCallback*)NULL, filter_2_callback_);
+
+    ExpectFilterCall(method_to_call, filter_2_.get(), seek_time);
+
+    RunFilter1Callback();
+
+    // Verify that |filter_2_| was called by checking the callback pointer.
+    EXPECT_NE((FilterCallback*)NULL, filter_2_callback_);
+  }
+
+  EXPECT_CALL(*mock_callback, OnFilterCallback());
+
+  RunFilter2Callback();
+}
+
+void CompositeFilterTest::DoPlay() {
+  ExpectSuccess(PLAY);
+}
+
+void CompositeFilterTest::DoPause() {
+  ExpectSuccess(PAUSE);
+}
+
+void CompositeFilterTest::DoFlush() {
+  ExpectSuccess(FLUSH);
+}
+
+void CompositeFilterTest::DoStop() {
+  ExpectSuccess(STOP);
+}
+
+void CompositeFilterTest::DoSeek(base::TimeDelta time) {
+  ExpectSuccess(SEEK, time);
+}
+
+void CompositeFilterTest::ExpectInvalidStateFail(MethodToCall method_to_call,
+                                     base::TimeDelta seek_time) {
+  InSequence seq;
+  scoped_ptr<StrictMock<MockFilterCallback> > mock_callback(
+      new StrictMock<MockFilterCallback>(false));
+
+  EXPECT_CALL(*mock_filter_host_, SetError(PIPELINE_ERROR_INVALID_STATE))
+      .WillOnce(Return());
+  EXPECT_CALL(*mock_callback, OnFilterCallback());
+
+  DoFilterCall(method_to_call, composite_, seek_time,
+               mock_callback->NewCallback());
+
+  // Make sure that neither of the filters were called by
+  // verifying that the callback pointers weren't set.
+  EXPECT_EQ((FilterCallback*)NULL, filter_1_callback_);
+  EXPECT_EQ((FilterCallback*)NULL, filter_2_callback_);
+}
+
+void CompositeFilterTest::RunFilter1Callback() {
+  EXPECT_NE((FilterCallback*)NULL, filter_1_callback_);
+  FilterCallback* callback = filter_1_callback_;
+  filter_1_callback_ = NULL;
+  callback->Run();
+  delete callback;
+}
+
+void CompositeFilterTest::RunFilter2Callback() {
+  EXPECT_NE((FilterCallback*)NULL, filter_2_callback_);
+  FilterCallback* callback = filter_2_callback_;
+  filter_2_callback_ = NULL;
+  callback->Run();
+  delete callback;
+}
+
+static base::Thread* NullThreadFactory(const char* thread_name) {
+  return NULL;
+}
+
+// Test AddFilter() failure cases.
+TEST_F(CompositeFilterTest, TestAddFilterFailCases) {
+  // Test adding a null pointer.
+  EXPECT_FALSE(composite_->AddFilter(NULL));
+
+  scoped_refptr<StrictMock<MockFilter> > filter =
+      new StrictMock<MockFilter>(true);
+  EXPECT_EQ(NULL, filter->host());
+  EXPECT_EQ(NULL, filter->message_loop());
+
+  // Test failing because set_host() hasn't been called yet.
+  EXPECT_FALSE(composite_->AddFilter(filter));
+
+  // Test thread creation failure.
+  composite_ = new CompositeFilter(&message_loop_, &NullThreadFactory);
+  composite_->set_host(mock_filter_host_.get());
+  EXPECT_FALSE(composite_->AddFilter(filter));
+  EXPECT_EQ(NULL, filter->host());
+  EXPECT_EQ(NULL, filter->message_loop());
+}
+
+// Test successful AddFilter() cases.
+TEST_F(CompositeFilterTest, TestAddFilter) {
+  composite_->set_host(mock_filter_host_.get());
+
+  // Add a filter that doesn't require a message loop.
+  scoped_refptr<StrictMock<MockFilter> > filter = new StrictMock<MockFilter>();
+  EXPECT_EQ(NULL, filter->host());
+  EXPECT_EQ(NULL, filter->message_loop());
+
+  EXPECT_TRUE(composite_->AddFilter(filter));
+
+  EXPECT_NE((FilterHost*)NULL, filter->host());
+  EXPECT_EQ(NULL, filter->message_loop());
+
+  // Add a filter that requires a message loop.
+  scoped_refptr<StrictMock<MockFilter> > filter_2 =
+      new StrictMock<MockFilter>(true);
+
+  EXPECT_EQ(NULL, filter_2->host());
+  EXPECT_EQ(NULL, filter_2->message_loop());
+
+  EXPECT_TRUE(composite_->AddFilter(filter_2));
+
+  EXPECT_NE((FilterHost*)NULL, filter_2->host());
+  EXPECT_NE((MessageLoop*)NULL, filter_2->message_loop());
+}
+
+static bool g_thread_cleanup_called_ = false;
+class CompositeFilterThread : public base::Thread {
+ public:
+  CompositeFilterThread(const char* name) : base::Thread(name) {}
+  virtual void CleanUp() {
+    g_thread_cleanup_called_ = true;
+    base::Thread::CleanUp();
+  }
+};
+
+static base::Thread* g_thread_created_by_factory = NULL;
+static base::Thread* TestableThreadFactory(const char* thread_name) {
+  g_thread_created_by_factory = new CompositeFilterThread(thread_name);
+  return g_thread_created_by_factory;
+}
+
+// Verify that thread termination works as expected.
+TEST_F(CompositeFilterTest, TestThreadTermination) {

[scherkus (not reviewing), 2010/12/16 18:43:39]

I still don't think we need (most of) this test since a good chunk seems to
verify Thread and not CompositeFilter

the real core of the test is to see if some thread was created and that it was
assigned to a filter, which can be accomplished with a much smaller test:

EXEPECT_FALSE(MessageLoop::current());  // make sure this thread has no message
loop
EXPECT_TRUE(filter->message_loop());  // make sure filter has some sort of
message loop

Now that I think about it I'm also wondering whether it's CompositeFilter's
responsibility to create + inject threads... does it make sense for it to be
accomplished at the AddFilter() level?  For example:
AddFilter(Filter*, MessageLoop*)
AddFilter(Filter*, Thread*)

Basically it's another red-flag of mine when I see unit tests that aren't
capable of running on a single thread (i.e., threads are getting
created/deleted), so just doing some sanity checking.

It might be required in a follow change if/when we get rid of
requires_message_loop() (I don't think Filters should be responsible for
determining whether they get a thread or not, but rather the application i.e.,
Pipeline)

[acolwell GONE FROM CHROMIUM, 2010/12/20 17:43:22]

Removed the test case.
Agree that thread management needs to be changed, but will do so in a separate
CL.

+  composite_ = new CompositeFilter(&message_loop_, &TestableThreadFactory);
+  composite_->set_host(mock_filter_host_.get());
+
+  // Add a filter that requires a message loop.
+  scoped_refptr<StrictMock<MockFilter> > filter =
+      new StrictMock<MockFilter>(true);
+
+  EXPECT_EQ(NULL, g_thread_created_by_factory);
+  EXPECT_TRUE(composite_->AddFilter(filter));
+  EXPECT_NE((base::Thread*)NULL, g_thread_created_by_factory);
+  EXPECT_NE((MessageLoop*)NULL, filter->message_loop());
+
+  // Verify that the filter has a message loop and it matches the
+  // thread's message loop.
+  base::Thread* filter_thread = g_thread_created_by_factory;
+  EXPECT_NE((MessageLoop*)NULL, filter_thread->message_loop());
+  EXPECT_EQ(filter_thread->message_loop(), filter->message_loop());
+
+  EXPECT_TRUE(filter_thread->IsRunning());
+  EXPECT_FALSE(g_thread_cleanup_called_);
+
+  composite_ = NULL;
+
+  // Verify that the thread stops running when the composite is
+  // destroyed.
+  EXPECT_TRUE(g_thread_cleanup_called_);
+}
+
+TEST_F(CompositeFilterTest, TestPlay) {
+  InSequence sequence;
+
+  SetupAndAdd2Filters();
+
+  // Verify successful call to Play().
+  DoPlay();
+
+  // At this point we are now in the kPlaying state.
+  scoped_ptr<StrictMock<MockFilterCallback> > mock_callback(
+      new StrictMock<MockFilterCallback>(false));
+
+  // Try calling Play() again to make sure that we simply get a callback.
+  // We are already in the Play() state so there is no point calling the
+  // filters.
+  EXPECT_CALL(*mock_callback, OnFilterCallback());
+
+  composite_->Play(mock_callback->NewCallback());
+
+  // Verify that neither of the filter callbacks were set.
+  EXPECT_EQ((FilterCallback*)NULL, filter_1_callback_);
+  EXPECT_EQ((FilterCallback*)NULL, filter_2_callback_);
+
+  // Stop playback.
+  DoStop();
+
+  // At this point we should be in the kStopped state.
+
+  // Try calling Stop() again to make sure neither filter is called.
+  EXPECT_CALL(*mock_callback, OnFilterCallback());
+
+  composite_->Stop(mock_callback->NewCallback());
+
+  // Verify that neither of the filter callbacks were set.
+  EXPECT_EQ((FilterCallback*)NULL, filter_1_callback_);
+  EXPECT_EQ((FilterCallback*)NULL, filter_2_callback_);
+
+  // Try calling Play() again to make sure we get an error.
+  ExpectInvalidStateFail(PLAY);
+}
+
+// Test errors in the middle of a serial call sequence like Play().
+TEST_F(CompositeFilterTest, TestPlayErrors) {
+  InSequence sequence;
+
+  SetupAndAdd2Filters();
+
+  scoped_ptr<StrictMock<MockFilterCallback> > mock_callback(
+      new StrictMock<MockFilterCallback>(false));
+
+  EXPECT_CALL(*filter_1_, Play(_));
+
+  // Call Play() on the composite.
+  composite_->Play(mock_callback->NewCallback());
+
+  EXPECT_CALL(*filter_2_, Play(_));
+
+  // Run callback to indicate that |filter_1_|'s Play() has completed.
+  RunFilter1Callback();
+
+  // At this point Play() has been called on |filter_2_|. Simulate an
+  // error by calling SetError() on its FilterHost interface.
+  filter_2_->host()->SetError(PIPELINE_ERROR_OUT_OF_MEMORY);
+
+  // Expect error to be reported and "play done" callback to be called.
+  EXPECT_CALL(*mock_filter_host_, SetError(PIPELINE_ERROR_OUT_OF_MEMORY));
+  EXPECT_CALL(*mock_callback, OnFilterCallback());
+
+  // Run callback to indicate that |filter_2_|'s Play() has completed.
+  RunFilter2Callback();
+
+  // Verify that Play/Pause/Flush/Seek fail now that an error occured.
+  ExpectInvalidStateFail(PLAY);
+  ExpectInvalidStateFail(PAUSE);
+  ExpectInvalidStateFail(FLUSH);
+  ExpectInvalidStateFail(SEEK);
+
+  // Make sure you can still Stop().
+  DoStop();
+}
+
+TEST_F(CompositeFilterTest, TestPause) {
+  InSequence sequence;
+
+  SetupAndAdd2Filters();
+
+  scoped_ptr<StrictMock<MockFilterCallback> > mock_callback(
+      new StrictMock<MockFilterCallback>(false));
+
+  // Try calling Pause() to make sure we get an error because we aren't in
+  // the playing state.
+  ExpectInvalidStateFail(PAUSE);
+
+  // Transition to playing state.
+  DoPlay();
+
+  // Issue a successful Pause().
+  DoPause();
+
+  // At this point we are paused.
+
+  // Try calling Pause() again to make sure that the filters aren't called
+  // because we are already in the paused state.
+  EXPECT_CALL(*mock_callback, OnFilterCallback());
+
+  composite_->Pause(mock_callback->NewCallback());
+
+  // Verify that neither of the filter callbacks were set.
+  EXPECT_EQ((FilterCallback*)NULL, filter_1_callback_);
+  EXPECT_EQ((FilterCallback*)NULL, filter_2_callback_);
+
+  // Verify that we can transition pack to the play state.
+  DoPlay();
+
+  // Go back to the pause state.
+  DoPause();
+
+  // Transition to the stop state.
+  DoStop();
+
+  // Try calling Pause() to make sure we get an error because we aren't in
+  // the playing state.
+  ExpectInvalidStateFail(PAUSE);
+}
+
+// Test errors in the middle of a serial call sequence like Pause().
+TEST_F(CompositeFilterTest, TestPauseErrors) {
+  InSequence sequence;
+
+  SetupAndAdd2Filters();
+
+  DoPlay();
+
+  scoped_ptr<StrictMock<MockFilterCallback> > mock_callback(
+      new StrictMock<MockFilterCallback>(false));
+
+  EXPECT_CALL(*filter_1_, Pause(_));
+
+  // Call Pause() on the composite.
+  composite_->Pause(mock_callback->NewCallback());
+
+  // Simulate an error by calling SetError() on |filter_1_|'s FilterHost
+  // interface.
+  filter_1_->host()->SetError(PIPELINE_ERROR_OUT_OF_MEMORY);
+
+  // Expect error to be reported and "pause done" callback to be called.
+  EXPECT_CALL(*mock_filter_host_, SetError(PIPELINE_ERROR_OUT_OF_MEMORY));
+  EXPECT_CALL(*mock_callback, OnFilterCallback());
+
+  RunFilter1Callback();
+
+  // Make sure |filter_2_callback_| was not set.
+  EXPECT_EQ((FilterCallback*)NULL, filter_2_callback_);
+
+  // Verify that Play/Pause/Flush/Seek fail now that an error occured.
+  ExpectInvalidStateFail(PLAY);
+  ExpectInvalidStateFail(PAUSE);
+  ExpectInvalidStateFail(FLUSH);
+  ExpectInvalidStateFail(SEEK);
+
+  // Make sure you can still Stop().
+  DoStop();
+}
+
+TEST_F(CompositeFilterTest, TestFlush) {
+  InSequence sequence;
+
+  SetupAndAdd2Filters();
+
+  scoped_ptr<StrictMock<MockFilterCallback> > mock_callback(
+      new StrictMock<MockFilterCallback>(false));
+
+  // Make sure Flush() works before calling Play().
+  DoFlush();
+
+  // Transition to playing state.
+  DoPlay();
+
+  // Call Flush() to make sure we get an error because we are in
+  // the playing state.
+  ExpectInvalidStateFail(FLUSH);
+
+  // Issue a successful Pause().
+  DoPause();
+
+  // Make sure Flush() works after pausing.
+  DoFlush();
+
+  // Verify that we can transition back to the play state.
+  DoPlay();
+
+  // Transition to the stop state.
+  DoStop();
+
+  // Try calling Flush() to make sure we get an error because we are stopped.
+  ExpectInvalidStateFail(FLUSH);
+}
+
+// Test errors in the middle of a parallel call sequence like Flush().
+TEST_F(CompositeFilterTest, TestFlushErrors) {
+  InSequence sequence;
+
+  SetupAndAdd2Filters();
+
+  scoped_ptr<StrictMock<MockFilterCallback> > mock_callback(
+      new StrictMock<MockFilterCallback>(false));
+
+  EXPECT_CALL(*filter_1_, Flush(_));
+  EXPECT_CALL(*filter_2_, Flush(_));
+
+  // Call Flush() on the composite.
+  composite_->Flush(mock_callback->NewCallback());
+
+  // Simulate an error by calling SetError() on |filter_1_|'s FilterHost
+  // interface.
+  filter_1_->host()->SetError(PIPELINE_ERROR_OUT_OF_MEMORY);
+
+  RunFilter1Callback();
+
+  // Expect error to be reported and "pause done" callback to be called.
+  EXPECT_CALL(*mock_filter_host_, SetError(PIPELINE_ERROR_OUT_OF_MEMORY));
+  EXPECT_CALL(*mock_callback, OnFilterCallback());
+
+  RunFilter2Callback();
+
+  // Verify that Play/Pause/Flush/Seek fail now that an error occured.
+  ExpectInvalidStateFail(PLAY);
+  ExpectInvalidStateFail(PAUSE);
+  ExpectInvalidStateFail(FLUSH);
+  ExpectInvalidStateFail(SEEK);
+
+  // Make sure you can still Stop().
+  DoStop();
+}
+
+TEST_F(CompositeFilterTest, TestSeek) {
+  InSequence sequence;
+
+  SetupAndAdd2Filters();
+
+  // Verify that seek is allowed to be called before a Play() call.
+  DoSeek(base::TimeDelta::FromSeconds(5));
+
+  // Verify we can issue a Play() after the Seek().
+  DoPlay();
+
+  scoped_ptr<StrictMock<MockFilterCallback> > mock_callback(
+      new StrictMock<MockFilterCallback>(false));
+
+  // Try calling Seek() while playing to make sure we get an error.
+  ExpectInvalidStateFail(SEEK);
+
+  // Transition to paused state.
+  DoPause();
+
+  // Verify that seek is allowed after pausing.
+  DoSeek(base::TimeDelta::FromSeconds(5));
+
+  // Verify we can still play again.
+  DoPlay();
+
+  // Stop playback.
+  DoStop();
+
+  // Try calling Seek() to make sure we get an error.
+  ExpectInvalidStateFail(SEEK);
+}
+
+TEST_F(CompositeFilterTest, TestStop) {
+  InSequence sequence;
+
+  // Test Stop() before any other call.
+  SetupAndAdd2Filters();
+  DoStop();
+
+  // Test error during Stop() sequence.
+  SetupAndAdd2Filters();
+  scoped_ptr<StrictMock<MockFilterCallback> > mock_callback(
+      new StrictMock<MockFilterCallback>(false));
+
+  EXPECT_CALL(*filter_1_, Stop(_));
+
+  composite_->Stop(mock_callback->NewCallback());
+
+  // Have |filter_1_| signal an error.
+  filter_1_->host()->SetError(PIPELINE_ERROR_READ);
+
+  EXPECT_CALL(*filter_2_, Stop(_));
+
+  RunFilter1Callback();
+
+  EXPECT_CALL(*mock_callback, OnFilterCallback());
+
+  RunFilter2Callback();
+}
+
+// Test stopping in the middle of a serial call sequence.
+TEST_F(CompositeFilterTest, TestStopWhilePlayPending) {
+  InSequence sequence;
+
+  SetupAndAdd2Filters();
+
+  scoped_ptr<StrictMock<MockFilterCallback> > mock_callback(
+      new StrictMock<MockFilterCallback>());
+
+  EXPECT_CALL(*filter_1_, Play(_));
+
+  composite_->Play(mock_callback->NewCallback());
+
+  // Note: Play() is pending on |filter_1_| right now.
+
+  scoped_ptr<StrictMock<MockFilterCallback> > mock_callback_2(
+      new StrictMock<MockFilterCallback>(false));
+
+  EXPECT_CALL(*mock_callback, OnCallbackDestroyed());
+
+  composite_->Stop(mock_callback_2->NewCallback());
+
+  EXPECT_CALL(*filter_1_, Stop(_));
+
+  // Run |filter_1_|'s callback again to indicate Play() has completed.
+  RunFilter1Callback();
+
+  EXPECT_CALL(*filter_2_, Stop(_));
+
+  // Run |filter_1_|'s callback again to indicate Stop() has completed.
+  RunFilter1Callback();
+
+  EXPECT_CALL(*mock_callback_2, OnFilterCallback());
+
+  // Run |filter_2_|'s callback to indicate Stop() has completed.
+  RunFilter2Callback();
+}
+
+// Test stopping in the middle of a parallel call sequence.
+TEST_F(CompositeFilterTest, TestStopWhileFlushPending) {
+  InSequence sequence;
+
+  SetupAndAdd2Filters();
+
+  scoped_ptr<StrictMock<MockFilterCallback> > mock_callback(
+      new StrictMock<MockFilterCallback>());
+
+  EXPECT_CALL(*filter_1_, Flush(_));
+  EXPECT_CALL(*filter_2_, Flush(_));
+
+  composite_->Flush(mock_callback->NewCallback());
+
+  // Note: |filter_1_| and |filter_2_| have pending Flush() calls at this point.
+
+  scoped_ptr<StrictMock<MockFilterCallback> > mock_callback_2(
+      new StrictMock<MockFilterCallback>(false));
+
+  EXPECT_CALL(*mock_callback, OnCallbackDestroyed());
+
+  composite_->Stop(mock_callback_2->NewCallback());
+
+  // Run callback to indicate that |filter_1_|'s Flush() has completed.
+  RunFilter1Callback();
+
+  EXPECT_CALL(*filter_1_, Stop(_));
+
+  // Run callback to indicate that |filter_2_|'s Flush() has completed.
+  RunFilter2Callback();
+
+  EXPECT_CALL(*filter_2_, Stop(_));
+
+  // Run callback to indicate that |filter_1_|'s Stop() has completed.
+  RunFilter1Callback();
+
+  EXPECT_CALL(*mock_callback_2, OnFilterCallback());
+
+  // Run callback to indicate that |filter_2_|'s Stop() has completed.
+  RunFilter2Callback();
+}
+
+TEST_F(CompositeFilterTest, TestErrorWhilePlaying) {
+  InSequence sequence;
+
+  SetupAndAdd2Filters();
+
+  // Simulate an error on |filter_2_| while in kCreated state. This
+  // can happen if an error occurs during filter initialization.
+  EXPECT_CALL(*mock_filter_host_, SetError(PIPELINE_ERROR_OUT_OF_MEMORY));
+  filter_2_->host()->SetError(PIPELINE_ERROR_OUT_OF_MEMORY);
+
+  DoPlay();
+
+  // Simulate an error on |filter_2_| while playing.
+  EXPECT_CALL(*mock_filter_host_, SetError(PIPELINE_ERROR_OUT_OF_MEMORY));
+  filter_2_->host()->SetError(PIPELINE_ERROR_OUT_OF_MEMORY);
+
+  DoPause();
+
+  // Simulate an error on |filter_2_| while paused.
+  EXPECT_CALL(*mock_filter_host_, SetError(PIPELINE_ERROR_NETWORK));
+  filter_2_->host()->SetError(PIPELINE_ERROR_NETWORK);
+
+  DoStop();
+
+  // Verify that errors are not passed to |mock_filter_host_|
+  // after Stop() has been called.
+  filter_2_->host()->SetError(PIPELINE_ERROR_NETWORK);
+}
+
+// Make sure that state transitions act as expected even
+// if the composite doesn't contain any filters.
+TEST_F(CompositeFilterTest, TestEmptyComposite) {
+  InSequence sequence;
+
+  composite_->set_host(mock_filter_host_.get());
+
+  scoped_ptr<StrictMock<MockFilterCallback> > mock_callback(
+      new StrictMock<MockFilterCallback>(false));
+
+  // Issue a Play() and expect no errors.
+  EXPECT_CALL(*mock_callback, OnFilterCallback());
+  composite_->Play(mock_callback->NewCallback());
+
+  // Issue a Pause() and expect no errors.
+  EXPECT_CALL(*mock_callback, OnFilterCallback());
+  composite_->Pause(mock_callback->NewCallback());
+
+  // Issue a Flush() and expect no errors.
+  EXPECT_CALL(*mock_callback, OnFilterCallback());
+  composite_->Flush(mock_callback->NewCallback());
+
+  // Issue a Seek() and expect no errors.
+  EXPECT_CALL(*mock_callback, OnFilterCallback());
+  composite_->Seek(base::TimeDelta::FromSeconds(5),
+                   mock_callback->NewCallback());
+
+  // Issue a Play() and expect no errors.
+  EXPECT_CALL(*mock_callback, OnFilterCallback());
+  composite_->Play(mock_callback->NewCallback());
+
+  // Issue a Stop() and expect no errors.
+  EXPECT_CALL(*mock_callback, OnFilterCallback());
+  composite_->Stop(mock_callback->NewCallback());
+}
+
+}  // namespace media