Allow unit tests to use a mock audio input controller.

This is modelled after chrome/common/net/test_url_fetcher_factory.h. Using this mock unit tests can stub out the audio recording part and test the consumer of the audio data.
I have also added a new media_test_support target to media.gyp, this will be used in subsequent CLs for testing speech input code.
BUG=none
TEST=none, this code will get used in future unit tests

Review URL: http://codereview.chromium.org/3148003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@55627 0039d316-1c4b-4281-b951-d872f2087c98

4 files changed, 179 insertions, 3 deletions

diff --git a/media/audio/audio_input_controller.cc b/media/audio/audio_input_controller.cc
index f94c0042..d64fb70 100644
--- a/media/audio/audio_input_controller.cc
+++ b/media/audio/audio_input_controller.cc
@@ -15,6 +15,9 @@ const int kMaxSamplesPerPacket = kMaxSampleRate;
 
 namespace media {
 
+// static
+AudioInputController::Factory* AudioInputController::factory_ = NULL;
+
 AudioInputController::AudioInputController(EventHandler* handler)
     : handler_(handler),
       stream_(NULL),
@@ -40,6 +43,11 @@ scoped_refptr<AudioInputController> AudioInputController::Create(
       (samples_per_packet > kMaxSamplesPerPacket) || (samples_per_packet < 0))
     return NULL;
 
+  if (factory_) {
+    return factory_->Create(event_handler, format, channels, sample_rate,
+                            bits_per_sample, samples_per_packet);
+  }
+
   scoped_refptr<AudioInputController> controller = new AudioInputController(
       event_handler);
 
diff --git a/media/audio/audio_input_controller.h b/media/audio/audio_input_controller.h
index 27b3a54..a00e2bc 100644
--- a/media/audio/audio_input_controller.h
+++ b/media/audio/audio_input_controller.h
@@ -49,6 +49,21 @@ class AudioInputController :
                         uint32 size) = 0;
   };
 
+  // AudioInputController::Create uses the currently registered Factory to
+  // create the AudioInputController. Factory is intended for testing.
+  class Factory {
+   public:
+    virtual AudioInputController* Create(EventHandler* event_handler,
+                                         AudioManager::Format format,
+                                         int channels,
+                                         int sample_rate,
+                                         int bits_per_sample,
+                                         int samples_per_packet) = 0;
+
+   protected:
+    virtual ~Factory() {}
+  };
+
   virtual ~AudioInputController();
 
   // Factory method for creating an AudioInputController.
@@ -63,8 +78,15 @@ class AudioInputController :
       int bits_per_sample,            // Number of bits per sample.
       int samples_per_packet);        // Size of the hardware buffer.
 
+  // Sets the factory used by the static method Create. AudioInputController
+  // does not take ownership of |factory|. A value of NULL results in an
+  // AudioInputController being created directly.
+#if defined(UNIT_TEST)
+  static void set_factory(Factory* factory) { factory_ = factory; }
+#endif
+
   // Starts recording in this audio input stream.
-  void Record();
+  virtual void Record();
 
   // Closes the audio input stream and shutdown the audio input controller
   // thread. This method returns only after all operations are completed. This
@@ -72,7 +94,7 @@ class AudioInputController :
   //
   // It is safe to call this method more than once. Calls after the first one
   // will have no effect.
-  void Close();
+  virtual void Close();
 
   ///////////////////////////////////////////////////////////////////////////
   // AudioInputCallback methods.
@@ -80,7 +102,7 @@ class AudioInputController :
   virtual void OnClose(AudioInputStream* stream);
   virtual void OnError(AudioInputStream* stream, int code);
 
- private:
+ protected:
   // Internal state of the source.
   enum State {
     kEmpty,
@@ -113,6 +135,8 @@ class AudioInputController :
   // The audio input controller thread that this object runs on.
   base::Thread thread_;
 
+  static Factory* factory_;
+
   DISALLOW_COPY_AND_ASSIGN(AudioInputController);
 };
 
diff --git a/media/audio/test_audio_input_controller_factory.cc b/media/audio/test_audio_input_controller_factory.cc
new file mode 100644
index 0000000..c56afd8
--- /dev/null
+++ b/media/audio/test_audio_input_controller_factory.cc
@@ -0,0 +1,44 @@
+// Copyright (c) 2009 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/audio/test_audio_input_controller_factory.h"
+#include "media/audio/audio_io.h"
+
+namespace media {
+
+TestAudioInputController::TestAudioInputController(
+    TestAudioInputControllerFactory* factory, EventHandler* event_handler)
+    : AudioInputController(event_handler),
+      factory_(factory),
+      event_handler_(event_handler) {
+}
+
+TestAudioInputController::~TestAudioInputController() {
+  // Inform the factory so that it allows creating new instances in future.
+  factory_->OnTestAudioInputControllerDestroyed(this);
+}
+
+TestAudioInputControllerFactory::TestAudioInputControllerFactory()
+    : controller_(NULL) {
+}
+
+AudioInputController* TestAudioInputControllerFactory::Create(
+    AudioInputController::EventHandler* event_handler,
+    AudioManager::Format format,
+    int channels,
+    int sample_rate,
+    int bits_per_sample,
+    int samples_per_packet) {
+  DCHECK(!controller_);  // Only one test instance managed at a time.
+  controller_ = new TestAudioInputController(this, event_handler);
+  return controller_;
+}
+
+void TestAudioInputControllerFactory::OnTestAudioInputControllerDestroyed(
+    TestAudioInputController* controller) {
+  DCHECK(controller_ == controller);
+  controller_ = NULL;
+}
+
+}  // namespace media
diff --git a/media/audio/test_audio_input_controller_factory.h b/media/audio/test_audio_input_controller_factory.h
new file mode 100644
index 0000000..bd8f7b9
--- /dev/null
+++ b/media/audio/test_audio_input_controller_factory.h
@@ -0,0 +1,100 @@
+// Copyright (c) 2009 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.
+
+#ifndef MEDIA_AUDIO_TEST_AUDIO_INPUT_CONTROLLER_FACTORY_H_
+#define MEDIA_AUDIO_TEST_AUDIO_INPUT_CONTROLLER_FACTORY_H_
+#pragma once
+
+#include "media/audio/audio_input_controller.h"
+
+namespace media {
+
+class TestAudioInputControllerFactory;
+
+// TestAudioInputController and TestAudioInputControllerFactory are used for
+// testing consumers of AudioInputController. TestAudioInputControllerFactory
+// is a AudioInputController::Factory that creates TestAudioInputControllers.
+//
+// TestAudioInputController::Record and Close are overriden to do nothing. It is
+// expected that you'll grab the EventHandler from the TestAudioInputController
+// and invoke the callback methods when appropriate. In this way it's easy to
+// mock a AudioInputController.
+//
+// Typical usage:
+//   // Create and register factory.
+//   TestAudioInputControllerFactory factory;
+//   AudioInputController::set_factory(&factory);
+//
+//   // Do something that triggers creation of an AudioInputController.
+//   TestAudioInputController* controller = factory.last_controller();
+//   DCHECK(controller);
+//
+//   // Notify event handler with whatever data you want.
+//   controller->event_handler()->OnCreated(...);
+//
+//   // Do something that triggers AudioInputController::Record to be called.
+//   controller->event_handler()->OnData(...);
+//   controller->event_handler()->OnError(...);
+//
+//   // Make sure consumer of AudioInputController does the right thing.
+//   ...
+//   // Reset factory.
+//   AudioInputController::set_factory(NULL);
+
+class TestAudioInputController : public AudioInputController {
+ public:
+  TestAudioInputController(TestAudioInputControllerFactory* factory,
+                           EventHandler* event_handler);
+  virtual ~TestAudioInputController();
+
+  // Returns the event handler installed on the AudioInputController.
+  EventHandler* event_handler() const { return event_handler_; }
+
+  // Overriden to do nothing. It is assumed the caller will notify the event
+  // handler with recorded data and other events.
+  virtual void Record() {}
+  virtual void Close() {}
+
+ private:
+  // These are not owned by us and expected to be valid for this object's
+  // lifetime.
+  TestAudioInputControllerFactory* factory_;
+  EventHandler* event_handler_;
+
+  DISALLOW_COPY_AND_ASSIGN(TestAudioInputController);
+};
+
+// Simple AudioInputController::Factory method that creates
+// TestAudioInputControllers.
+class TestAudioInputControllerFactory : public AudioInputController::Factory {
+ public:
+  TestAudioInputControllerFactory();
+
+  // AudioInputController::Factory methods.
+  AudioInputController* Create(
+      AudioInputController::EventHandler* event_handler,
+      AudioManager::Format format,
+      int channels,
+      int sample_rate,
+      int bits_per_sample,
+      int samples_per_packet);
+
+  TestAudioInputController* controller() const { return controller_; }
+
+ private:
+  friend class TestAudioInputController;
+
+  // Invoked by a TestAudioInputController when it gets destroyed.
+  void OnTestAudioInputControllerDestroyed(
+      TestAudioInputController* controller);
+
+  // The caller of Create owns this object.
+  TestAudioInputController* controller_;
+
+  DISALLOW_COPY_AND_ASSIGN(TestAudioInputControllerFactory);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_AUDIO_TEST_AUDIO_INPUT_CONTROLLER_FACTORY_H_