Add support for attaching filters to an IPC TestSink.

The filters can see every message that is sent to the sink, which is useful
when if the test is waiting for a specific message to arrive.

BUG=none
TEST=none

Review URL: http://codereview.chromium.org/6387007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@73194 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 48 insertions, 0 deletions

diff --git a/ipc/ipc_test_sink.cc b/ipc/ipc_test_sink.cc
index 95900b6..4404239 100644
--- a/ipc/ipc_test_sink.cc
+++ b/ipc/ipc_test_sink.cc
@@ -21,6 +21,14 @@ bool TestSink::Send(Message* message) {
 }
 
 bool TestSink::OnMessageReceived(const Message& msg) {
+  ObserverListBase<Channel::Listener>::Iterator it(filter_list_);
+  Channel::Listener* observer;
+  while ((observer = it.GetNext()) != NULL) {
+    if (observer->OnMessageReceived(msg))
+      return true;
+  }
+
+  // No filter handled the message, so store it.
   messages_.push_back(Message(msg));
   return true;
 }
@@ -57,4 +65,12 @@ const Message* TestSink::GetUniqueMessageMatching(uint32 id) const {
   return &messages_[found_index];
 }
 
+void TestSink::AddFilter(Channel::Listener* filter) {
+  filter_list_.AddObserver(filter);
+}
+
+void TestSink::RemoveFilter(Channel::Listener* filter) {
+  filter_list_.RemoveObserver(filter);
+}
+
 }  // namespace IPC
diff --git a/ipc/ipc_test_sink.h b/ipc/ipc_test_sink.h
index c6114f1..d0895aa 100644
--- a/ipc/ipc_test_sink.h
+++ b/ipc/ipc_test_sink.h
@@ -10,6 +10,7 @@
 #include <vector>
 
 #include "base/basictypes.h"
+#include "base/observer_list.h"
 #include "ipc/ipc_channel.h"
 
 namespace IPC {
@@ -41,6 +42,26 @@ class Message;
 //   // Go on to the next phase of the test.
 //   test_sink.ClearMessages();
 //
+// You can also register to be notified when messages are posted to the sink.
+// This can be useful if you need to wait for a particular message that will
+// be posted asynchronously.  Example usage:
+//
+//   class MyListener : public IPC::Channel::Listener {
+//    public:
+//     virtual bool OnMessageReceived(const IPC::Message& msg) {
+//       <do something with the message>
+//       MessageLoop::current()->Quit();
+//       return false;  // to store the message in the sink, or true to drop it
+//     }
+//   };
+//
+//   MyListener listener;
+//   test_sink.AddFilter(&listener);
+//   StartSomeAsynchronousProcess(&test_sink);
+//   MessageLoop::current()->Run();
+//   <inspect the results>
+//   ...
+//
 // To hook up the sink, all you need to do is call OnMessageReceived when a
 // message is received.
 class TestSink : public Channel {
@@ -79,9 +100,20 @@ class TestSink : public Channel {
   // or the list is cleared.
   const Message* GetUniqueMessageMatching(uint32 id) const;
 
+  // Adds the given listener as a filter to the TestSink.
+  // When a message is received by the TestSink, it will be dispatched to
+  // the filters, in the order they were added.  If a filter returns true
+  // from OnMessageReceived, subsequent filters will not receive the message
+  // and the TestSink will not store it.
+  void AddFilter(Channel::Listener* filter);
+
+  // Removes the given filter from the TestSink.
+  void RemoveFilter(Channel::Listener* filter);
+
  private:
   // The actual list of received messages.
   std::vector<Message> messages_;
+  ObserverList<Channel::Listener> filter_list_;
 
   DISALLOW_COPY_AND_ASSIGN(TestSink);
 };