Web MIDI: introduce pending client count limit to start sessions

media/midi/midi_manager_unittest.cc

Index: media/midi/midi_manager_unittest.cc
diff --git a/media/midi/midi_manager_unittest.cc b/media/midi/midi_manager_unittest.cc
index 456c2b0988ebcadf5931dcd11cc9b23231eb887e..5811665fed1ee21344a6dfb72768c03c266cdf49 100644
--- a/media/midi/midi_manager_unittest.cc
+++ b/media/midi/midi_manager_unittest.cc
@@ -4,8 +4,11 @@
 
 #include "media/midi/midi_manager.h"
 
+#include <vector>
+
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/memory/scoped_vector.h"
 #include "base/run_loop.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ -57,6 +60,7 @@ class FakeMidiManagerClient : public MidiManagerClient {
 
   // MidiManagerClient implementation.
   virtual void CompleteStartSession(int client_id, MidiResult result) OVERRIDE {
+    EXPECT_TRUE(wait_for_result_);
     CHECK_EQ(client_id_, client_id);
     result_ = result;
     wait_for_result_ = false;
@@ -89,7 +93,8 @@ class FakeMidiManagerClient : public MidiManagerClient {
 class MidiManagerTest : public ::testing::Test {
  public:
   MidiManagerTest()
-      : message_loop_(new base::MessageLoop), manager_(new FakeMidiManager) {}
+      : manager_(new FakeMidiManager),
+        message_loop_(new base::MessageLoop) {}
   virtual ~MidiManagerTest() {}
 
  protected:
@@ -106,15 +111,17 @@ class MidiManagerTest : public ::testing::Test {
     EXPECT_TRUE(manager_->start_initialization_is_called_);
   }
 
-  void StartTheSecondSession(FakeMidiManagerClient* client) {
-    EXPECT_TRUE(manager_->start_initialization_is_called_);
+  void StartTheNthSession(FakeMidiManagerClient* client, size_t nth) {
+    EXPECT_EQ(nth != 1, manager_->start_initialization_is_called_);
     EXPECT_EQ(0U, manager_->GetClientCount());
-    EXPECT_EQ(1U, manager_->GetPendingClientCount());
+    EXPECT_EQ(nth - 1, manager_->GetPendingClientCount());
 
-    // StartInitialization() should not be called for the second session.
+    // StartInitialization() should not be called for the second and later
+    // sessions.
     manager_->start_initialization_is_called_ = false;
     manager_->StartSession(client, client->get_client_id());
-    EXPECT_FALSE(manager_->start_initialization_is_called_);
+    EXPECT_EQ(nth == 1, manager_->start_initialization_is_called_);
+    manager_->start_initialization_is_called_ = true;
   }
 
   void EndSession(FakeMidiManagerClient* client, size_t before, size_t after) {
@@ -127,9 +134,16 @@ class MidiManagerTest : public ::testing::Test {
     manager_->CallCompleteInitialization(result);
   }
 
+  void RunLoopUntilIdle() {
+    base::RunLoop run_loop;
+    run_loop.RunUntilIdle();
+  }
+
+ protected:
+  scoped_ptr<FakeMidiManager> manager_;
+
  private:
   scoped_ptr<base::MessageLoop> message_loop_;
-  scoped_ptr<FakeMidiManager> manager_;
 
   DISALLOW_COPY_AND_ASSIGN(MidiManagerTest);
 };
@@ -161,7 +175,7 @@ TEST_F(MidiManagerTest, StartMultipleSessions) {
   client2.reset(new FakeMidiManagerClient(1));
 
   StartTheFirstSession(client1.get());
-  StartTheSecondSession(client2.get());
+  StartTheNthSession(client2.get(), 2);
   CompleteInitialization(MIDI_OK);
   EXPECT_EQ(MIDI_OK, client1->WaitForResult());
   EXPECT_EQ(MIDI_OK, client2->WaitForResult());
@@ -169,6 +183,39 @@ TEST_F(MidiManagerTest, StartMultipleSessions) {
   EndSession(client2.get(), 1U, 0U);
 }
 
+TEST_F(MidiManagerTest, TooManyPendingSessions) {
+  // Push as many client requests for starting session as possible.
+  ScopedVector<FakeMidiManagerClient> clients;

[yukawa, 2014/05/07 00:07:13]

I feel |clients| and |client| are typographically too similar and it is a bit
hard to distinguish one from the other.

How about using a bit more descriptive names here?
Examples:
- |clients| -> |many_existing_clients|
- |client| -> |additional_client|
Anyway, feel free to choose names that you like.

[Takashi Toyoshima, 2014/05/07 02:09:11]

Sound reasonable.
Done.

+  clients.resize(MidiManager::kMaxPendingClientCount);
+  for (size_t i = 0; i < MidiManager::kMaxPendingClientCount; ++i) {
+    clients[i] = new FakeMidiManagerClient(i);
+    StartTheNthSession(clients[i], i + 1);
+  }
+
+  // Push the last client that should be rejected for too many pending requests.
+  scoped_ptr<FakeMidiManagerClient> client(
+      new FakeMidiManagerClient(MidiManager::kMaxPendingClientCount));
+  manager_->start_initialization_is_called_ = false;
+  manager_->StartSession(client.get(), client->get_client_id());
+  EXPECT_FALSE(manager_->start_initialization_is_called_);
+  EXPECT_EQ(MIDI_INITIALIZATION_ERROR, client->get_result());
+
+  // Other clients still should not receive a result.
+  RunLoopUntilIdle();
+  for (size_t i = 0; i < clients.size(); ++i)
+    EXPECT_EQ(MIDI_NOT_SUPPORTED, clients[i]->get_result());
+
+  // The result MIDI_OK should be distributed to other clients.
+  CompleteInitialization(MIDI_OK);
+  for (size_t i = 0; i < clients.size(); ++i)
+    EXPECT_EQ(MIDI_OK, clients[i]->WaitForResult());
+
+  // Close all successful sessions in FIFO order.
+  size_t sessions = clients.size();
+  for (size_t i = 0; i < clients.size(); ++i, --sessions)
+    EndSession(clients[i], sessions, sessions - 1);
+}
+
 TEST_F(MidiManagerTest, CreateMidiManager) {
   scoped_ptr<FakeMidiManagerClient> client;
   client.reset(new FakeMidiManagerClient(0));