Web MIDI: introduce pending client count limit to start sessions

media/midi/midi_manager_unittest.cc

 // Copyright 2014 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/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"
 
 namespace media {
 
 namespace {
 
 class FakeMidiManager : public MidiManager {
  public:
   FakeMidiManager() : start_initialization_is_called_(false) {}
@@ skipping 31 matching lines @@
 class FakeMidiManagerClient : public MidiManagerClient {
  public:
   explicit FakeMidiManagerClient(int client_id)
       : client_id_(client_id),
         result_(MIDI_NOT_SUPPORTED),
         wait_for_result_(true) {}
   virtual ~FakeMidiManagerClient() {}
 
   // 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;
   }
 
   virtual void ReceiveMidiData(uint32 port_index, const uint8* data,
                                size_t size, double timestamp) OVERRIDE {}
   virtual void AccumulateMidiBytesSent(size_t size) OVERRIDE {}
 
   int get_client_id() const { return client_id_; }
@@ skipping 12 matching lines @@
   int client_id_;
   MidiResult result_;
   bool wait_for_result_;
 
   DISALLOW_COPY_AND_ASSIGN(FakeMidiManagerClient);
 };
 
 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:
   void StartTheFirstSession(FakeMidiManagerClient* client) {
     EXPECT_FALSE(manager_->start_initialization_is_called_);
     EXPECT_EQ(0U, manager_->GetClientCount());
     EXPECT_EQ(0U, manager_->GetPendingClientCount());
     manager_->StartSession(client, client->get_client_id());
     EXPECT_EQ(0U, manager_->GetClientCount());
     EXPECT_EQ(1U, manager_->GetPendingClientCount());
     EXPECT_TRUE(manager_->start_initialization_is_called_);
     EXPECT_EQ(0U, manager_->GetClientCount());
     EXPECT_EQ(1U, manager_->GetPendingClientCount());
     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) {
     EXPECT_EQ(before, manager_->GetClientCount());
     manager_->EndSession(client);
     EXPECT_EQ(after, manager_->GetClientCount());
   }
 
   void CompleteInitialization(MidiResult result) {
     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);
 };
 
 TEST_F(MidiManagerTest, StartAndEndSession) {
   scoped_ptr<FakeMidiManagerClient> client;
   client.reset(new FakeMidiManagerClient(0));
 
   StartTheFirstSession(client.get());
   CompleteInitialization(MIDI_OK);
@@ skipping 11 matching lines @@
   EndSession(client.get(), 0U, 0U);
 }
 
 TEST_F(MidiManagerTest, StartMultipleSessions) {
   scoped_ptr<FakeMidiManagerClient> client1;
   scoped_ptr<FakeMidiManagerClient> client2;
   client1.reset(new FakeMidiManagerClient(0));
   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());
   EndSession(client1.get(), 2U, 1U);
   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));
 
   scoped_ptr<MidiManager> manager(MidiManager::Create());
   manager->StartSession(client.get(), client->get_client_id());
   EXPECT_EQ(MIDI_OK, client->WaitForResult());
 }
 
 }  // namespace
 
 }  // namespace media