tor-browser

ports_unittest.cc (53595B)

---

// Copyright 2016 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 <inttypes.h>
#include <stdio.h>

#include <map>
#include <utility>

#include "base/logging.h"
#include "base/waitable_event.h"
#include "base/thread.h"
#include "base/string_util.h"
#include "mojo/core/ports/event.h"
#include "mojo/core/ports/node.h"
#include "mojo/core/ports/node_delegate.h"
#include "mojo/core/ports/port_locker.h"
#include "mojo/core/ports/user_message.h"
#include "testing/gtest/include/gtest/gtest.h"

#include "mozilla/Mutex.h"

namespace mojo {
namespace core {
namespace ports {
namespace test {

namespace {

// TODO(rockot): Remove this unnecessary alias.
using ScopedMessage = mozilla::UniquePtr<UserMessageEvent>;

class TestMessage : public UserMessage {
public:
 static const TypeInfo kUserMessageTypeInfo;

 explicit TestMessage(const std::string& payload)
     : UserMessage(&kUserMessageTypeInfo), payload_(payload) {}
 ~TestMessage() override = default;

 const std::string& payload() const { return payload_; }

private:
 std::string payload_;
};

const UserMessage::TypeInfo TestMessage::kUserMessageTypeInfo = {};

ScopedMessage NewUserMessageEvent(const std::string& payload,
                                 size_t num_ports) {
 auto event = mozilla::MakeUnique<UserMessageEvent>(num_ports);
 event->AttachMessage(mozilla::MakeUnique<TestMessage>(payload));
 return event;
}

bool MessageEquals(const ScopedMessage& message, const std::string& s) {
 return message->GetMessage<TestMessage>()->payload() == s;
}

class TestNode;

class MessageRouter {
public:
 virtual ~MessageRouter() = default;

 virtual void ForwardEvent(TestNode* from_node, const NodeName& node_name,
                           ScopedEvent event) = 0;
 virtual void BroadcastEvent(TestNode* from_node, ScopedEvent event) = 0;
};

class TestNode : public NodeDelegate {
public:
 explicit TestNode(uint64_t id)
     : node_name_(id, 1),
       node_(node_name_, this),
       node_thread_(StringPrintf("Node %" PRIu64 " thread", id).c_str()),
       events_available_event_(/* manual_reset */ false,
                               /* initially_signaled */ false),
       idle_event_(/* manual_reset */ true, /* initially_signaled */ true) {}

 ~TestNode() override {
   StopWhenIdle();
   node_thread_.Stop();
 }

 const NodeName& name() const { return node_name_; }

 // NOTE: Node is thread-safe.
 Node& node() { return node_; }

 base::WaitableEvent& idle_event() { return idle_event_; }

 bool IsIdle() {
   mozilla::MutexAutoLock lock(lock_);
   return started_ && !dispatching_ &&
          (incoming_events_.empty() || (block_on_event_ && blocked_));
 }

 void BlockOnEvent(Event::Type type) {
   mozilla::MutexAutoLock lock(lock_);
   blocked_event_type_ = type;
   block_on_event_ = true;
 }

 void Unblock() {
   mozilla::MutexAutoLock lock(lock_);
   block_on_event_ = false;
   events_available_event_.Signal();
 }

 void Start(MessageRouter* router) {
   router_ = router;
   node_thread_.Start();
   node_thread_.message_loop()->PostTask(mozilla::NewNonOwningRunnableMethod(
       "TestNode::ProcessEvents", this, &TestNode::ProcessEvents));
 }

 void StopWhenIdle() {
   mozilla::MutexAutoLock lock(lock_);
   should_quit_ = true;
   events_available_event_.Signal();
 }

 void WakeUp() { events_available_event_.Signal(); }

 int SendStringMessage(const PortRef& port, const std::string& s) {
   return node_.SendUserMessage(port, NewUserMessageEvent(s, 0));
 }

 int SendMultipleMessages(const PortRef& port, size_t num_messages) {
   for (size_t i = 0; i < num_messages; ++i) {
     int result = SendStringMessage(port, "");
     if (result != OK) {
       return result;
     }
   }
   return OK;
 }

 int SendStringMessageWithPort(const PortRef& port, const std::string& s,
                               const PortName& sent_port_name) {
   auto event = NewUserMessageEvent(s, 1);
   event->ports()[0] = sent_port_name;
   return node_.SendUserMessage(port, std::move(event));
 }

 int SendStringMessageWithPort(const PortRef& port, const std::string& s,
                               const PortRef& sent_port) {
   return SendStringMessageWithPort(port, s, sent_port.name());
 }

 void set_drop_messages(bool value) {
   mozilla::MutexAutoLock lock(lock_);
   drop_messages_ = value;
 }

 void set_save_messages(bool value) {
   mozilla::MutexAutoLock lock(lock_);
   save_messages_ = value;
 }

 bool ReadMessage(const PortRef& port, ScopedMessage* message) {
   return node_.GetMessage(port, message, nullptr) == OK && *message;
 }

 bool ReadMultipleMessages(const PortRef& port, size_t num_messages) {
   for (size_t i = 0; i < num_messages; ++i) {
     ScopedMessage message;
     if (!ReadMessage(port, &message)) {
       return false;
     }
   }
   return true;
 }

 bool GetSavedMessage(ScopedMessage* message) {
   mozilla::MutexAutoLock lock(lock_);
   if (saved_messages_.empty()) {
     message->reset();
     return false;
   }
   std::swap(*message, saved_messages_.front());
   saved_messages_.pop();
   return true;
 }

 void EnqueueEvent(const NodeName& from_node, ScopedEvent event) {
   idle_event_.Reset();

   // NOTE: This may be called from ForwardMessage and thus must not reenter
   // |node_|.
   mozilla::MutexAutoLock lock(lock_);
   incoming_events_.push({from_node, std::move(event)});
   events_available_event_.Signal();
 }

 void ForwardEvent(const NodeName& node_name, ScopedEvent event) override {
   {
     mozilla::MutexAutoLock lock(lock_);
     if (drop_messages_) {
       DVLOG(1) << "Dropping ForwardMessage from node " << node_name_ << " to "
                << node_name;

       mozilla::MutexAutoUnlock unlock(lock_);
       ClosePortsInEvent(event.get());
       return;
     }
   }

   DCHECK(router_);
   DVLOG(1) << "ForwardEvent from node " << node_name_ << " to " << node_name;
   router_->ForwardEvent(this, node_name, std::move(event));
 }

 void BroadcastEvent(ScopedEvent event) override {
   router_->BroadcastEvent(this, std::move(event));
 }

 void PortStatusChanged(const PortRef& port) override {
   // The port may be closed, in which case we ignore the notification.
   mozilla::MutexAutoLock lock(lock_);
   if (!save_messages_) {
     return;
   }

   for (;;) {
     ScopedMessage message;
     {
       mozilla::MutexAutoUnlock unlock(lock_);
       if (!ReadMessage(port, &message)) {
         break;
       }
     }

     saved_messages_.emplace(std::move(message));
   }
 }

 void ObserveRemoteNode(const NodeName& node) override {
   DCHECK(node != node_name_);
 }

 void ClosePortsInEvent(Event* event) {
   if (event->type() != Event::Type::kUserMessage) {
     return;
   }

   UserMessageEvent* message_event = static_cast<UserMessageEvent*>(event);
   for (size_t i = 0; i < message_event->num_ports(); ++i) {
     PortRef port;
     ASSERT_EQ(OK, node_.GetPort(message_event->ports()[i], &port));
     EXPECT_EQ(OK, node_.ClosePort(port));
   }
 }

 uint64_t GetUnacknowledgedMessageCount(const PortRef& port_ref) {
   PortStatus status{};
   if (node_.GetStatus(port_ref, &status) != OK) {
     return 0;
   }

   return status.unacknowledged_message_count;
 }

 void AllowPortMerge(const PortRef& port_ref) {
   SinglePortLocker locker(&port_ref);
   locker.port()->pending_merge_peer = true;
 }

private:
 void ProcessEvents() {
   for (;;) {
     events_available_event_.Wait();
     mozilla::MutexAutoLock lock(lock_);

     if (should_quit_) {
       return;
     }

     dispatching_ = true;
     while (!incoming_events_.empty()) {
       if (block_on_event_ &&
           incoming_events_.front().second->type() == blocked_event_type_) {
         blocked_ = true;
         // Go idle if we hit a blocked event type.
         break;
       }
       blocked_ = false;

       auto node_event_pair = std::move(incoming_events_.front());
       incoming_events_.pop();

       // NOTE: AcceptMessage() can re-enter this object to call any of the
       // NodeDelegate interface methods.
       mozilla::MutexAutoUnlock unlock(lock_);
       node_.AcceptEvent(node_event_pair.first,
                         std::move(node_event_pair.second));
     }

     dispatching_ = false;
     started_ = true;
     idle_event_.Signal();
   };
 }

 const NodeName node_name_;
 Node node_;
 MessageRouter* router_ = nullptr;

 base::Thread node_thread_;
 base::WaitableEvent events_available_event_;
 base::WaitableEvent idle_event_;

 // Guards fields below.
 mozilla::Mutex lock_ MOZ_UNANNOTATED{"TestNode"};
 bool started_ = false;
 bool dispatching_ = false;
 bool should_quit_ = false;
 bool drop_messages_ = false;
 bool save_messages_ = false;
 bool blocked_ = false;
 bool block_on_event_ = false;
 Event::Type blocked_event_type_{};
 std::queue<std::pair<NodeName, ScopedEvent>> incoming_events_;
 std::queue<ScopedMessage> saved_messages_;
};

class PortsTest : public testing::Test, public MessageRouter {
public:
 void AddNode(TestNode* node) {
   {
     mozilla::MutexAutoLock lock(lock_);
     nodes_[node->name()] = node;
   }
   node->Start(this);
 }

 void RemoveNode(TestNode* node) {
   {
     mozilla::MutexAutoLock lock(lock_);
     nodes_.erase(node->name());
   }

   for (const auto& entry : nodes_) {
     entry.second->node().LostConnectionToNode(node->name());
   }
 }

 // Waits until all known Nodes are idle. Message forwarding and processing
 // is handled in such a way that idleness is a stable state: once all nodes in
 // the system are idle, they will remain idle until the test explicitly
 // initiates some further event (e.g. sending a message, closing a port, or
 // removing a Node).
 void WaitForIdle() {
   for (;;) {
     mozilla::MutexAutoLock global_lock(global_lock_);
     bool all_nodes_idle = true;
     for (const auto& entry : nodes_) {
       if (!entry.second->IsIdle()) {
         all_nodes_idle = false;
       }
       entry.second->WakeUp();
     }
     if (all_nodes_idle) {
       return;
     }

     // Wait for any Node to signal that it's idle.
     mozilla::MutexAutoUnlock global_unlock(global_lock_);
     std::vector<base::WaitableEvent*> events;
     for (const auto& entry : nodes_) {
       events.push_back(&entry.second->idle_event());
     }
     base::WaitableEvent::WaitMany(events.data(), events.size());
   }
 }

 void CreatePortPair(TestNode* node0, PortRef* port0, TestNode* node1,
                     PortRef* port1) {
   if (node0 == node1) {
     EXPECT_EQ(OK, node0->node().CreatePortPair(port0, port1));
   } else {
     EXPECT_EQ(OK, node0->node().CreateUninitializedPort(port0));
     EXPECT_EQ(OK, node1->node().CreateUninitializedPort(port1));
     EXPECT_EQ(
         OK, node0->node().InitializePort(*port0, node1->name(), port1->name(),
                                          node1->name(), port1->name()));
     EXPECT_EQ(
         OK, node1->node().InitializePort(*port1, node0->name(), port0->name(),
                                          node0->name(), port0->name()));
   }
 }

private:
 // MessageRouter:
 void ForwardEvent(TestNode* from_node, const NodeName& node_name,
                   ScopedEvent event) override {
   mozilla::MutexAutoLock global_lock(global_lock_);
   mozilla::MutexAutoLock lock(lock_);
   // Drop messages from nodes that have been removed.
   if (nodes_.find(from_node->name()) == nodes_.end()) {
     from_node->ClosePortsInEvent(event.get());
     return;
   }

   auto it = nodes_.find(node_name);
   if (it == nodes_.end()) {
     DVLOG(1) << "Node not found: " << node_name;
     return;
   }

   // Serialize and de-serialize all forwarded events.
   size_t buf_size = event->GetSerializedSize();
   mozilla::UniquePtr<char[]> buf(new char[buf_size]);
   event->Serialize(buf.get());
   ScopedEvent copy = Event::Deserialize(buf.get(), buf_size);
   // This should always succeed unless serialization or deserialization
   // is broken. In that case, the loss of events should cause a test failure.
   ASSERT_TRUE(copy);

   // Also copy the payload for user messages.
   if (event->type() == Event::Type::kUserMessage) {
     UserMessageEvent* message_event =
         static_cast<UserMessageEvent*>(event.get());
     UserMessageEvent* message_copy =
         static_cast<UserMessageEvent*>(copy.get());

     message_copy->AttachMessage(mozilla::MakeUnique<TestMessage>(
         message_event->GetMessage<TestMessage>()->payload()));
   }

   it->second->EnqueueEvent(from_node->name(), std::move(event));
 }

 void BroadcastEvent(TestNode* from_node, ScopedEvent event) override {
   mozilla::MutexAutoLock global_lock(global_lock_);
   mozilla::MutexAutoLock lock(lock_);

   // Drop messages from nodes that have been removed.
   if (nodes_.find(from_node->name()) == nodes_.end()) {
     return;
   }

   for (const auto& entry : nodes_) {
     TestNode* node = entry.second;
     // Broadcast doesn't deliver to the local node.
     if (node == from_node) {
       continue;
     }
     node->EnqueueEvent(from_node->name(), event->CloneForBroadcast());
   }
 }

 // Acquired before any operation which makes a Node busy, and before testing
 // if all nodes are idle.
 mozilla::Mutex global_lock_ MOZ_UNANNOTATED{"PortsTest Global Lock"};

 mozilla::Mutex lock_ MOZ_UNANNOTATED{"PortsTest Lock"};
 std::map<NodeName, TestNode*> nodes_;
};

}  // namespace

TEST_F(PortsTest, Basic1) {
 TestNode node0(0);
 AddNode(&node0);

 TestNode node1(1);
 AddNode(&node1);

 PortRef x0, x1;
 CreatePortPair(&node0, &x0, &node1, &x1);

 PortRef a0, a1;
 EXPECT_EQ(OK, node0.node().CreatePortPair(&a0, &a1));
 EXPECT_EQ(OK, node0.SendStringMessageWithPort(x0, "hello", a1));
 EXPECT_EQ(OK, node0.node().ClosePort(a0));

 EXPECT_EQ(OK, node0.node().ClosePort(x0));
 EXPECT_EQ(OK, node1.node().ClosePort(x1));

 WaitForIdle();

 EXPECT_TRUE(node0.node().CanShutdownCleanly());
 EXPECT_TRUE(node1.node().CanShutdownCleanly());
}

TEST_F(PortsTest, Basic2) {
 TestNode node0(0);
 AddNode(&node0);

 TestNode node1(1);
 AddNode(&node1);

 PortRef x0, x1;
 CreatePortPair(&node0, &x0, &node1, &x1);

 PortRef b0, b1;
 EXPECT_EQ(OK, node0.node().CreatePortPair(&b0, &b1));
 EXPECT_EQ(OK, node0.SendStringMessageWithPort(x0, "hello", b1));
 EXPECT_EQ(OK, node0.SendStringMessage(b0, "hello again"));

 EXPECT_EQ(OK, node0.node().ClosePort(b0));

 EXPECT_EQ(OK, node0.node().ClosePort(x0));
 EXPECT_EQ(OK, node1.node().ClosePort(x1));

 WaitForIdle();

 EXPECT_TRUE(node0.node().CanShutdownCleanly());
 EXPECT_TRUE(node1.node().CanShutdownCleanly());
}

TEST_F(PortsTest, Basic3) {
 TestNode node0(0);
 AddNode(&node0);

 TestNode node1(1);
 AddNode(&node1);

 PortRef x0, x1;
 CreatePortPair(&node0, &x0, &node1, &x1);

 PortRef a0, a1;
 EXPECT_EQ(OK, node0.node().CreatePortPair(&a0, &a1));

 EXPECT_EQ(OK, node0.SendStringMessageWithPort(x0, "hello", a1));
 EXPECT_EQ(OK, node0.SendStringMessage(a0, "hello again"));

 EXPECT_EQ(OK, node0.SendStringMessageWithPort(x0, "foo", a0));

 PortRef b0, b1;
 EXPECT_EQ(OK, node0.node().CreatePortPair(&b0, &b1));
 EXPECT_EQ(OK, node0.SendStringMessageWithPort(x0, "bar", b1));
 EXPECT_EQ(OK, node0.SendStringMessage(b0, "baz"));

 EXPECT_EQ(OK, node0.node().ClosePort(b0));

 EXPECT_EQ(OK, node0.node().ClosePort(x0));
 EXPECT_EQ(OK, node1.node().ClosePort(x1));

 WaitForIdle();

 EXPECT_TRUE(node0.node().CanShutdownCleanly());
 EXPECT_TRUE(node1.node().CanShutdownCleanly());
}

TEST_F(PortsTest, LostConnectionToNode1) {
 TestNode node0(0);
 AddNode(&node0);

 TestNode node1(1);
 AddNode(&node1);
 node1.set_drop_messages(true);

 PortRef x0, x1;
 CreatePortPair(&node0, &x0, &node1, &x1);

 // Transfer a port to node1 and simulate a lost connection to node1.

 PortRef a0, a1;
 EXPECT_EQ(OK, node0.node().CreatePortPair(&a0, &a1));
 EXPECT_EQ(OK, node0.SendStringMessageWithPort(x0, "foo", a1));

 WaitForIdle();

 RemoveNode(&node1);

 WaitForIdle();

 EXPECT_EQ(OK, node0.node().ClosePort(a0));
 EXPECT_EQ(OK, node0.node().ClosePort(x0));
 EXPECT_EQ(OK, node1.node().ClosePort(x1));

 WaitForIdle();

 EXPECT_TRUE(node0.node().CanShutdownCleanly());
 EXPECT_TRUE(node1.node().CanShutdownCleanly());
}

TEST_F(PortsTest, LostConnectionToNode2) {
 TestNode node0(0);
 AddNode(&node0);

 TestNode node1(1);
 AddNode(&node1);

 PortRef x0, x1;
 CreatePortPair(&node0, &x0, &node1, &x1);

 PortRef a0, a1;
 EXPECT_EQ(OK, node0.node().CreatePortPair(&a0, &a1));
 EXPECT_EQ(OK, node0.SendStringMessageWithPort(x0, "take a1", a1));

 WaitForIdle();

 node1.set_drop_messages(true);

 RemoveNode(&node1);

 WaitForIdle();

 // a0 should have eventually detected peer closure after node loss.
 ScopedMessage message;
 EXPECT_EQ(ERROR_PORT_PEER_CLOSED,
           node0.node().GetMessage(a0, &message, nullptr));
 EXPECT_FALSE(message);

 EXPECT_EQ(OK, node0.node().ClosePort(a0));

 EXPECT_EQ(OK, node0.node().ClosePort(x0));

 EXPECT_EQ(OK, node1.node().GetMessage(x1, &message, nullptr));
 EXPECT_TRUE(message);
 node1.ClosePortsInEvent(message.get());

 EXPECT_EQ(OK, node1.node().ClosePort(x1));

 WaitForIdle();

 EXPECT_TRUE(node0.node().CanShutdownCleanly());
 EXPECT_TRUE(node1.node().CanShutdownCleanly());
}

TEST_F(PortsTest, LostConnectionToNodeWithSecondaryProxy) {
 // Tests that a proxy gets cleaned up when its indirect peer lives on a lost
 // node.

 TestNode node0(0);
 AddNode(&node0);

 TestNode node1(1);
 AddNode(&node1);

 TestNode node2(2);
 AddNode(&node2);

 // Create A-B spanning nodes 0 and 1 and C-D spanning 1 and 2.
 PortRef A, B, C, D;
 CreatePortPair(&node0, &A, &node1, &B);
 CreatePortPair(&node1, &C, &node2, &D);

 // Create E-F and send F over A to node 1.
 PortRef E, F;
 EXPECT_EQ(OK, node0.node().CreatePortPair(&E, &F));
 EXPECT_EQ(OK, node0.SendStringMessageWithPort(A, ".", F));

 WaitForIdle();

 ScopedMessage message;
 ASSERT_TRUE(node1.ReadMessage(B, &message));
 ASSERT_EQ(1u, message->num_ports());

 EXPECT_EQ(OK, node1.node().GetPort(message->ports()[0], &F));

 // Send F over C to node 2 and then simulate node 2 loss from node 1. Node 1
 // will trivially become aware of the loss, and this test verifies that the
 // port A on node 0 will eventually also become aware of it.

 // Make sure node2 stops processing events when it encounters an ObserveProxy.
 node2.BlockOnEvent(Event::Type::kObserveProxy);

 EXPECT_EQ(OK, node1.SendStringMessageWithPort(C, ".", F));
 WaitForIdle();

 // Simulate node 1 and 2 disconnecting.
 EXPECT_EQ(OK, node1.node().LostConnectionToNode(node2.name()));

 // Let node2 continue processing events and wait for everyone to go idle.
 node2.Unblock();
 WaitForIdle();

 // Port F should be gone.
 EXPECT_EQ(ERROR_PORT_UNKNOWN, node1.node().GetPort(F.name(), &F));

 // Port E should have detected peer closure despite the fact that there is
 // no longer a continuous route from F to E over which the event could travel.
 PortStatus status{};
 EXPECT_EQ(OK, node0.node().GetStatus(E, &status));
 EXPECT_TRUE(status.peer_closed);

 EXPECT_EQ(OK, node0.node().ClosePort(A));
 EXPECT_EQ(OK, node1.node().ClosePort(B));
 EXPECT_EQ(OK, node1.node().ClosePort(C));
 EXPECT_EQ(OK, node0.node().ClosePort(E));

 WaitForIdle();

 EXPECT_TRUE(node0.node().CanShutdownCleanly());
 EXPECT_TRUE(node1.node().CanShutdownCleanly());
}

TEST_F(PortsTest, LostConnectionToNodeAfterSendingObserveProxy) {
 // Tests that a proxy gets cleaned up after a node disconnect if the
 // previous port already received the ObserveProxy event.

 TestNode node0(0);
 AddNode(&node0);

 TestNode node1(1);
 AddNode(&node1);

 TestNode node2(2);
 AddNode(&node2);

 // Create A-B spanning nodes 0 and 1 and C-D spanning 1 and 2.
 PortRef A, B, C, D;
 CreatePortPair(&node0, &A, &node1, &B);
 CreatePortPair(&node1, &C, &node2, &D);

 // Create E-F and send F over A to node 1.
 PortRef E, F;
 EXPECT_EQ(OK, node0.node().CreatePortPair(&E, &F));
 EXPECT_EQ(OK, node0.SendStringMessageWithPort(A, ".", F));

 WaitForIdle();

 ScopedMessage message;
 ASSERT_TRUE(node1.ReadMessage(B, &message));
 ASSERT_EQ(1u, message->num_ports());

 EXPECT_EQ(OK, node1.node().GetPort(message->ports()[0], &F));

 // Send F over C to node 2 and then simulate node 2 loss from node 1 after
 // node 0 received the ObserveProxy event. Node 1 needs to clean up the
 // closed proxy while the node 0 to node 2 connection is still intact.
 node0.BlockOnEvent(Event::Type::kObserveProxy);

 EXPECT_EQ(OK, node1.SendStringMessageWithPort(C, ".", F));
 WaitForIdle();

 // Simulate node 1 and 2 disconnecting.
 EXPECT_EQ(OK, node1.node().LostConnectionToNode(node2.name()));

 // Let node2 continue processing events and wait for everyone to go idle.
 node0.Unblock();
 WaitForIdle();

 // Port F should be gone.
 EXPECT_EQ(ERROR_PORT_UNKNOWN, node1.node().GetPort(F.name(), &F));

 EXPECT_EQ(OK, node0.node().ClosePort(A));
 EXPECT_EQ(OK, node1.node().ClosePort(B));
 EXPECT_EQ(OK, node1.node().ClosePort(C));
 EXPECT_EQ(OK, node0.node().ClosePort(E));

 WaitForIdle();

 EXPECT_TRUE(node0.node().CanShutdownCleanly());
 EXPECT_TRUE(node1.node().CanShutdownCleanly());
}

TEST_F(PortsTest, LostConnectionToNodeWithLocalProxy) {
 // Tests that a proxy gets cleaned up when its direct peer lives on a lost
 // node and it's predecessor lives on the same node.

 TestNode node0(0);
 AddNode(&node0);

 TestNode node1(1);
 AddNode(&node1);

 PortRef A, B;
 CreatePortPair(&node0, &A, &node1, &B);

 PortRef C, D;
 EXPECT_EQ(OK, node0.node().CreatePortPair(&C, &D));

 // Send D but block node0 on an ObserveProxy event.
 node0.BlockOnEvent(Event::Type::kObserveProxy);
 EXPECT_EQ(OK, node0.SendStringMessageWithPort(A, ".", D));

 // node0 won't collapse the proxy but node1 will receive the message before
 // going idle.
 WaitForIdle();

 ScopedMessage message;
 ASSERT_TRUE(node1.ReadMessage(B, &message));
 ASSERT_EQ(1u, message->num_ports());
 PortRef E;
 EXPECT_EQ(OK, node1.node().GetPort(message->ports()[0], &E));

 RemoveNode(&node1);

 node0.Unblock();
 WaitForIdle();

 // Port C should have detected peer closure.
 PortStatus status{};
 EXPECT_EQ(OK, node0.node().GetStatus(C, &status));
 EXPECT_TRUE(status.peer_closed);

 EXPECT_EQ(OK, node0.node().ClosePort(A));
 EXPECT_EQ(OK, node1.node().ClosePort(B));
 EXPECT_EQ(OK, node0.node().ClosePort(C));
 EXPECT_EQ(OK, node1.node().ClosePort(E));

 EXPECT_TRUE(node0.node().CanShutdownCleanly());
 EXPECT_TRUE(node1.node().CanShutdownCleanly());
}

TEST_F(PortsTest, GetMessage1) {
 TestNode node(0);
 AddNode(&node);

 PortRef a0, a1;
 EXPECT_EQ(OK, node.node().CreatePortPair(&a0, &a1));

 ScopedMessage message;
 EXPECT_EQ(OK, node.node().GetMessage(a0, &message, nullptr));
 EXPECT_FALSE(message);

 EXPECT_EQ(OK, node.node().ClosePort(a1));

 WaitForIdle();

 EXPECT_EQ(ERROR_PORT_PEER_CLOSED,
           node.node().GetMessage(a0, &message, nullptr));
 EXPECT_FALSE(message);

 EXPECT_EQ(OK, node.node().ClosePort(a0));

 WaitForIdle();

 EXPECT_TRUE(node.node().CanShutdownCleanly());
}

TEST_F(PortsTest, GetMessage2) {
 TestNode node(0);
 AddNode(&node);

 PortRef a0, a1;
 EXPECT_EQ(OK, node.node().CreatePortPair(&a0, &a1));

 EXPECT_EQ(OK, node.SendStringMessage(a1, "1"));

 ScopedMessage message;
 EXPECT_EQ(OK, node.node().GetMessage(a0, &message, nullptr));

 ASSERT_TRUE(message);
 EXPECT_TRUE(MessageEquals(message, "1"));

 EXPECT_EQ(OK, node.node().ClosePort(a0));
 EXPECT_EQ(OK, node.node().ClosePort(a1));

 EXPECT_TRUE(node.node().CanShutdownCleanly());
}

TEST_F(PortsTest, GetMessage3) {
 TestNode node(0);
 AddNode(&node);

 PortRef a0, a1;
 EXPECT_EQ(OK, node.node().CreatePortPair(&a0, &a1));

 const char* kStrings[] = {"1", "2", "3"};

 for (auto& kString : kStrings) {
   EXPECT_EQ(OK, node.SendStringMessage(a1, kString));
 }

 ScopedMessage message;
 for (auto& kString : kStrings) {
   EXPECT_EQ(OK, node.node().GetMessage(a0, &message, nullptr));
   ASSERT_TRUE(message);
   EXPECT_TRUE(MessageEquals(message, kString));
 }

 EXPECT_EQ(OK, node.node().ClosePort(a0));
 EXPECT_EQ(OK, node.node().ClosePort(a1));

 EXPECT_TRUE(node.node().CanShutdownCleanly());
}

TEST_F(PortsTest, Delegation1) {
 TestNode node0(0);
 AddNode(&node0);

 TestNode node1(1);
 AddNode(&node1);

 PortRef x0, x1;
 CreatePortPair(&node0, &x0, &node1, &x1);

 // In this test, we send a message to a port that has been moved.

 PortRef a0, a1;
 EXPECT_EQ(OK, node0.node().CreatePortPair(&a0, &a1));
 EXPECT_EQ(OK, node0.SendStringMessageWithPort(x0, "a1", a1));
 WaitForIdle();

 ScopedMessage message;
 ASSERT_TRUE(node1.ReadMessage(x1, &message));
 ASSERT_EQ(1u, message->num_ports());
 EXPECT_TRUE(MessageEquals(message, "a1"));

 // This is "a1" from the point of view of node1.
 PortName a2_name = message->ports()[0];
 EXPECT_EQ(OK, node1.SendStringMessageWithPort(x1, "a2", a2_name));
 EXPECT_EQ(OK, node0.SendStringMessage(a0, "hello"));

 WaitForIdle();

 ASSERT_TRUE(node0.ReadMessage(x0, &message));
 ASSERT_EQ(1u, message->num_ports());
 EXPECT_TRUE(MessageEquals(message, "a2"));

 // This is "a2" from the point of view of node1.
 PortName a3_name = message->ports()[0];

 PortRef a3;
 EXPECT_EQ(OK, node0.node().GetPort(a3_name, &a3));

 ASSERT_TRUE(node0.ReadMessage(a3, &message));
 EXPECT_EQ(0u, message->num_ports());
 EXPECT_TRUE(MessageEquals(message, "hello"));

 EXPECT_EQ(OK, node0.node().ClosePort(a0));
 EXPECT_EQ(OK, node0.node().ClosePort(a3));

 EXPECT_EQ(OK, node0.node().ClosePort(x0));
 EXPECT_EQ(OK, node1.node().ClosePort(x1));

 EXPECT_TRUE(node0.node().CanShutdownCleanly());
 EXPECT_TRUE(node1.node().CanShutdownCleanly());
}

TEST_F(PortsTest, Delegation2) {
 TestNode node0(0);
 AddNode(&node0);

 TestNode node1(1);
 AddNode(&node1);

 for (int i = 0; i < 100; ++i) {
   // Setup pipe a<->b between node0 and node1.
   PortRef A, B;
   CreatePortPair(&node0, &A, &node1, &B);

   PortRef C, D;
   EXPECT_EQ(OK, node0.node().CreatePortPair(&C, &D));

   PortRef E, F;
   EXPECT_EQ(OK, node0.node().CreatePortPair(&E, &F));

   node1.set_save_messages(true);

   // Pass D over A to B.
   EXPECT_EQ(OK, node0.SendStringMessageWithPort(A, "1", D));

   // Pass F over C to D.
   EXPECT_EQ(OK, node0.SendStringMessageWithPort(C, "1", F));

   // This message should find its way to node1.
   EXPECT_EQ(OK, node0.SendStringMessage(E, "hello"));

   WaitForIdle();

   EXPECT_EQ(OK, node0.node().ClosePort(C));
   EXPECT_EQ(OK, node0.node().ClosePort(E));

   EXPECT_EQ(OK, node0.node().ClosePort(A));
   EXPECT_EQ(OK, node1.node().ClosePort(B));

   bool got_hello = false;
   ScopedMessage message;
   while (node1.GetSavedMessage(&message)) {
     node1.ClosePortsInEvent(message.get());
     if (MessageEquals(message, "hello")) {
       got_hello = true;
       break;
     }
   }

   EXPECT_TRUE(got_hello);

   WaitForIdle();  // Because closing ports may have generated tasks.
 }

 EXPECT_TRUE(node0.node().CanShutdownCleanly());
 EXPECT_TRUE(node1.node().CanShutdownCleanly());
}

TEST_F(PortsTest, SendUninitialized) {
 TestNode node(0);
 AddNode(&node);

 PortRef x0;
 EXPECT_EQ(OK, node.node().CreateUninitializedPort(&x0));
 EXPECT_EQ(ERROR_PORT_STATE_UNEXPECTED, node.SendStringMessage(x0, "oops"));
 EXPECT_EQ(OK, node.node().ClosePort(x0));
 EXPECT_TRUE(node.node().CanShutdownCleanly());
}

TEST_F(PortsTest, SendFailure) {
 TestNode node(0);
 AddNode(&node);

 node.set_save_messages(true);

 PortRef A, B;
 EXPECT_EQ(OK, node.node().CreatePortPair(&A, &B));

 // Try to send A over itself.

 EXPECT_EQ(ERROR_PORT_CANNOT_SEND_SELF,
           node.SendStringMessageWithPort(A, "oops", A));

 // Try to send B over A.

 EXPECT_EQ(ERROR_PORT_CANNOT_SEND_PEER,
           node.SendStringMessageWithPort(A, "nope", B));

 // B should be closed immediately.
 EXPECT_EQ(ERROR_PORT_UNKNOWN, node.node().GetPort(B.name(), &B));

 WaitForIdle();

 // There should have been no messages accepted.
 ScopedMessage message;
 EXPECT_FALSE(node.GetSavedMessage(&message));

 EXPECT_EQ(OK, node.node().ClosePort(A));

 WaitForIdle();

 EXPECT_TRUE(node.node().CanShutdownCleanly());
}

TEST_F(PortsTest, DontLeakUnreceivedPorts) {
 TestNode node(0);
 AddNode(&node);

 PortRef A, B, C, D;
 EXPECT_EQ(OK, node.node().CreatePortPair(&A, &B));
 EXPECT_EQ(OK, node.node().CreatePortPair(&C, &D));

 EXPECT_EQ(OK, node.SendStringMessageWithPort(A, "foo", D));

 EXPECT_EQ(OK, node.node().ClosePort(C));
 EXPECT_EQ(OK, node.node().ClosePort(A));
 EXPECT_EQ(OK, node.node().ClosePort(B));

 WaitForIdle();

 EXPECT_TRUE(node.node().CanShutdownCleanly());
}

TEST_F(PortsTest, AllowShutdownWithLocalPortsOpen) {
 TestNode node(0);
 AddNode(&node);

 PortRef A, B, C, D;
 EXPECT_EQ(OK, node.node().CreatePortPair(&A, &B));
 EXPECT_EQ(OK, node.node().CreatePortPair(&C, &D));

 EXPECT_EQ(OK, node.SendStringMessageWithPort(A, "foo", D));

 ScopedMessage message;
 EXPECT_TRUE(node.ReadMessage(B, &message));
 ASSERT_EQ(1u, message->num_ports());
 EXPECT_TRUE(MessageEquals(message, "foo"));
 PortRef E;
 ASSERT_EQ(OK, node.node().GetPort(message->ports()[0], &E));

 EXPECT_TRUE(
     node.node().CanShutdownCleanly(Node::ShutdownPolicy::ALLOW_LOCAL_PORTS));

 WaitForIdle();

 EXPECT_TRUE(
     node.node().CanShutdownCleanly(Node::ShutdownPolicy::ALLOW_LOCAL_PORTS));
 EXPECT_FALSE(node.node().CanShutdownCleanly());

 EXPECT_EQ(OK, node.node().ClosePort(A));
 EXPECT_EQ(OK, node.node().ClosePort(B));
 EXPECT_EQ(OK, node.node().ClosePort(C));
 EXPECT_EQ(OK, node.node().ClosePort(E));

 WaitForIdle();

 EXPECT_TRUE(node.node().CanShutdownCleanly());
}

TEST_F(PortsTest, ProxyCollapse1) {
 TestNode node(0);
 AddNode(&node);

 PortRef A, B;
 EXPECT_EQ(OK, node.node().CreatePortPair(&A, &B));

 PortRef X, Y;
 EXPECT_EQ(OK, node.node().CreatePortPair(&X, &Y));

 ScopedMessage message;

 // Send B and receive it as C.
 EXPECT_EQ(OK, node.SendStringMessageWithPort(X, "foo", B));
 ASSERT_TRUE(node.ReadMessage(Y, &message));
 ASSERT_EQ(1u, message->num_ports());
 PortRef C;
 ASSERT_EQ(OK, node.node().GetPort(message->ports()[0], &C));

 // Send C and receive it as D.
 EXPECT_EQ(OK, node.SendStringMessageWithPort(X, "foo", C));
 ASSERT_TRUE(node.ReadMessage(Y, &message));
 ASSERT_EQ(1u, message->num_ports());
 PortRef D;
 ASSERT_EQ(OK, node.node().GetPort(message->ports()[0], &D));

 // Send D and receive it as E.
 EXPECT_EQ(OK, node.SendStringMessageWithPort(X, "foo", D));
 ASSERT_TRUE(node.ReadMessage(Y, &message));
 ASSERT_EQ(1u, message->num_ports());
 PortRef E;
 ASSERT_EQ(OK, node.node().GetPort(message->ports()[0], &E));

 EXPECT_EQ(OK, node.node().ClosePort(X));
 EXPECT_EQ(OK, node.node().ClosePort(Y));

 EXPECT_EQ(OK, node.node().ClosePort(A));
 EXPECT_EQ(OK, node.node().ClosePort(E));

 // The node should not idle until all proxies are collapsed.
 WaitForIdle();

 EXPECT_TRUE(node.node().CanShutdownCleanly());
}

TEST_F(PortsTest, ProxyCollapse2) {
 TestNode node(0);
 AddNode(&node);

 PortRef A, B;
 EXPECT_EQ(OK, node.node().CreatePortPair(&A, &B));

 PortRef X, Y;
 EXPECT_EQ(OK, node.node().CreatePortPair(&X, &Y));

 ScopedMessage message;

 // Send B and A to create proxies in each direction.
 EXPECT_EQ(OK, node.SendStringMessageWithPort(X, "foo", B));
 EXPECT_EQ(OK, node.SendStringMessageWithPort(X, "foo", A));

 EXPECT_EQ(OK, node.node().ClosePort(X));
 EXPECT_EQ(OK, node.node().ClosePort(Y));

 // At this point we have a scenario with:
 //
 // D -> [B] -> C -> [A]
 //
 // Ensure that the proxies can collapse. The sent ports will be closed
 // eventually as a result of Y's closure.

 WaitForIdle();

 EXPECT_TRUE(node.node().CanShutdownCleanly());
}

TEST_F(PortsTest, SendWithClosedPeer) {
 // This tests that if a port is sent when its peer is already known to be
 // closed, the newly created port will be aware of that peer closure, and the
 // proxy will eventually collapse.

 TestNode node(0);
 AddNode(&node);

 // Send a message from A to B, then close A.
 PortRef A, B;
 EXPECT_EQ(OK, node.node().CreatePortPair(&A, &B));
 EXPECT_EQ(OK, node.SendStringMessage(A, "hey"));
 EXPECT_EQ(OK, node.node().ClosePort(A));

 // Now send B over X-Y as new port C.
 PortRef X, Y;
 EXPECT_EQ(OK, node.node().CreatePortPair(&X, &Y));
 EXPECT_EQ(OK, node.SendStringMessageWithPort(X, "foo", B));
 ScopedMessage message;
 ASSERT_TRUE(node.ReadMessage(Y, &message));
 ASSERT_EQ(1u, message->num_ports());
 PortRef C;
 ASSERT_EQ(OK, node.node().GetPort(message->ports()[0], &C));

 EXPECT_EQ(OK, node.node().ClosePort(X));
 EXPECT_EQ(OK, node.node().ClosePort(Y));

 WaitForIdle();

 // C should have received the message originally sent to B, and it should also
 // be aware of A's closure.

 ASSERT_TRUE(node.ReadMessage(C, &message));
 EXPECT_TRUE(MessageEquals(message, "hey"));

 PortStatus status{};
 EXPECT_EQ(OK, node.node().GetStatus(C, &status));
 EXPECT_FALSE(status.receiving_messages);
 EXPECT_FALSE(status.has_messages);
 EXPECT_TRUE(status.peer_closed);

 node.node().ClosePort(C);

 WaitForIdle();

 EXPECT_TRUE(node.node().CanShutdownCleanly());
}

TEST_F(PortsTest, SendWithClosedPeerSent) {
 // This tests that if a port is closed while some number of proxies are still
 // routing messages (directly or indirectly) to it, that the peer port is
 // eventually notified of the closure, and the dead-end proxies will
 // eventually be removed.

 TestNode node(0);
 AddNode(&node);

 PortRef X, Y;
 EXPECT_EQ(OK, node.node().CreatePortPair(&X, &Y));

 PortRef A, B;
 EXPECT_EQ(OK, node.node().CreatePortPair(&A, &B));

 ScopedMessage message;

 // Send A as new port C.
 EXPECT_EQ(OK, node.SendStringMessageWithPort(X, "foo", A));

 ASSERT_TRUE(node.ReadMessage(Y, &message));
 ASSERT_EQ(1u, message->num_ports());
 PortRef C;
 ASSERT_EQ(OK, node.node().GetPort(message->ports()[0], &C));

 // Send C as new port D.
 EXPECT_EQ(OK, node.SendStringMessageWithPort(X, "foo", C));

 ASSERT_TRUE(node.ReadMessage(Y, &message));
 ASSERT_EQ(1u, message->num_ports());
 PortRef D;
 ASSERT_EQ(OK, node.node().GetPort(message->ports()[0], &D));

 // Send a message to B through D, then close D.
 EXPECT_EQ(OK, node.SendStringMessage(D, "hey"));
 EXPECT_EQ(OK, node.node().ClosePort(D));

 // Now send B as new port E.

 EXPECT_EQ(OK, node.SendStringMessageWithPort(X, "foo", B));
 EXPECT_EQ(OK, node.node().ClosePort(X));

 ASSERT_TRUE(node.ReadMessage(Y, &message));
 ASSERT_EQ(1u, message->num_ports());
 PortRef E;
 ASSERT_EQ(OK, node.node().GetPort(message->ports()[0], &E));

 EXPECT_EQ(OK, node.node().ClosePort(Y));

 WaitForIdle();

 // E should receive the message originally sent to B, and it should also be
 // aware of D's closure.

 ASSERT_TRUE(node.ReadMessage(E, &message));
 EXPECT_TRUE(MessageEquals(message, "hey"));

 PortStatus status{};
 EXPECT_EQ(OK, node.node().GetStatus(E, &status));
 EXPECT_FALSE(status.receiving_messages);
 EXPECT_FALSE(status.has_messages);
 EXPECT_TRUE(status.peer_closed);

 EXPECT_EQ(OK, node.node().ClosePort(E));

 WaitForIdle();

 EXPECT_TRUE(node.node().CanShutdownCleanly());
}

TEST_F(PortsTest, MergePorts) {
 TestNode node0(0);
 AddNode(&node0);

 TestNode node1(1);
 AddNode(&node1);

 // Setup two independent port pairs, A-B on node0 and C-D on node1.
 PortRef A, B, C, D;
 EXPECT_EQ(OK, node0.node().CreatePortPair(&A, &B));
 EXPECT_EQ(OK, node1.node().CreatePortPair(&C, &D));

 // Write a message on A.
 EXPECT_EQ(OK, node0.SendStringMessage(A, "hey"));

 // Initiate a merge between B and C.
 node1.AllowPortMerge(C);
 EXPECT_EQ(OK, node0.node().MergePorts(B, node1.name(), C.name()));

 WaitForIdle();

 // Expect all proxies to be gone once idle.
 EXPECT_TRUE(
     node0.node().CanShutdownCleanly(Node::ShutdownPolicy::ALLOW_LOCAL_PORTS));
 EXPECT_TRUE(
     node1.node().CanShutdownCleanly(Node::ShutdownPolicy::ALLOW_LOCAL_PORTS));

 // Expect D to have received the message sent on A.
 ScopedMessage message;
 ASSERT_TRUE(node1.ReadMessage(D, &message));
 EXPECT_TRUE(MessageEquals(message, "hey"));

 EXPECT_EQ(OK, node0.node().ClosePort(A));
 EXPECT_EQ(OK, node1.node().ClosePort(D));

 // No more ports should be open.
 EXPECT_TRUE(node0.node().CanShutdownCleanly());
 EXPECT_TRUE(node1.node().CanShutdownCleanly());
}

TEST_F(PortsTest, MergePortWithClosedPeer1) {
 // This tests that the right thing happens when initiating a merge on a port
 // whose peer has already been closed.

 TestNode node0(0);
 AddNode(&node0);

 TestNode node1(1);
 AddNode(&node1);

 // Setup two independent port pairs, A-B on node0 and C-D on node1.
 PortRef A, B, C, D;
 EXPECT_EQ(OK, node0.node().CreatePortPair(&A, &B));
 EXPECT_EQ(OK, node1.node().CreatePortPair(&C, &D));

 // Write a message on A.
 EXPECT_EQ(OK, node0.SendStringMessage(A, "hey"));

 // Close A.
 EXPECT_EQ(OK, node0.node().ClosePort(A));

 // Initiate a merge between B and C.
 node1.AllowPortMerge(C);
 EXPECT_EQ(OK, node0.node().MergePorts(B, node1.name(), C.name()));

 WaitForIdle();

 // Expect all proxies to be gone once idle. node0 should have no ports since
 // A was explicitly closed.
 EXPECT_TRUE(node0.node().CanShutdownCleanly());
 EXPECT_TRUE(
     node1.node().CanShutdownCleanly(Node::ShutdownPolicy::ALLOW_LOCAL_PORTS));

 // Expect D to have received the message sent on A.
 ScopedMessage message;
 ASSERT_TRUE(node1.ReadMessage(D, &message));
 EXPECT_TRUE(MessageEquals(message, "hey"));

 EXPECT_EQ(OK, node1.node().ClosePort(D));

 // No more ports should be open.
 EXPECT_TRUE(node0.node().CanShutdownCleanly());
 EXPECT_TRUE(node1.node().CanShutdownCleanly());
}

TEST_F(PortsTest, MergePortWithClosedPeer2) {
 // This tests that the right thing happens when merging into a port whose peer
 // has already been closed.

 TestNode node0(0);
 AddNode(&node0);

 TestNode node1(1);
 AddNode(&node1);

 // Setup two independent port pairs, A-B on node0 and C-D on node1.
 PortRef A, B, C, D;
 EXPECT_EQ(OK, node0.node().CreatePortPair(&A, &B));
 EXPECT_EQ(OK, node1.node().CreatePortPair(&C, &D));

 // Write a message on D and close it.
 EXPECT_EQ(OK, node1.SendStringMessage(D, "hey"));
 EXPECT_EQ(OK, node1.node().ClosePort(D));

 // Initiate a merge between B and C.
 node1.AllowPortMerge(C);
 EXPECT_EQ(OK, node0.node().MergePorts(B, node1.name(), C.name()));

 WaitForIdle();

 // Expect all proxies to be gone once idle. node1 should have no ports since
 // D was explicitly closed.
 EXPECT_TRUE(
     node0.node().CanShutdownCleanly(Node::ShutdownPolicy::ALLOW_LOCAL_PORTS));
 EXPECT_TRUE(node1.node().CanShutdownCleanly());

 // Expect A to have received the message sent on D.
 ScopedMessage message;
 ASSERT_TRUE(node0.ReadMessage(A, &message));
 EXPECT_TRUE(MessageEquals(message, "hey"));

 EXPECT_EQ(OK, node0.node().ClosePort(A));

 // No more ports should be open.
 EXPECT_TRUE(node0.node().CanShutdownCleanly());
 EXPECT_TRUE(node1.node().CanShutdownCleanly());
}

TEST_F(PortsTest, MergePortsWithClosedPeers) {
 // This tests that no residual ports are left behind if two ports are merged
 // when both of their peers have been closed.

 TestNode node0(0);
 AddNode(&node0);

 TestNode node1(1);
 AddNode(&node1);

 // Setup two independent port pairs, A-B on node0 and C-D on node1.
 PortRef A, B, C, D;
 EXPECT_EQ(OK, node0.node().CreatePortPair(&A, &B));
 EXPECT_EQ(OK, node1.node().CreatePortPair(&C, &D));

 // Close A and D.
 EXPECT_EQ(OK, node0.node().ClosePort(A));
 EXPECT_EQ(OK, node1.node().ClosePort(D));

 WaitForIdle();

 // Initiate a merge between B and C.
 node1.AllowPortMerge(C);
 EXPECT_EQ(OK, node0.node().MergePorts(B, node1.name(), C.name()));

 WaitForIdle();

 // Expect everything to have gone away.
 EXPECT_TRUE(node0.node().CanShutdownCleanly());
 EXPECT_TRUE(node1.node().CanShutdownCleanly());
}

TEST_F(PortsTest, MergePortsWithMovedPeers) {
 // This tests that ports can be merged successfully even if their peers are
 // moved around.

 TestNode node0(0);
 AddNode(&node0);

 TestNode node1(1);
 AddNode(&node1);

 // Setup two independent port pairs, A-B on node0 and C-D on node1.
 PortRef A, B, C, D;
 EXPECT_EQ(OK, node0.node().CreatePortPair(&A, &B));
 EXPECT_EQ(OK, node1.node().CreatePortPair(&C, &D));

 // Set up another pair X-Y for moving ports on node0.
 PortRef X, Y;
 EXPECT_EQ(OK, node0.node().CreatePortPair(&X, &Y));

 ScopedMessage message;

 // Move A to new port E.
 EXPECT_EQ(OK, node0.SendStringMessageWithPort(X, "foo", A));
 ASSERT_TRUE(node0.ReadMessage(Y, &message));
 ASSERT_EQ(1u, message->num_ports());
 PortRef E;
 ASSERT_EQ(OK, node0.node().GetPort(message->ports()[0], &E));

 EXPECT_EQ(OK, node0.node().ClosePort(X));
 EXPECT_EQ(OK, node0.node().ClosePort(Y));

 // Write messages on E and D.
 EXPECT_EQ(OK, node0.SendStringMessage(E, "hey"));
 EXPECT_EQ(OK, node1.SendStringMessage(D, "hi"));

 // Initiate a merge between B and C.
 node1.AllowPortMerge(C);
 EXPECT_EQ(OK, node0.node().MergePorts(B, node1.name(), C.name()));

 WaitForIdle();

 // Expect to receive D's message on E and E's message on D.
 ASSERT_TRUE(node0.ReadMessage(E, &message));
 EXPECT_TRUE(MessageEquals(message, "hi"));
 ASSERT_TRUE(node1.ReadMessage(D, &message));
 EXPECT_TRUE(MessageEquals(message, "hey"));

 // Close E and D.
 EXPECT_EQ(OK, node0.node().ClosePort(E));
 EXPECT_EQ(OK, node1.node().ClosePort(D));

 WaitForIdle();

 // Expect everything to have gone away.
 EXPECT_TRUE(node0.node().CanShutdownCleanly());
 EXPECT_TRUE(node1.node().CanShutdownCleanly());
}

TEST_F(PortsTest, MergePortsFailsGracefully) {
 // This tests that the system remains in a well-defined state if something
 // goes wrong during port merge.

 TestNode node0(0);
 AddNode(&node0);

 TestNode node1(1);
 AddNode(&node1);

 // Setup two independent port pairs, A-B on node0 and C-D on node1.
 PortRef A, B, C, D;
 EXPECT_EQ(OK, node0.node().CreatePortPair(&A, &B));
 EXPECT_EQ(OK, node1.node().CreatePortPair(&C, &D));

 ScopedMessage message;
 PortRef X, Y;
 EXPECT_EQ(OK, node0.node().CreateUninitializedPort(&X));
 EXPECT_EQ(OK, node1.node().CreateUninitializedPort(&Y));
 EXPECT_EQ(OK, node0.node().InitializePort(X, node1.name(), Y.name(),
                                           node1.name(), Y.name()));
 EXPECT_EQ(OK, node1.node().InitializePort(Y, node0.name(), X.name(),
                                           node0.name(), X.name()));

 // Block the merge from proceeding until we can do something stupid with port
 // C. This avoids the test logic racing with async merge logic.
 node1.BlockOnEvent(Event::Type::kMergePort);

 // Initiate the merge between B and C.
 node1.AllowPortMerge(C);
 EXPECT_EQ(OK, node0.node().MergePorts(B, node1.name(), C.name()));

 // Move C to a new port E. This is not a sane use of Node's public API but
 // is still hypothetically possible. It allows us to force a merge failure
 // because C will be in an invalid state by the time the merge is processed.
 // As a result, B should be closed.
 EXPECT_EQ(OK, node1.SendStringMessageWithPort(Y, "foo", C));

 node1.Unblock();

 WaitForIdle();

 ASSERT_TRUE(node0.ReadMessage(X, &message));
 ASSERT_EQ(1u, message->num_ports());
 PortRef E;
 ASSERT_EQ(OK, node0.node().GetPort(message->ports()[0], &E));

 EXPECT_EQ(OK, node0.node().ClosePort(X));
 EXPECT_EQ(OK, node1.node().ClosePort(Y));

 WaitForIdle();

 // C goes away as a result of normal proxy removal. B should have been closed
 // cleanly by the failed MergePorts.
 EXPECT_EQ(ERROR_PORT_UNKNOWN, node1.node().GetPort(C.name(), &C));
 EXPECT_EQ(ERROR_PORT_UNKNOWN, node0.node().GetPort(B.name(), &B));

 // Close A, D, and E.
 EXPECT_EQ(OK, node0.node().ClosePort(A));
 EXPECT_EQ(OK, node1.node().ClosePort(D));
 EXPECT_EQ(OK, node0.node().ClosePort(E));

 WaitForIdle();

 // Expect everything to have gone away.
 EXPECT_TRUE(node0.node().CanShutdownCleanly());
 EXPECT_TRUE(node1.node().CanShutdownCleanly());
}

TEST_F(PortsTest, RemotePeerStatus) {
 TestNode node0(0);
 AddNode(&node0);

 TestNode node1(1);
 AddNode(&node1);

 // Create a local port pair. Neither port should appear to have a remote peer.
 PortRef a, b;
 PortStatus status{};
 node0.node().CreatePortPair(&a, &b);
 ASSERT_EQ(OK, node0.node().GetStatus(a, &status));
 EXPECT_FALSE(status.peer_remote);
 ASSERT_EQ(OK, node0.node().GetStatus(b, &status));
 EXPECT_FALSE(status.peer_remote);

 // Create a port pair spanning the two nodes. Both spanning ports should
 // immediately appear to have a remote peer.
 PortRef x0, x1;
 CreatePortPair(&node0, &x0, &node1, &x1);

 ASSERT_EQ(OK, node0.node().GetStatus(x0, &status));
 EXPECT_TRUE(status.peer_remote);
 ASSERT_EQ(OK, node1.node().GetStatus(x1, &status));
 EXPECT_TRUE(status.peer_remote);

 PortRef x2, x3;
 CreatePortPair(&node0, &x2, &node1, &x3);

 // Transfer |b| to |node1| and |x1| to |node0|. i.e., make the local peers
 // remote and the remote peers local.
 EXPECT_EQ(OK, node0.SendStringMessageWithPort(x2, "foo", b));
 EXPECT_EQ(OK, node1.SendStringMessageWithPort(x3, "bar", x1));
 WaitForIdle();

 ScopedMessage message;
 ASSERT_TRUE(node0.ReadMessage(x2, &message));
 ASSERT_EQ(1u, message->num_ports());
 ASSERT_EQ(OK, node0.node().GetPort(message->ports()[0], &x1));

 ASSERT_TRUE(node1.ReadMessage(x3, &message));
 ASSERT_EQ(1u, message->num_ports());
 ASSERT_EQ(OK, node1.node().GetPort(message->ports()[0], &b));

 // Now x0-x1 should be local to node0 and a-b should span the nodes.
 ASSERT_EQ(OK, node0.node().GetStatus(x0, &status));
 EXPECT_FALSE(status.peer_remote);
 ASSERT_EQ(OK, node0.node().GetStatus(x1, &status));
 EXPECT_FALSE(status.peer_remote);
 ASSERT_EQ(OK, node0.node().GetStatus(a, &status));
 EXPECT_TRUE(status.peer_remote);
 ASSERT_EQ(OK, node1.node().GetStatus(b, &status));
 EXPECT_TRUE(status.peer_remote);

 // And swap them back one more time.
 EXPECT_EQ(OK, node0.SendStringMessageWithPort(x2, "foo", x1));
 EXPECT_EQ(OK, node1.SendStringMessageWithPort(x3, "bar", b));
 WaitForIdle();

 ASSERT_TRUE(node0.ReadMessage(x2, &message));
 ASSERT_EQ(1u, message->num_ports());
 ASSERT_EQ(OK, node0.node().GetPort(message->ports()[0], &b));

 ASSERT_TRUE(node1.ReadMessage(x3, &message));
 ASSERT_EQ(1u, message->num_ports());
 ASSERT_EQ(OK, node1.node().GetPort(message->ports()[0], &x1));

 ASSERT_EQ(OK, node0.node().GetStatus(x0, &status));
 EXPECT_TRUE(status.peer_remote);
 ASSERT_EQ(OK, node1.node().GetStatus(x1, &status));
 EXPECT_TRUE(status.peer_remote);
 ASSERT_EQ(OK, node0.node().GetStatus(a, &status));
 EXPECT_FALSE(status.peer_remote);
 ASSERT_EQ(OK, node0.node().GetStatus(b, &status));
 EXPECT_FALSE(status.peer_remote);

 EXPECT_EQ(OK, node0.node().ClosePort(x0));
 EXPECT_EQ(OK, node1.node().ClosePort(x1));
 EXPECT_EQ(OK, node0.node().ClosePort(x2));
 EXPECT_EQ(OK, node1.node().ClosePort(x3));
 EXPECT_EQ(OK, node0.node().ClosePort(a));
 EXPECT_EQ(OK, node0.node().ClosePort(b));

 EXPECT_TRUE(node0.node().CanShutdownCleanly());
 EXPECT_TRUE(node1.node().CanShutdownCleanly());
}

TEST_F(PortsTest, RemotePeerStatusAfterLocalPortMerge) {
 TestNode node0(0);
 AddNode(&node0);

 TestNode node1(1);
 AddNode(&node1);

 // Set up a-b on node0 and c-d spanning node0-node1.
 PortRef a, b, c, d;
 node0.node().CreatePortPair(&a, &b);
 CreatePortPair(&node0, &c, &node1, &d);

 PortStatus status{};
 ASSERT_EQ(OK, node0.node().GetStatus(a, &status));
 EXPECT_FALSE(status.peer_remote);
 ASSERT_EQ(OK, node0.node().GetStatus(b, &status));
 EXPECT_FALSE(status.peer_remote);
 ASSERT_EQ(OK, node0.node().GetStatus(c, &status));
 EXPECT_TRUE(status.peer_remote);
 ASSERT_EQ(OK, node1.node().GetStatus(d, &status));
 EXPECT_TRUE(status.peer_remote);

 EXPECT_EQ(OK, node0.node().MergeLocalPorts(b, c));
 WaitForIdle();

 ASSERT_EQ(OK, node0.node().GetStatus(a, &status));
 EXPECT_TRUE(status.peer_remote);
 ASSERT_EQ(OK, node1.node().GetStatus(d, &status));
 EXPECT_TRUE(status.peer_remote);

 EXPECT_EQ(OK, node0.node().ClosePort(a));
 EXPECT_EQ(OK, node1.node().ClosePort(d));
 EXPECT_TRUE(node0.node().CanShutdownCleanly());
 EXPECT_TRUE(node1.node().CanShutdownCleanly());
}

TEST_F(PortsTest, RemotePeerStatusAfterRemotePortMerge) {
 TestNode node0(0);
 AddNode(&node0);

 TestNode node1(1);
 AddNode(&node1);

 // Set up a-b on node0 and c-d on node1.
 PortRef a, b, c, d;
 node0.node().CreatePortPair(&a, &b);
 node1.node().CreatePortPair(&c, &d);

 PortStatus status{};
 ASSERT_EQ(OK, node0.node().GetStatus(a, &status));
 EXPECT_FALSE(status.peer_remote);
 ASSERT_EQ(OK, node0.node().GetStatus(b, &status));
 EXPECT_FALSE(status.peer_remote);
 ASSERT_EQ(OK, node1.node().GetStatus(c, &status));
 EXPECT_FALSE(status.peer_remote);
 ASSERT_EQ(OK, node1.node().GetStatus(d, &status));
 EXPECT_FALSE(status.peer_remote);

 node1.AllowPortMerge(c);
 EXPECT_EQ(OK, node0.node().MergePorts(b, node1.name(), c.name()));
 WaitForIdle();

 ASSERT_EQ(OK, node0.node().GetStatus(a, &status));
 EXPECT_TRUE(status.peer_remote);
 ASSERT_EQ(OK, node1.node().GetStatus(d, &status));
 EXPECT_TRUE(status.peer_remote);

 EXPECT_EQ(OK, node0.node().ClosePort(a));
 EXPECT_EQ(OK, node1.node().ClosePort(d));
 EXPECT_TRUE(node0.node().CanShutdownCleanly());
 EXPECT_TRUE(node1.node().CanShutdownCleanly());
}

TEST_F(PortsTest, RetransmitUserMessageEvents) {
 // Ensures that user message events can be retransmitted properly.
 TestNode node0(0);
 AddNode(&node0);

 PortRef a, b;
 node0.node().CreatePortPair(&a, &b);

 // Ping.
 const char* kMessage = "hey";
 ScopedMessage message;
 EXPECT_EQ(OK, node0.SendStringMessage(a, kMessage));
 ASSERT_TRUE(node0.ReadMessage(b, &message));
 EXPECT_TRUE(MessageEquals(message, kMessage));

 // Pong.
 EXPECT_EQ(OK, node0.node().SendUserMessage(b, std::move(message)));
 EXPECT_FALSE(message);
 ASSERT_TRUE(node0.ReadMessage(a, &message));
 EXPECT_TRUE(MessageEquals(message, kMessage));

 // Ping again.
 EXPECT_EQ(OK, node0.node().SendUserMessage(a, std::move(message)));
 EXPECT_FALSE(message);
 ASSERT_TRUE(node0.ReadMessage(b, &message));
 EXPECT_TRUE(MessageEquals(message, kMessage));

 // Pong again!
 EXPECT_EQ(OK, node0.node().SendUserMessage(b, std::move(message)));
 EXPECT_FALSE(message);
 ASSERT_TRUE(node0.ReadMessage(a, &message));
 EXPECT_TRUE(MessageEquals(message, kMessage));

 EXPECT_EQ(OK, node0.node().ClosePort(a));
 EXPECT_EQ(OK, node0.node().ClosePort(b));
}

TEST_F(PortsTest, SetAcknowledgeRequestInterval) {
 TestNode node0(0);
 AddNode(&node0);

 PortRef a0, a1;
 EXPECT_EQ(OK, node0.node().CreatePortPair(&a0, &a1));
 EXPECT_EQ(0u, node0.GetUnacknowledgedMessageCount(a0));

 // Send a batch of messages.
 EXPECT_EQ(OK, node0.SendMultipleMessages(a0, 15));
 EXPECT_EQ(15u, node0.GetUnacknowledgedMessageCount(a0));
 EXPECT_TRUE(node0.ReadMultipleMessages(a1, 5));
 WaitForIdle();
 EXPECT_EQ(15u, node0.GetUnacknowledgedMessageCount(a0));

 // Set to acknowledge every read message, and validate that already-read
 // messages are acknowledged.
 EXPECT_EQ(OK, node0.node().SetAcknowledgeRequestInterval(a0, 1));
 WaitForIdle();
 EXPECT_EQ(10u, node0.GetUnacknowledgedMessageCount(a0));

 // Read a third of the messages from the other end.
 EXPECT_TRUE(node0.ReadMultipleMessages(a1, 5));
 WaitForIdle();

 EXPECT_EQ(5u, node0.GetUnacknowledgedMessageCount(a0));

 TestNode node1(1);
 AddNode(&node1);

 // Transfer a1 across to node1.
 PortRef x0, x1;
 CreatePortPair(&node0, &x0, &node1, &x1);
 EXPECT_EQ(OK, node0.SendStringMessageWithPort(x0, "foo", a1));
 WaitForIdle();

 ScopedMessage message;
 ASSERT_TRUE(node1.ReadMessage(x1, &message));
 ASSERT_EQ(1u, message->num_ports());
 ASSERT_EQ(OK, node1.node().GetPort(message->ports()[0], &a1));

 // Read the last third of the messages from the transferred node, and
 // validate that the unacknowledge message count updates correctly.
 EXPECT_TRUE(node1.ReadMultipleMessages(a1, 5));
 WaitForIdle();
 EXPECT_EQ(0u, node0.GetUnacknowledgedMessageCount(a0));

 // Turn the acknowledges down and validate that they don't go on indefinitely.
 EXPECT_EQ(OK, node0.node().SetAcknowledgeRequestInterval(a0, 0));
 EXPECT_EQ(OK, node0.SendMultipleMessages(a0, 10));
 WaitForIdle();
 EXPECT_TRUE(node1.ReadMultipleMessages(a1, 10));
 WaitForIdle();
 EXPECT_NE(0u, node0.GetUnacknowledgedMessageCount(a0));

 // Close the far port and validate that the closure updates the unacknowledged
 // count.
 EXPECT_EQ(OK, node1.node().ClosePort(a1));
 WaitForIdle();
 EXPECT_EQ(0u, node0.GetUnacknowledgedMessageCount(a0));

 EXPECT_EQ(OK, node0.node().ClosePort(a0));
 EXPECT_EQ(OK, node0.node().ClosePort(x0));
 EXPECT_EQ(OK, node1.node().ClosePort(x1));
}

}  // namespace test
}  // namespace ports
}  // namespace core
}  // namespace mojo