Minor improvements to MockLogDnsTraffic

components/certificate_transparency/mock_log_dns_traffic.h

 // 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.
 
 #ifndef COMPONENTS_CERTIFICATE_TRANSPARENCY_MOCK_LOG_DNS_TRAFFIC_H_
 #define COMPONENTS_CERTIFICATE_TRANSPARENCY_MOCK_LOG_DNS_TRAFFIC_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 57 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(MockSocketData);
 };
 
 }  // namespace internal
 
 // Mocks DNS requests and responses for a Certificate Transparency (CT) log.
 // This is implemented using mock sockets. Call the CreateDnsClient() method to
 // get a net::DnsClient wired up to these mock sockets.
 // The Expect*() methods must be called from within a GTest test case.
+//
+// Example Usage:
+// // Create a mock NetworkChangeNotifier to propogate DNS config.
+// std::unique_ptr<net::NetworkChangeNotifier> net_change_notifier =
+//     net::NetworkChangeNotifier::CreateMock();
+//
+// MockLogDnsTraffic mock_dns;
+// mock_dns.InitializeDnsConfig();
+// // Use the Expect* methods to define expected DNS requests and responses.
+// mock_dns.ExpectLeafIndexRequestAndResponse(
+//     "D4S6DSV2J743QJZEQMH4UYHEYK7KRQ5JIQOCPMFUHZVJNFGHXACA.hash.ct.test.",
+//     "123456");
+//
+// LogDnsClient log_client(mock_dns.CreateDnsClient(), ...);
+// log_client.QueryLeafIndex("ct.test", ...);

[Eran Messeri, 2016/09/20 14:31:04]

Which message loop should be pumped to guarantee the callback has been invoked?

[Rob Percival, 2016/09/20 16:33:11]

I've added a few more lines to the example usage to show that a
MessageLoopWithIO should be used.

 class MockLogDnsTraffic {
  public:
   MockLogDnsTraffic();
   ~MockLogDnsTraffic();
 
   // Expect a CT DNS request for the domain |qname|.
   // Such a request will receive a DNS response indicating that the error
   // specified by |rcode| occurred. See RFC1035, Section 4.1.1 for |rcode|
   // values.
   void ExpectRequestAndErrorResponse(base::StringPiece qname, uint8_t rcode);
@@ skipping 31 matching lines @@
   // Requires that net::NetworkChangeNotifier is initialized first.
   // The DNS config is propogated to NetworkChangeNotifier::DNSObservers
   // asynchronously.
   void SetDnsConfig(const net::DnsConfig& config);
 
   // Creates a DNS client that uses mock sockets.
   // It is this DNS client that the expectations will be tested against.
   std::unique_ptr<net::DnsClient> CreateDnsClient();
 
   // Sets whether mock reads should complete synchronously or asynchronously.
+  // By default, they complete asynchronously. The only reason to change this
+  // is to test that LogDnsClient handles both modes in the same way.
   void SetSocketReadMode(net::IoMode read_mode) {
     socket_read_mode_ = read_mode;
   }
 
  private:
   // Expect A CT DNS request for the domain |qname|.
   // Such a request will receive a DNS response containing |answer|.
   void ExpectRequestAndResponse(base::StringPiece qname,
                                 base::StringPiece answer);
 
@@ skipping 14 matching lines @@
   net::MockClientSocketFactory socket_factory_;
   // Controls whether mock socket reads are asynchronous.
   net::IoMode socket_read_mode_;
 
   DISALLOW_COPY_AND_ASSIGN(MockLogDnsTraffic);
 };
 
 }  // namespace certificate_transparency
 
 #endif  // COMPONENTS_CERTIFICATE_TRANSPARENCY_MOCK_LOG_DNS_TRAFFIC_H_