Give MockRead and MockWrite distinct types.

net/socket/socket_test_util.h

Index: net/socket/socket_test_util.h
diff --git a/net/socket/socket_test_util.h b/net/socket/socket_test_util.h
index 171e3c3d2e536d4cbc3878e9c57d2de837c7d72a..70876400d4a26eaec2cbcbb84422ac1bd5b0d211 100644
--- a/net/socket/socket_test_util.h
+++ b/net/socket/socket_test_util.h
@@ -72,48 +72,65 @@ struct MockConnect {
   IPEndPoint peer_addr;
 };
 
-struct MockRead {
+// MockRead and MockWrite shares the same interface and members, but we'd like
+// to have distinct types because we don't want to have them used
+// interchangably. To do this, a struct template is defined, and MockRead and
+// MockWrite are instantiated by using this template. Template parameter |type|
+// is not used in the struct definition (it purely exists for creating a new
+// type).
+//
+// |data| in MockRead and MockWrite has different meanings: |data| in MockRead
+// is the data returned from the socket when MockTCPClientSocket::Read() is
+// attempted, while |data| in MockWrite is the expected data that should be
+// given in MockTCPClientSocket::Write().
+enum MockReadWriteType {
+  MOCK_READ,
+  MOCK_WRITE
+};
+
+template <MockReadWriteType type>
+struct MockReadWrite {
   // Flag to indicate that the message loop should be terminated.
   enum {
     STOPLOOP = 1 << 31
   };
 
   // Default
-  MockRead() : mode(SYNCHRONOUS), result(0), data(NULL), data_len(0),
+  MockReadWrite() : mode(SYNCHRONOUS), result(0), data(NULL), data_len(0),
       sequence_number(0), time_stamp(base::Time::Now()) {}
 
-  // Read failure (no data).
-  MockRead(IoMode io_mode, int result) : mode(io_mode), result(result),
+  // Read/write failure (no data).
+  MockReadWrite(IoMode io_mode, int result) : mode(io_mode), result(result),
       data(NULL), data_len(0), sequence_number(0),
       time_stamp(base::Time::Now()) { }
 
-  // Read failure (no data), with sequence information.
-  MockRead(IoMode io_mode, int result, int seq) : mode(io_mode),
+  // Read/write failure (no data), with sequence information.
+  MockReadWrite(IoMode io_mode, int result, int seq) : mode(io_mode),
       result(result), data(NULL), data_len(0), sequence_number(seq),
       time_stamp(base::Time::Now()) { }
 
-  // Asynchronous read success (inferred data length).
-  explicit MockRead(const char* data) : mode(ASYNC),  result(0), data(data),
-      data_len(strlen(data)), sequence_number(0),
+  // Asynchronous read/write success (inferred data length).
+  explicit MockReadWrite(const char* data) : mode(ASYNC),  result(0),
+      data(data), data_len(strlen(data)), sequence_number(0),
       time_stamp(base::Time::Now()) { }
 
-  // Read success (inferred data length).
-  MockRead(IoMode io_mode, const char* data) : mode(io_mode), result(0),
+  // Read/write success (inferred data length).
+  MockReadWrite(IoMode io_mode, const char* data) : mode(io_mode), result(0),
       data(data), data_len(strlen(data)), sequence_number(0),
       time_stamp(base::Time::Now()) { }
 
-  // Read success.
-  MockRead(IoMode io_mode, const char* data, int data_len) : mode(io_mode),
+  // Read/write success.
+  MockReadWrite(IoMode io_mode, const char* data, int data_len) : mode(io_mode),
       result(0), data(data), data_len(data_len), sequence_number(0),
       time_stamp(base::Time::Now()) { }
 
-  // Read success (inferred data length) with sequence information.
-  MockRead(IoMode io_mode, int seq, const char* data) : mode(io_mode),
+  // Read/write success (inferred data length) with sequence information.
+  MockReadWrite(IoMode io_mode, int seq, const char* data) : mode(io_mode),
       result(0), data(data), data_len(strlen(data)), sequence_number(seq),
       time_stamp(base::Time::Now()) { }
 
-  // Read success with sequence information.
-  MockRead(IoMode io_mode, const char* data, int data_len, int seq) :
+  // Read/write success with sequence information.
+  MockReadWrite(IoMode io_mode, const char* data, int data_len, int seq) :
       mode(io_mode), result(0), data(data), data_len(data_len),
       sequence_number(seq), time_stamp(base::Time::Now()) { }
 
@@ -130,11 +147,8 @@ struct MockRead {
   base::Time time_stamp;    // The time stamp at which the operation occurred.
 };
 
-// MockWrite uses the same member fields as MockRead, but with different
-// meanings. The expected input to MockTCPClientSocket::Write() is given
-// by {data, data_len}, and the return value of Write() is controlled by
-// {async, result}.
-typedef MockRead MockWrite;
+typedef MockReadWrite<MOCK_READ> MockRead;
+typedef MockReadWrite<MOCK_WRITE> MockWrite;
 
 struct MockWriteResult {
   MockWriteResult(IoMode io_mode, int result)
@@ -461,7 +475,7 @@ class DeterministicSocketData
   bool stopped() const { return stopped_; }
   void SetStopped(bool val) { stopped_ = val; }
   MockRead& current_read() { return current_read_; }
-  MockRead& current_write() { return current_write_; }
+  MockWrite& current_write() { return current_write_; }
   int sequence_number() const { return sequence_number_; }
   void set_socket(base::WeakPtr<DeterministicMockTCPClientSocket> socket) {
     socket_ = socket;