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      1 //
      2 // Copyright (C) 2012 The Android Open Source Project
      3 //
      4 // Licensed under the Apache License, Version 2.0 (the "License");
      5 // you may not use this file except in compliance with the License.
      6 // You may obtain a copy of the License at
      7 //
      8 //      http://www.apache.org/licenses/LICENSE-2.0
      9 //
     10 // Unless required by applicable law or agreed to in writing, software
     11 // distributed under the License is distributed on an "AS IS" BASIS,
     12 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13 // See the License for the specific language governing permissions and
     14 // limitations under the License.
     15 //
     16 
     17 #ifndef SHILL_MOCK_LOG_H_
     18 #define SHILL_MOCK_LOG_H_
     19 
     20 // ScopedMockLog provides a way for unittests to validate log messages.  You can
     21 // set expectations that certain log messages will be emited by your functions.
     22 // To use ScopedMockLog, simply create a ScopedMockLog in your test and set
     23 // expectations on its Log() method.  When the ScopedMockLog object goes out of
     24 // scope, the log messages sent to it will be verified against expectations.
     25 //
     26 // Note: Use only one ScopedMockLog in a test because more than one won't work!
     27 //
     28 // Sample usage:
     29 //
     30 // You can verify that a function "DoSomething" emits a specific log text:
     31 //
     32 //   TEST_F(YourTest, DoesSomething) {
     33 //     ScopedMockLog log;
     34 //     EXPECT_CALL(log, Log(_, _, "Some log message text"));
     35 //     DoSomething();  // Causes "Some log message text" to be logged.
     36 //   }
     37 //
     38 // If the function DoSomething() executes something like:
     39 //
     40 //   LOG(INFO) << "Some log message text";
     41 //
     42 // then this will match the expectation.
     43 //
     44 // The first two parameters to ScopedMockLog::Log are the log severity and
     45 // filename.  You can use them like this:
     46 //
     47 //   TEST_F(MockLogTest, MockLogSeverityAndFileAndMessage) {
     48 //     ScopedMockLog log;
     49 //     EXPECT_CALL(log, Log(logging::LOG_INFO, "your_file.cc", "your message"));
     50 //     DoSomething();
     51 //   }
     52 //
     53 // You can also use gMock matchers for matching arguments to Log():
     54 //
     55 //   TEST_F(MockLogTest, MatchWithGmockMatchers) {
     56 //     ScopedMockLog log;
     57 //     EXPECT_CALL(log, Log(::testing::Lt(::logging::LOG_ERROR),
     58 //                          ::testing::EndsWith(".cc"),
     59 //                          ::testing::StartsWith("Some")));
     60 //     DoSomething();
     61 //   }
     62 //
     63 // For some examples, see mock_log_unittest.cc.
     64 
     65 #include <string>
     66 #include <gmock/gmock.h>
     67 
     68 #include "shill/logging.h"
     69 
     70 namespace shill {
     71 
     72 class ScopedMockLog {
     73  public:
     74   ScopedMockLog();
     75   virtual ~ScopedMockLog();
     76 
     77   // Users set expecations on this method.  |severity| is defined in
     78   // base/logging.h, like logging:::LOG_INFO.  |file| is the filename which
     79   // issues the log message, like "foo.cc".  |user_messages| is the message you
     80   // expect to see.  Arguments can be ignored by specifying ::testing::_.  You
     81   // can also specify gMock matchers for arguments.
     82   MOCK_METHOD3(Log, void(int severity, const char* file,
     83                          const std::string& user_message));
     84 
     85  private:
     86   // This function gets invoked by the logging subsystem for each message that
     87   // is logged.  It calls ScopedMockLog::Log() declared above.  It must be a
     88   // static method because the logging subsystem does not allow for an object to
     89   // be passed.  See the typedef LogMessageHandlerFunction in base/logging.h for
     90   // this function signature.
     91   static bool HandleLogMessages(int severity,
     92                                 const char* file,
     93                                 int line,
     94                                 size_t message_start,
     95                                 const std::string& full_message);
     96 
     97   // A pointer to the current ScopedMockLog object.
     98   static ScopedMockLog* instance_;
     99 
    100   // A pointer to any pre-existing message hander function in the logging
    101   // system.  It is invoked after calling ScopedMockLog::Log().
    102   ::logging::LogMessageHandlerFunction previous_handler_;
    103 };
    104 
    105 // A NiceScopedMockLog is the same as ScopedMockLog, except it creates an
    106 // implicit expectation on any Log() call.  This allows tests to avoid having
    107 // to explictly expect log messages they don't care about.
    108 class NiceScopedMockLog : public ScopedMockLog {
    109  public:
    110   NiceScopedMockLog();
    111   ~NiceScopedMockLog() override;
    112 };
    113 
    114 }  // namespace shill
    115 
    116 #endif  // SHILL_MOCK_LOG_H_
    117