How to capture stdout/stderr with googletest?

Question

Is it possible to capture the stdout and stderr when using the googletest framework?

For example, I would like to call a function that writes errors to the console (

Answer 1

We are doing exactly what you are referring to.

First we created some macros:

    #define CAPTURE_STDOUT StdoutRedirect::instance().redirect();
    #define RELEASE_STDOUT StdoutRedirect::instance().reset();
    #define ASSERT_INFO( COUNT, TARGET )   \
      ASSERT_PRED_FORMAT2(OurTestPredicates::AssertInfoMsgOutput, TARGET, COUNT );

See this answer for capturing stdout and stderr: https://stackoverflow.com/a/5419409/9796918 Just use their BeginCapture(), EndCapture() in place of our redirect() and reset().

In the AssertInfoMsgOutput method:

    AssertionResult OurTestPredicates::AssertInfoMsgOutput( const char* TARGET,
        const char* d1,
        const char* d2,
        int         COUNT )
    {
      int count = 0;
      bool match = false;
      std::string StdOutMessagge = GetCapture();
      // Here is where you process the stdout/stderr info for the TARGET, and for
      // COUNT instances of that TARGET message, and set count and match
      // appropriately
      ...
      if (( count == COUNT ) && match )
      {
        return ::testing::AssertionSuccess();
      }
      return :: testing::AssertionFailure() << "not found";
    }

Now in your unit test just wrap your calls that you want to capture stdout/stderr with:

    CAPTURE_STDOUT
    // Make your call to your code to test / capture here
    ASSERT_INFO( 1, "Foo bar" );
    RELEASE_STDOUT