googlemock matcher for output parameters

Question

I am testing whether my class calls a method on a mocked class, with the proper argument. I have set up a basic expectation:

// mListener is a mocked object
// This expectation accepts any argument
EXPECT_CALL(this->mListener, OnChanged(_))
    .Times(1);

This is fine, but I also want to verify the argument. It is an object which only has accessors that use output parameters:

// aValue is an output parameter
HRESULT get_Value(int* aValue);

How can I define a matcher that will inspect the value that get_Value puts into aValue?

Answer 1

You could try something like:

MATCHER_P(CheckValue,
          expected_value,
          std::string("get_Value ")
              + (negation ? "yields " : "doesn't yield ")
              + PrintToString(expected_value)
              + " as expected.") {
  int result;
  arg.get_Value(&result);
  return expected_value == result;
}

which could check that e.g. aValue == 7 by doing:

EXPECT_CALL(this->mListener, OnChanged(CheckValue(7)))
    .Times(1);