Matching std::wstring in googlemocks EXPECT_CALL

Question

I have the mocked interface

// Interface
class MyInterface
{
    void get(const std::wstring& param) = 0;
}

// Mock interface
class MyInterfaceMock : public MyInterface
{
    MOCK_METHOD1(get, void(const std::wstring& param));
}

Exemplaric test method:

...
EXPECT_CALL(myInterfaceMock, L"hello");

When I compile it (vs2015) I get the message

error C2664: 'testing::internal::MockSpec...: cannot convert argument 1 from 'const wchar_t [6]' to 'const testing::Matcher &'

followed by the message: Reason: cannot convert from 'const wchar_t [7]' to 'const testing::Matcher'

When I use std::string instead std::wstring the everything works fine. Does anybody know why the std::wstring cannot be matched?

Answer 1

I guess you meant EXPECT_CALL(myInterfaceMock, get(L"hello"));

You should write EXPECT_CALL(myInterfaceMock, get(std::wstring(L"hello"))); everything should work.

The real question is why matcher from std::string accepts const char* as value. The answer is - because google-mock library supported this by intention - see code:

template <>
class GTEST_API_ Matcher<std::string>
    : public internal::MatcherBase<std::string> {
 public:
  Matcher() {}

  explicit Matcher(const MatcherInterface<const std::string&>* impl)
      : internal::MatcherBase<std::string>(impl) {}
  explicit Matcher(const MatcherInterface<std::string>* impl)
      : internal::MatcherBase<std::string>(impl) {}

  template <typename M, typename = typename std::remove_reference<
                            M>::type::is_gtest_matcher>
  Matcher(M&& m)  // NOLINT
      : internal::MatcherBase<std::string>(std::forward<M>(m)) {}

  // Allows the user to write str instead of Eq(str) sometimes, where
  // str is a string object.
  Matcher(const std::string& s);  // NOLINT

  // Allows the user to write "foo" instead of Eq("foo") sometimes.
  Matcher(const char* s);  // NOLINT
};

There is no equivalent specialization of Matcher<T> for std::wstring. I advice you do not add one - because it might change in future - this is gmock implementation detail. Instead you might ask gmock developers to add support for wstring in the similar way as for string... BTW, I already addeded one.