I asked Google for an example for a GTest MOCK_METHOD() usage. It gave me this:
/
/ 1. The Interface (the class you want to mock)
class Database {
public:
virtual ~Database() {}
virtual bool Open(const std::string& connection_string) = 0;
virtual int GetCount() const = 0;
};
// 2. The Mock Class
class MockDatabase : public Database {
public:
// MOCK_METHOD(ReturnType, MethodName, (Args), (Specifiers))
MOCK_METHOD(bool, Open, (const std::string& connection_string), (override));
MOCK_METHOD(int, GetCount, (), (const, override));
};
// 3. The Test
TEST(DatabaseTest, CanOpenConnection) {
MockDatabase mock_db;
// Set expectations: Expect Open() to be called once with "prod_db" and return true
EXPECT_CALL(mock_db, Open("prod_db"))
.Times(1)
.WillOnce(testing::Return(true));
// Exercise the code
bool result = mock_db.Open("prod_db");
// Verify
EXPECT_TRUE(result);
}
It seems to me that this test doesn’t do anything at all except to verify that the mock method works as expected. Is this as silly as I think it is, or is this really something an experienced tester would write?
I think a mock should be something that a method being tested uses. So, I would use this mock method to verify that my production code proceeds correctly after the Open() call succeeds, and then I would set up the mock to return a failure and verify that my code proceeds as expected after the failure.