GoogleTest Expect call fail for the mock method

c++, googlemock, googletest, mocking, unit-testing

Solution

There are two bugs in your code, meaning you are lacking c++ basics.

The first bug is in your mock class. The `GetSize()` method in base class `Foo` is declared as : `virtual int GetSize(int size)` but in your mock it is : `MOCK_CONST_METHOD1(GetSize, int(int size));` meaning `virtual int GetSize(int size) const` These two methods have different signatures, and because of that, MockFoo is not overriding the Foo's method.

The second bug is when you pass MockFoo's object into DisplayFoo's constructor. What I think you wanted to do is to use MockFoo object, but you accidentally copied it's base object. Changing FooDisplay to this should solve this issue :

class FooDisplay {
public:
    FooDisplay (Foo & _foo) : foo (_foo) { }
    virtual ~FooDisplay () { }

    virtual std::string Describe (int size) {
        foo.GetSize (size);
        std::string str = "Done";
        return str;
    }

    private:
        Foo & foo;
};

Problem

I am new to the GTEST, just understanding the how the Mock works, i tried to write the simple program Foo.h and FooDisplay.h ( which needs the Foo in the constructor), also MockFoo.cpp ( which is the main GTEST program to test the Gmock).. when i mock and do the Expect call for the Foo, it throws below in the execution.. Logs ``` [==========] Running 1 test from 1 test case. [----------] Global test environment set-up. [----------] 1 test from Foo [ RUN ] Foo.case1 package/web/webscr/MockFoo.cpp:19: Failure Actual function call count doesn't match EXPECT_CALL(mock, GetSize(_))... Expected: to be called once Actual: never called - unsatisfied and active [ FAILED ] Foo.case1 (0 ms) [----------] 1 test from Foo (0 ms total) [----------] Global test environment tear-down [==========] 1 test from 1 test case ran. (0 ms total) [ PASSED ] 0 tests. [ FAILED ] 1 test, listed below: [ FAILED ] Foo.case1 ``` Foo.h ``` #include <gtest/gtest.h> #include <infra/utility/core/lang/PPException.h> #include <infra/utility/core/lang/String.h> #include <iostream> class Foo { public: virtual ~Foo() { } virtual int GetSize(int size) { return size; } }; ``` FooDisplay.h ``` #include <gtest/gtest.h> #include <infra/utility/core/lang/PPException.h> #include <infra/utility/core/lang/String.h> #include <iostream> #include "Foo.h" class FooDisplay { public: FooDisplay ( Foo _foo) : foo(_foo) { } virtual ~FooDisplay() { } virtual String Describe(int size) { foo.GetSize(size); String str = "Done"; return str; } private: Foo foo; }; ``` MooFoo.cpp ``` #include "gmock/gmock.h" #include <infra/utility/core/lang/String.h> #include <iostream> #include "FooDisplay.h" using ::testing::Return; using ::testing::_; class MockFoo : public Foo { public: MOCK_CONST_METHOD1(GetSize, int(int size)); //MOCK_CONST_METHOD1(Describe, String(int)); }; TEST(Foo,case1) { MockFoo mockfoo; FooDisplay Display(mockfoo); EXPECT_CALL(mockfoo,GetSize(_)).WillOnce(Return(6)); Display.Describe(5); // ON_CALL(Display,Describe(5)).WillByDefault( Return ("Hi")); } int main(int argc, char * argv[]) { ::testing::InitGoogleTest(&argc,argv); return RUN_ALL_TESTS(); //return 1; } ```

Original source