Actual function call count doesn't match EXPECT_CALL(*mock, display())

Question

I'm calling EXPECT_CALL on a mocked function display(), but it is returning the run time error

Actual function call count doesn't match EXPECT_CALL(*mock, display())...

output

./GTest_static_example.tst

[==========] Running 1 test from 1 test case.
[----------] Global test environment set-up.
[----------] 1 test from GTest_static_example
[ RUN      ] GTest_static_example.case1
inside the GTEST_static_class:: display
display called from GTest_static_example
package/web/webscr/GTest_static_example.cpp:70: Failure
Actual function call count doesn't match EXPECT_CALL(*mock, display())...
         Expected: to be called once
           Actual: never called - unsatisfied and active
[  FAILED  ] GTest_static_example.case1 (0 ms)
[----------] 1 test from GTest_static_example (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  ] GTest_static_example.case1

 1 FAILED TEST

GTEST_static_class.h

#include<iostream>

using namespace std;
class GTEST_static_class
{   
    public:
    GTEST_static_class()
    {}

    void display()
    {
        cout<< "inside the GTEST_static_class:: display " <<endl;
    } 
};

GTest_static_example.cpp

#include <gtest/gtest.h>
#include <gmock/gmock.h>
#include <iostream>
#include "GTEST_static_class.h"

using namespace std;
using ::testing::Return;


class GTest_static_example : public::testing::Test
{
    public:
    virtual void SetUp();
    virtual void TearDown();
    void call_display()
    {
        GTEST_static_class *_class = new GTEST_static_class();
        _class->display();
        cout<<"display called from GTest_static_example"<<endl;
    }

};


class MockGTEST_static_class : public GTEST_static_class
{
    public:
    MockGTEST_static_class():GTEST_static_class()
    {}

    MOCK_METHOD0(display, void()); 
};


int main(int argc, char* argv[])
{
    ::testing::InitGoogleTest(&argc, argv);
    return RUN_ALL_TESTS();
}

void GTest_static_example::SetUp()
{}

void GTest_static_example::TearDown()
{}

TEST_F(GTest_static_example, case1)
{
    MockGTEST_static_class *mock = new MockGTEST_static_class();
    EXPECT_CALL(*mock,display()).WillOnce(Return());
    call_display();
    delete mock;
}

Answer 1

Try something more like:

#include <iostream>
#include <gtest/gtest.h>
#include <gmock/gmock.h>

class GTEST_static_class {
  public:
    virtual void display() { std::cout << "inside the GTEST_static_class:: display\n"; }
    virtual ~GTEST_static_class() {}
};

class MockGTEST_static_class : public GTEST_static_class {
  public:
    MOCK_METHOD0(display, void());
};

class GTest_static_example : public ::testing::Test {
  public:
    void call_display(GTEST_static_class *instance) {
      instance->display();
      std::cout << "display called from GTest_static_example\n";
    }
};

int main(int argc, char * argv[]) {
  ::testing::InitGoogleTest(&argc,argv);
  return RUN_ALL_TESTS();
}

TEST_F(GTest_static_example, case1) {
  MockGTEST_static_class mock;
  EXPECT_CALL(mock, display()).WillOnce(::testing::Return());
  call_display(&mock);
}

You need to pass the actual instance of the class upon which you make the expectation. Also, you need to make void display(); virtual if you want the mock to be able to override it. Forgetting to add virtual unfortunately doesn't generate any compiler warnings or errors - it' just something you have to watch out for. You should also make GTEST_static_class's destructor virtual to avoid slicing.