How to specify consecutive returns in gmock?

Question

In Mockito we can specify multiple returns like (taken from here):

//you can set different behavior for consecutive method calls.
 //Last stubbing (e.g: thenReturn("foo")) determines the behavior of further consecutive calls.
 when(mock.someMethod("some arg"))
  .thenReturn(new RuntimeException())
  .thenReturn("foo");

 //There is a shorter way of consecutive stubbing:
 when(mock.someMethod()).thenReturn(1,2,3);
 when(mock.otherMethod()).thenThrow(exc1, exc2);

Is there a way to specify multiple returns for a mock made with gmock? Currently I have:

store_mock_ = std::make_shared<StorageMock>();
ON_CALL(*store_mock_, getFileName(_)).Return("file1").Return("file2");

which doesn't compile because I can't figure out multiple returns in gmock. Is this possible with gmock? If not, is there another way to solve this problem? I've found that we can EXPECT multiple return values like:

using ::testing::Return;...
EXPECT_CALL(turtle, GetX())
    .WillOnce(Return(100))
    .WillOnce(Return(200))
    .WillOnce(Return(300));

However, I haven't found any docs for mocking multiple returns with ON_CALL.

Answer 1

ON_CALL is more used for setting default behavior of the function. I.e. you know that in tested code the mocked function is called, you want to set some default value, but it is not actually important how many times function is called.

The example:

  ON_CALL(foo, Sign(_))
      .WillByDefault(Return(-1));
  ON_CALL(foo, Sign(0))
      .WillByDefault(Return(0));
  ON_CALL(foo, Sign(Gt(0)))
      .WillByDefault(Return(1));

To get your desired behavior I'd use expectations - you already provided some example in question, just to show more - an example when you expect 1, 2 then always 3:

  EXPECT_CALL(foo, Sign(_))
      .WillOnce(Return(1))
      .WillOnce(Return(2))
      .WillRepeatedly(Return(3));

EXPECT_CALL "way" might be troublesome when you want to set this in test fixture SetUp - and some tests might call foo only once. But, of course, there are ways to "control" ON_CALL return value for subsequent calls - but you must do it with special actions - like getting result of some function - like in this example:

class IDummy
{
public:
    virtual int foo() = 0;
};

class DummyMock : public IDummy
{
public:
    MOCK_METHOD0(foo, int());
};
using namespace ::testing;
class DummyTestSuite : public Test
{
protected:
    DummyMock dummy;
    void SetUp() override
    {
        ON_CALL(dummy, foo())
           .WillByDefault(
                 InvokeWithoutArgs(this, &DummyTestSuite::IncrementDummy));
    }
    int dummyValue = 0;
    int IncrementDummy()
    {
        return ++dummyValue;
    }

};


TEST_F(DummyTestSuite, aaa)
{
    ASSERT_EQ(1, dummy.foo());
    ASSERT_EQ(2, dummy.foo());
    ASSERT_EQ(3, dummy.foo());

}