Googlemock can help build mock classes with which it is possible to detect if one method calls another method and with what parameters, and influence the behaviour of the called method.
E.g., to test that method a() in class UnderTest actually calls method b()
class UnderTest {
public:
/// Method a() calls method b().
virtual void a() {b();}
/// Method b() does nothing.
virtual void b() {}
};
one can write a mock class which overwrites method b()
class UnderTestMock : public UnderTest {
public:
MOCK_METHOD0(b, void());
};
and test if the method b() is actually called after calling method a():
TEST(UnderTest, aCallsB) {
UnderTestMock mock;
EXPECT_CALL(mock, b());
mock.a();
}
Can I use Googlemock like this with C++Builder 11.2?
No, at the moment it is not possible to use Googlemock like this with C++Builder 11.2.
The Googletest project (which includes Googlemock) itself has removed all support for C++Builder in 2019. Embarcadero has since published their own patched version of Googletest in a GetIt package, which includes project files to build Googletest and Googlemock and some usage examples.
The Googlemock-related project files are all somewhat broken, e.g. the gmock.cbproj file inserts a source file into the gmock.a library that performs some unrelated tests on Googletest. These project file errors can all be fixed easily by removing source files from the projects that do not belong there and rebuild.
However, after fixing the gmock.cbproj project file, it turns out that the main feature of Googlemock, the EXPECT_CALL() macro, is not supported by C++Builder 11.2:
This is a simple source file which puts the code pieces from the question together, adds a main function and the required includes:
#include "gmock/gmock.h"
#include "gtest/gtest.h"
#include <tchar.h>
int _tmain(int argc, _TCHAR* argv[])
{
testing::InitGoogleTest(&argc, argv);
return RUN_ALL_TESTS();
}
class UnderTest {
public:
/// Method a() calls method b().
virtual void a() {b();}
/// Method b() does nothing.
virtual void b() {}
};
class UnderTestMock : public UnderTest {
public:
MOCK_METHOD0(b, void());
};
TEST(UnderTest, aCallsB) {
UnderTestMock mock;
EXPECT_CALL(mock, b());
mock.a();
}
This sample works fine with Googlemock with other compilers (at most, tchar, _tmain need to be replaced with char, main), however, with C++Builder, some required features are missing from either the compiler or from the C++ standard library. The error message when compiling with C++Builder's clang-based 64-bit compiler is
Build FAILED.
C:\Users\...\Documents\Embarcadero\Studio\22.0\CatalogRepository\GoogleTest-2021.09\googlemock\include\gmock/gmock-nice-strict.h(134,6): C++ warning : __declspec attribute 'empty_bases' is not supported
C:\Users\...\Documents\Embarcadero\Studio\22.0\CatalogRepository\GoogleTest-2021.09\googlemock\include\gmock/gmock-nice-strict.h(174,6): C++ warning : __declspec attribute 'empty_bases' is not supported
C:\Users\...\Documents\Embarcadero\Studio\22.0\CatalogRepository\GoogleTest-2021.09\googlemock\include\gmock/gmock-nice-strict.h(215,6): C++ warning : __declspec attribute 'empty_bases' is not supported
c:\program files (x86)\embarcadero\studio\22.0\include\dinkumware64\type_traits(2686,1): C++ error : no matching function for call to 'invoke'
c:\program files (x86)\embarcadero\studio\22.0\include\dinkumware64\functional(216,10): C++ error : > in instantiation of function template specialization 'std::_Invoke_ret<void, testing::internal::DoDefaultAction &>' requested here
c:\program files (x86)\embarcadero\studio\22.0\include\dinkumware64\functional(165,2): C++ error : > in instantiation of member function 'std::_Func_impl<testing::internal::DoDefaultAction, std::allocator<int>, void>::_Do_call' requested here
c:\program files (x86)\embarcadero\studio\22.0\include\dinkumware64\xmemory0(704,23): C++ error : > in instantiation of function template specialization 'std::_Func_impl<testing::internal::DoDefaultAction, std::allocator<int>, void>::_Func_impl<testing::internal::DoDefaultAction, const std::allocator<int> &>' requested here
c:\program files (x86)\embarcadero\studio\22.0\include\dinkumware64\xmemory0(845,6): C++ error : > in instantiation of function template specialization 'std::allocator<std::_Func_impl<testing::internal::DoDefaultAction, std::allocator<int>, void> >::construct<std::_Func_impl<testing::internal::DoDefaultAction, std::allocator<int>, void>, testing::internal::DoDefaultAction, const std::allocator<int> &>' requested here
c:\program files (x86)\embarcadero\studio\22.0\include\dinkumware64\xmemory0(994,13): C++ error : > in instantiation of function template specialization 'std::allocator_traits<std::allocator<std::_Func_impl<testing::internal::DoDefaultAction, std::allocator<int>, void> > >::construct<std::_Func_impl<testing::internal::DoDefaultAction, std::allocator<int>, void>, testing::internal::DoDefaultAction, const std::allocator<int> &>' requested here
c:\program files (x86)\embarcadero\studio\22.0\include\dinkumware64\functional(376,6): C++ error : > (skipping 6 contexts in backtrace; use -ftemplate-backtrace-limit=0 to see all)
C:\Users\...\Documents\Embarcadero\Studio\22.0\CatalogRepository\GoogleTest-2021.09\googlemock\include\gmock/gmock-actions.h(470,4): C++ error : > in instantiation of function template specialization 'testing::Action<void ()>::Init<testing::internal::DoDefaultAction>' requested here
C:\Users\...\Documents\Embarcadero\Studio\22.0\CatalogRepository\GoogleTest-2021.09\googlemock\include\gmock/gmock-spec-builders.h(909,8): C++ error : > in instantiation of function template specialization 'testing::Action<void ()>::Action<testing::internal::DoDefaultAction, void>' requested here
C:\Users\...\Documents\Embarcadero\Studio\22.0\CatalogRepository\GoogleTest-2021.09\googlemock\include\gmock/gmock-spec-builders.h(1629,12): C++ error : > in instantiation of member function 'testing::internal::TypedExpectation<void ()>::TypedExpectation' requested here
C:\Users\...\Documents\Embarcadero\Studio\22.0\CatalogRepository\GoogleTest-2021.09\googlemock\include\gmock/gmock-spec-builders.h(1284,29): C++ error : > in instantiation of member function 'testing::internal::FunctionMocker<void ()>::AddNewExpectation' requested here
C:\Users\...\Documents\Embarcadero\Studio\Projects\gmocktest\main.cpp(26,2): C++ error : > in instantiation of member function 'testing::internal::MockSpec<void ()>::InternalExpectedAt' requested here
c:\program files (x86)\embarcadero\studio\22.0\include\dinkumware64\type_traits(2664,6): C++ error : > candidate template ignored: substitution failure [with _Callable = testing::internal::DoDefaultAction &, _Types = <>]: no matching function for call to '_Call'
3 Warning(s)
13 Error(s)
The two example projects included in the GetIt package for Googlemock hint that some isolated aspects of Googlemock may be working, like at least one Googlemock matcher works inside the EXPECT_THAT() macro, but none of the examples compiled by the GetIt package make use of the main feature of Googlemock, the EXPECT_CALL() macro.