How to initialize test variables using Visual Studio CppUnitTestFramework - c++

Question

I'm writing a roboter controller class Controller in which I'm using a struct Axis for each of the 4 controllable motors.
For each test I want to reset everything, so I created a pointer in the class which is changed to a new Controller before each test method. The initialisation works fine in TEST_METHOD_INITIALIZE, but once any TEST_METHOD is called the program seems reset the Axis pointers.
Thanks for your help!
Edit: After further analysis I have the theory, that the initialised Axis objects Axis init_mx are deleted after the method is finished.
Edit2: I think this a slightly more complex problem like this: Pointer to local variable in C++
Nevertheless, I didn't find a way to reset the Axis variables at for every method without actually resetting each variable in it.
using namespace Microsoft::VisualStudio::CppUnitTestFramework;
...
namespace UnitTest
{
TEST_CLASS(UnitTestController)
{
public:
Controller* controller;
struct Axis *mx, *my, *mz, *mg;
TEST_METHOD_INITIALIZE(methodName)
{
Axis init_mx(50), init_my(50), init_mz(50), init_mg(5);
mx = &init_mx;
my = &init_my;
mz = &init_mz;
mg = &init_mg;
Controller init_controller(mx, my, mz, mg);
controller = &init_controller;
}
...
TEST_METHOD(id_3_next_mode)
{
mx->position = 5;
controller->getAxisPositionMx();
//Axis in pointers got reset and therefore have no pointers to the
//provided structs from TEST_METHOD_INITIALIZE
}
}
};
}
Controller.h(excerpt):
private:
struct Axis *mx, *my, *mz, *mg;
Controller.cpp (excerpt)
Controller::Controller(Axis *mx_in, Axis *my_in, Axis *mz_in, Axis *mg_in)
{
mx = mx_in;
my = my_in;
mz = mz_in;
mg = mg_in;
}

Answer 1

You found your original bug, but I think it's worth pointing out some details of how test modules, classes, methods, and the special initialize/cleanup methods are intended to work.
The most important thing to note is that a new instance of the class is instantiated every time a test method is executed, so each test will have a fresh set of class variables. This means that your example test class could look like:
TEST_CLASS(UnitTestController)
{
public:
struct Axis mx, my, mz, mg;
Controller controller;
// Define a constructor to initialize the class variables
UnitTestController() :
mx(50), my(50), mz(50), mg(50),
controller(mx, my, mz, mg)
{
}
TEST_METHOD(id_3_next_mode)
{
mx.position = 5;
controller.getAxisPositionMx();
}
};
If you wanted to have a variable persist between tests, you could put it outside the test class.
namespace UnitTest {
SomeClass moduleVar1;
TEST_CLASS(UnitTestClass)
{
public:
TEST_METHOD(TestMethod1)
{
Assert::IsTrue(moduleVar1.SomeMethod());
}
TEST_METHOD(TestMethod2)
{
Assert::IsFalse(moduleVar1.SomeOtherMethod());
}
};
}
The framework also provides the following Initialize and Cleanup functions which can be used to manipulate the test environment and fixtures:
TEST_METHOD_INITIALIZE - Called once before running each test method.
TEST_METHOD_CLEANUP - Called once after running each test method.
TEST_CLASS_INITIALIZE - Called once per module before running any tests belonging to this class.
TEST_CLASS_CLEANUP - Called once per module after running all tests belonging to this class.
TEST_MODULE_INITIALIZE - Called once per module before running any tests or class initalizers.
TEST_MODULE_CLEANUP - Called once per module after running all tests and class cleanups.