Call list of methods in derived class

Question

I am developing a test-framework. There are a number of test-suites, each is a class with a set of member functions for each individual test.

I would like to find a way to dynamically iterate through all of the tests in a class.

The idealised setup might look something like this:

class A : public Test
{
public:
    A() {
        addTest(a);
        addTest(b);
        addTest(c);
    }

    void a() { cout << "A::a" << endl; }
    void b() { cout << "A::b" << endl; }
    void c() { cout << "A::c" << endl; }
};

The addTest() method will add its parameter to a list; this list is iterated through at a later point and each method is run.

Is there any way to achieve this? The closest we have come up with so far is this:

class Test
{
public:
    template <typename T>
    struct UnitTest
    {
        typedef void (T::*P)();
        P f;
        UnitTest(P p) : f(p) {}
    };
    // (this struct simplified: we also include a name and description)

    virtual void run(int testId) = 0;
};

class A : public Test
{
public:
    A() {
        mTests.push_back(UnitTest<A>(&A::a));
        mTests.push_back(UnitTest<A>(&A::b));
        mTests.push_back(UnitTest<A>(&A::c));
    }

    void a() { cout << "a" << endl; }
    void b() { cout << "b" << endl; }
    void c() { cout << "c" << endl; }

    // not ideal - this code has to be repeated in every test-suite
    void run(int testId)
    {
        (this->*(mTests[testId].f))();
    }
    vector<UnitTest<A>> mTests;
};

To invoke one test per-iteration of the main run-loop:

a->run(mTestId++);

This is not ideal because every test-suite (class) has to repeat the run() code and have its own mTests member.

Is there a way to get closer to the ideal?

Answer 1

Make each test a functor or function object. Create a container of pointers to the tests and then iterate over the container:

struct Test_Base_Class
{
  virtual bool Execute(void) = 0;
};

typedef std::vector<Test_Base_Class *> Container_Of_Tests;

struct Test_Engine
{
  Container_Of_Tests tests_to_run;

  void Add_Test(Test_Base_Class * p_new_test)
  {
    tests_to_run.push_back(p_new_test);
  }

  void Run_Tests(void)
  {
    Container_Of_Tests::iterator iter;
    for (iter = tests_to_run.begin();
         iter != tests_to_run.end();
         ++iter)
    {
       (*iter)->Execute(); // Invoke the Execute method on a test.
    }
    return;
  }
}

This is the foundation. I am currently using this pattern but have expanded to include a Resume() method and status reporting.