CODEWITHSUNDEEP
c++testingmockingtdd
Radek
Radek

Reputation: 329

Mock object c++

I was reading about TDD and wondering is it possible to write any mock object without using extra test library like easyMock or sth like that.

For example I have code:

class Person
{
  int age;
  int add ( int x) { return this.age + x }
}

How to write mock object to test above code ?

Upvotes: 1

Views: 1162

Answers (2)

eerorika
eerorika

Reputation: 238491

You don't test a classes like that with a mock of that class. You test interfaces. In fact, your code looks like it could be a mock object to test some other code.

// defined in code that is being tested
class Person {
    virtual int add(int) = 0;
}
void foo(const Person& bar) {
    // use person somehow
}

To test the above interface, you can create a mock object. This object does not have the requirements that a real implementation might have. For example while a real implementation might require a database connection, the mock object does not.

class Mock: public Person {
    int add(int x) {
        // do something less complex than real implementation would
        return x;
    }
}

Mock test;
foo(test);

Using inheritance is not necessary if you want to test say, a template function.

template<class T>
void foo(T bar) {
    // Code that uses T.add()
}

To test interface like this, you can define mock object like this

class Mock {
    int add(int x) {
        // do something less complex than real implementation would
        return x;
    }
}

Upvotes: 2

Zac Howland
Zac Howland

Reputation: 15870

Mocking is useful when you have external resources used in your code (e.g. databases, files, etc). To do this, you would implement those interfaces in such a way that it would "fake" the required steps so that the code you are actually testing (your business logic) can be tested without having to worry about a false-negative test due to situations in the external resources.

The code you have posted does not require mocking to test it.

Upvotes: 0

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