Unittests

Unit tests are a builtin framework of test cases applied to a module to determine if it is working properly. A D program can be run with unit tests enabled or disabled.

Unit tests are a special function defined like:

unittest
{
    // test code
}

Individual tests are specified in the unit test using assert expressions. There can be any number of unit test functions in a module, including within struct and class declarations. They are executed in lexical order. Unit tests, when enabled, are run after all static initialization is complete and before the main() function is called.

struct Sum
{
    int add(int x, int y) { return x + y; }

    unittest
    {
        Sum sum;
        assert(sum.add(3,4) == 7);
        assert(sum.add(-2,0) == -2);
    }
}

Practice

Navigate to the demo/binary-search directory. Inspect the source file binarySearch.d. As the name implies, a binarySearch algorithm is implemented on integers. Compile and run the file.

• Write a unittest function that tests some corner cases. Are there any bugs in the algorithm implementation? If so, fix them.
• Rewrite the binarySearch algorithm to make use of slices.