Unit tests: testing for exceptions

import std.stdio;
import std.exception; // assertThrown(), assertNotThrown()

class MyException : Exception
{
    this(string msg = "")
    {
        super(msg);
    }
}

int add(const int a, const int b)
{
    if (a < 0 || b < 0)
    {
        throw new MyException("cannot be called with negative values");
    }
    //
    return a + b;
}

int product(const int a, const int b)
{
    return a * b;
}

void main()
{
    writeln(add(2, 3));
}

// ---

unittest
{
    assert(add(2, 3) == 5);
    assertThrown(add(-2, 3) == 1); // must throw an exception (of any type)
    assertThrown!MyException(add(-2, 3) == 1); // must throw this type of exception

    assert(product(2, 5) == 10);
    assert(product(2, 3) == 6);
    assertNotThrown(product(2, 3) == 19); // it only checks that product(2, 3) doesn't throw an exception
}