There's big difference between integration and unit tests. If you're having trouble writing unit tests, it's probably because your code is too tightly coupled, making it hard to separate one part from another.
When you try to write a project with tests, not necessarily test first, it will enforce certain design. This is almost always a good thing, since you're forced to write modular code.
When you try to write a project with tests, not necessarily test first, it will enforce certain design. This is almost always a good thing, since you're forced to write modular code.