iOS Unit Testing by Example

Start from Test Zero

Now we have a home for our next set of tests. Before we get into our experiments around life cycles, I’d like to show you a trick. First, whenever I create a new test suite, I start with a special test I call Test Zero. Add the following test to MyClassTests:

LifeCycle/LifeCycleTests/MyClassTests.swift

func test_zero() {
    XCTFail("Tests not yet implemented in MyClassTests")
}

I call it Test Zero because it precedes the first real test we want to write. Go ahead and run tests to make sure it fails. Why? This is a check of our infrastructure. It confirms that our basic test plumbing is correct.

Test Zero helps separate our problems so we can tackle them one at a time. When we create a new test suite, we’re usually ...