iOS Unit Testing by Example

Drill into a Partially Covered Line

Let’s start writing a test for the max function, keeping an eye on the code coverage as we progress. Delete test_zero, then add the beginnings of the new test:

CodeCoverage/CodeCoverageTests/CoveredClassTests.swift

func test_max_with1And2_shouldReturnSomething() {
    let result = CoveredClass.max(1, 2)
}

Note that there’s no assertion yet. Run tests and go to CoveredClass.swift to see the line-by-line coverage. It should look something like this:

The code coverage gutter now shows a smaller red area and two numbers. The 0 marks the section that tests haven’t touched. Above that is a 1, marking ...