How to do one-time setup for your tests

Swift version: 5.2

Paul Hudson @twostraws May 28th 2019

When you create a default XCTestCase using Xcode you’ll get default setUp() and tearDown() methods like these:

override func setUp() {
    super.setUp()
    // Put setup code here. This method is called before the invocation of each test method in the class.
}

override func tearDown() {
    // Put teardown code here. This method is called after the invocation of each test method in the class.
    super.tearDown()
}

Those are called before and after every test inside your XCTestCase subclass, which allows you to reset your testing environment fully. However, sometimes you prefer to do some setup once and keep that state during all your tests, for example if you need to generate some test data that gets shared in all your tests.

As well as the regular setUp() and tearDown() instance methods, you can also define class methods with the same names, like this:

override class func setUp() {
    super.setUp()
}

override class func tearDown() {
    super.tearDown()
}

Unlike their instance method equivalents, these two class methods will be run only once each: setUp() before all your tests are run, and tearDown() after all your tests have completed.