Swift Testing: Getting Began | Kodeco

In 2021, Apple launched Swift concurrency to an adoring viewers; lastly, builders may write Swift code to implement concurrency in Swift apps! At WWDC 2024, builders received one other sport changer: Swift Testing. It’s so a lot enjoyable to make use of, you’ll be leaping away from bed each morning, keen to write down extra unit checks for all of your apps! No extra gritting your enamel over XCTAssert-this-and-that. You get to write down in Swift, utilizing Swift concurrency, no much less. Swift Testing is a factor of magnificence, and Apple’s testing group is rightfully pleased with its achievement. You’ll be capable of write checks quicker and with better management, your checks will run on Linux and Home windows, and Swift Testing is open supply, so you will help to make it even higher.

Swift Testing vs. XCTest

Right here’s a fast listing of variations:

• You mark a operate with @Check as an alternative of beginning its title with check.
• Check features may be occasion strategies, static strategies, or world features.
• Swift Testing has a number of traits you need to use so as to add descriptive details about a check, customise when or whether or not a check runs, or modify how a check behaves.
• Checks run in parallel utilizing Swift concurrency, together with on units.
• You employ #anticipate(...) or strive #require(...) as an alternative of XCTAssertTrue, ...False, ...Nil, ...NotNil, ...Equal, ...NotEqual, ...An identical, ...NotIdentical, ...GreaterThan, ...LessThanOrEqual, ...GreaterThanOrEqual or ...LessThan.

Preserve studying to see extra particulars.

Getting Began

Word: You want Xcode 16 beta to make use of Swift Testing.

Click on the Obtain Supplies button on the high or backside of this text to obtain the starter tasks. There are two tasks so that you can work with:

Migrating to Swift Testing

To begin, open the BullsEye app in Xcode 16 beta and find BullsEyeTests within the Check navigator.

These checks verify that BullsEyeGame computes the rating appropriately when the person’s guess is larger or decrease than the goal.

First, remark out the final check testScoreIsComputedPerformance(). Swift Testing doesn’t (but) assist UI efficiency testing APIs like XCTMetric or automation APIs like XCUIApplication.

Return to the highest and substitute import XCTest with:

import Testing

Then, substitute class BullsEyeTests: XCTestCase { with:

struct BullsEyeTests {

In Swift Testing, you need to use a struct, actor, or class. As traditional in Swift, struct is inspired as a result of it makes use of worth semantics and avoids bugs from unintentional state sharing. In case you should carry out logic after every check, you’ll be able to embrace a de-initializer. However this requires the kind to be an actor or class — it’s the commonest purpose to make use of a reference kind as an alternative of a struct.

Subsequent, substitute setUpWithError() with an init technique:

init() {
  sut = BullsEyeGame()
}

This allows you to take away the implicit unwrapping from the sut declaration above:

var sut: BullsEyeGame

Remark out tearDownWithError().

Subsequent, substitute func testScoreIsComputedWhenGuessIsHigherThanTarget() { with:

@Check func scoreIsComputedWhenGuessIsHigherThanTarget() {

and substitute the XCTAssertEqual line with:

#anticipate(sut.scoreRound == 95)

Equally, replace the second check operate to:

@Check func scoreIsComputedWhenGuessIsLowerThanTarget() {
  // 1. given
  let guess = sut.targetValue - 5

  // 2. when
  sut.verify(guess: guess)

  // 3. then
  #anticipate(sut.scoreRound == 95)
}

Then, run BullsEyeTests within the traditional manner: Click on the diamond subsequent to BullsEyeTests within the Check navigator or subsequent to struct BullsEyeTests within the editor. The app builds and runs within the simulator, after which the checks full with success:

Now, see how straightforward it’s to alter the anticipated situation: In both check operate, change == to !=:

#anticipate(sut.scoreRound != 95)

To see the failure message, run this check after which click on the pink X:

And click on the Present button:

It exhibits you the worth of sut.scoreRound.

Undo the change again to ==.

Discover the opposite check teams are nonetheless there, and so they’re all XCTests. You didn’t need to create a brand new goal to write down Swift Testing checks, so you’ll be able to migrate your checks incrementally. However don’t name XCTest assertion features from Swift Testing checks or use the #anticipate macro in XCTests.

Including Swift Testing

Shut BullsEye and open TheMet. This app has no testing goal, so add one:

Testing System defaults to Swift Testing:

Now, have a look at your new goal’s Common/Deployment Information:

Not surprisingly, it’s iOS 18.0. However TheMet’s deployment is iOS 17.4. You possibly can change one or the opposite, however they should match. I’ve modified TheMet’s deployment to iOS 18.

Open TheMetTests within the Check navigator to see what you bought:

import Testing

struct TheMetTests {

    @Check func testExample() async throws {
        // Write your check right here and use APIs like `#anticipate(...)` to verify anticipated situations.
    }

}

You’ll want the app’s module, so import that:

@testable import TheMet

You’ll be testing TheMetStore, the place all of the logic is, so declare it and initialize it:

var sut: TheMetStore

init() async throws {
  sut = TheMetStore()
}

Press Shift-Command-O, kind the, then Choice-click TheMetStore.swift to open it in an assistant editor. It has a fetchObjects(for:) technique that downloads at most maxIndex objects. The app begins with the question “rhino”, which fetches three objects. Change testExample() with a check to verify that this occurs:

@Check func rhinoQuery() async throws {
  strive await sut.fetchObjects(for: "rhino")
  #anticipate(sut.objects.depend == 3)
}

Run this check … success!

Write one other check:

@Check func catQuery() async throws {
  strive await sut.fetchObjects(for: "cat")
  #anticipate(sut.objects.depend <= sut.maxIndex)
}

Parameterized Testing

Once more, it succeeds! These two checks are very comparable. Suppose you need to check different question phrases. You may hold doing copy-paste-edit, however among the best options of Swift Testing is parameterized checks. Remark out or substitute your two checks with this:

@Check("Variety of objects fetched", arguments: [
        "rhino",
        "cat",
        "peony",
        "ocean",
    ])
func objectsCount(question: String) async throws {
  strive await sut.fetchObjects(for: question)
  #anticipate(sut.objects.depend <= sut.maxIndex)
}

And run the check:

The label and every of the arguments seem within the Check navigator. The 4 checks ran in parallel, utilizing Swift concurrency. Every check used its personal copy of sut. If one of many checks had failed, it would not cease any of the others, and also you’d be capable of see which of them failed, then rerun solely these to search out the issue.