Swift Testing: Getting Began | Kodeco

In 2021, Apple launched Swift concurrency to an adoring viewers; lastly, builders might write Swift code to implement concurrency in Swift apps! At WWDC 2024, builders acquired 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 assessments for all of your apps! No extra gritting your tooth 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 assessments quicker and with better management, your assessments 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 a substitute of beginning its identify with take a look at.
• Check capabilities may be occasion strategies, static strategies, or international capabilities.
• Swift Testing has a number of traits you should utilize so as to add descriptive details about a take a look at, customise when or whether or not a take a look at runs, or modify how a take a look at behaves.
• Assessments run in parallel utilizing Swift concurrency, together with on gadgets.
• You employ #anticipate(...) or attempt #require(...) as a substitute of XCTAssertTrue, ...False, ...Nil, ...NotNil, ...Equal, ...NotEqual, ...An identical, ...NotIdentical, ...GreaterThan, ...LessThanOrEqual, ...GreaterThanOrEqual or ...LessThan.

Maintain studying to see extra particulars.

Getting Began

Be aware: 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 assessments verify that BullsEyeGame computes the rating appropriately when the person’s guess is larger or decrease than the goal.

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

Return to the highest and change import XCTest with:

import Testing

Then, change class BullsEyeTests: XCTestCase { with:

struct BullsEyeTests {

In Swift Testing, you should utilize a struct, actor, or class. As ordinary in Swift, struct is inspired as a result of it makes use of worth semantics and avoids bugs from unintentional state sharing. In the event you should carry out logic after every take a look at, you’ll be able to embrace a de-initializer. However this requires the sort to be an actor or class — it’s the most typical purpose to make use of a reference kind as a substitute of a struct.

Subsequent, change 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, change func testScoreIsComputedWhenGuessIsHigherThanTarget() { with:

@Check func scoreIsComputedWhenGuessIsHigherThanTarget() {

and change the XCTAssertEqual line with:

#anticipate(sut.scoreRound == 95)

Equally, replace the second take a look at 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 ordinary means: 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 assessments full with success:

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

#anticipate(sut.scoreRound != 95)

To see the failure message, run this take a look at after which click on the pink X:

And click on the Present button:

It reveals you the worth of sut.scoreRound.

Undo the change again to ==.

Discover the opposite take a look at teams are nonetheless there, and so they’re all XCTests. You didn’t must create a brand new goal to write down Swift Testing assessments, so you’ll be able to migrate your assessments incrementally. However don’t name XCTest assertion capabilities from Swift Testing assessments 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 Data:

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 take a look at 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 Possibility-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. Exchange testExample() with a take a look at to verify that this occurs:

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

Run this take a look at … success!

Write one other take a look at:

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

Parameterized Testing

Once more, it succeeds! These two assessments are very related. Suppose you wish to take a look at different question phrases. You might hold doing copy-paste-edit, however among the best options of Swift Testing is parameterized assessments. Remark out or change your two assessments with this:

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

And run the take a look at:

The label and every of the arguments seem within the Check navigator. The 4 assessments ran in parallel, utilizing Swift concurrency. Every take a look at used its personal copy of sut. If one of many assessments 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.