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 jot down extra unit exams for all of your apps! No extra gritting your tooth over XCTAssert-this-and-that. You get to jot down in Swift, utilizing Swift concurrency, no much less. Swift Testing is a factor of magnificence, and Apple’s testing workforce is rightfully pleased with its achievement. You’ll have the ability to write exams quicker and with larger management, your exams will run on Linux and Home windows, and Swift Testing is open supply, so you can assist to make it even higher.

Swift Testing vs. XCTest

Right here’s a fast record of variations:

• You mark a operate with @Check as an alternative of beginning its title with take a look at.
• Check features might be occasion strategies, static strategies, or international features.
• 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.
• Exams run in parallel utilizing Swift concurrency, together with on units.
• You utilize #count on(...) or strive #require(...) as an alternative of XCTAssertTrue, ...False, ...Nil, ...NotNil, ...Equal, ...NotEqual, ...An identical, ...NotIdentical, ...GreaterThan, ...LessThanOrEqual, ...GreaterThanOrEqual or ...LessThan.

Maintain 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 prime or backside of this text to obtain the starter initiatives. There are two initiatives so that you can work with:

Migrating to Swift Testing

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

These exams verify that BullsEyeGame computes the rating accurately when the person’s guess is increased 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 exchange import XCTest with:

import Testing

Then, exchange 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. If you happen to should carry out logic after every take a look at, you possibly can embody 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, exchange 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, exchange func testScoreIsComputedWhenGuessIsHigherThanTarget() { with:

@Check func scoreIsComputedWhenGuessIsHigherThanTarget() {

and exchange the XCTAssertEqual line with:

#count on(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
  #count on(sut.scoreRound == 95)
}

Then, run BullsEyeTests within the ordinary 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 exams full with success:

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

#count on(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 exhibits 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 need to create a brand new goal to jot down Swift Testing exams, so you possibly can migrate your exams incrementally. However don’t name XCTest assertion features from Swift Testing exams or use the #count on 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, take 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 may 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 `#count on(...)` 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. Exchange testExample() with a take a look at to verify that this occurs:

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

Run this take a look at … success!

Write one other take a look at:

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

Parameterized Testing

Once more, it succeeds! These two exams are very related. Suppose you wish to take a look at different question phrases. You may preserve doing copy-paste-edit, however top-of-the-line options of Swift Testing is parameterized exams. Remark out or exchange your two exams with this:

@Check("Variety of objects fetched", arguments: [
        "rhino",
        "cat",
        "peony",
        "ocean",
    ])
func objectsCount(question: String) async throws {
  strive await sut.fetchObjects(for: question)
  #count on(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 exams ran in parallel, utilizing Swift concurrency. Every take a look at used its personal copy of sut. If one of many exams had failed, it would not cease any of the others, and also you’d have the ability to see which of them failed, then rerun solely these to search out the issue.