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 put in writing extra unit assessments for all of your apps! No extra gritting your tooth over XCTAssert-this-and-that. You get to put in writing in Swift, utilizing Swift concurrency, no much less. Swift Testing is a factor of magnificence, and Apple’s testing group is rightfully happy with its achievement. You’ll be capable to write assessments quicker and with better management, your assessments will run on Linux and Home windows, and Swift Testing is open supply, so you may help to make it even higher.

Swift Testing vs. XCTest

Right here’s a fast record of variations:

• You mark a perform with @Check as an alternative of beginning its identify with take a look at.
• Check capabilities could be occasion strategies, static strategies, or international capabilities.
• Swift Testing has a number of traits you need to use 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.
• Checks run in parallel utilizing Swift concurrency, together with on units.
• You employ #anticipate(...) or attempt #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 assessments test 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) help 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 need to use a struct, actor, or class. As common in Swift, struct is inspired as a result of it makes use of worth semantics and avoids bugs from unintentional state sharing. For those who 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 commonest motive to make use of a reference kind as an alternative of a struct.

Subsequent, change setUpWithError() with an init methodology:

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 perform to:

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

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

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

Then, run BullsEyeTests within the common 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 perform, change == to !=:

#anticipate(sut.scoreRound != 95)

To see the failure message, run this take a look at after which click on the purple 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, they usually’re all XCTests. You didn’t need to create a brand new goal to put in writing 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, take a look at your new goal’s Normal/Deployment Information:

Not surprisingly, it’s iOS 18.0. However TheMet’s deployment is iOS 17.4. You’ll be able to 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 test 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:) methodology that downloads at most maxIndex objects. The app begins with the question “rhino”, which fetches three objects. Substitute testExample() with a take a look at to test 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 comparable. Suppose you wish to take a look at different question phrases. You would maintain 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 to see which of them failed, then rerun solely these to seek out the issue.