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 obtained one other sport changer: Swift Testing. It’s so a lot enjoyable to make use of, you’ll be leaping off the 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 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 can assist to make it even higher.
Swift Testing vs. XCTest
Right here’s a fast checklist of variations:
- You mark a operate with
@Check
as a substitute of beginning its title withcheck
. - Check capabilities will be occasion strategies, static strategies, or world capabilities.
- 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.
- Exams run in parallel utilizing Swift concurrency, together with on gadgets.
- You employ
#anticipate(...)
orattempt #require(...)
as a substitute ofXCTAssertTrue
,...False
,...Nil
,...NotNil
,...Equal
,...NotEqual
,...Similar
,...NotIdentical
,...GreaterThan
,...LessThanOrEqual
,...GreaterThanOrEqual
or...LessThan
.
Hold studying to see extra particulars.
Getting Began
Observe: 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 consumer’s guess is greater or decrease than the goal.
First, remark out the final check 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 traditional 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 check, you possibly can embrace a de-initializer. However this requires the sort to be an actor or class — it’s the most typical cause to make use of a reference kind as a substitute 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 check operate 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 traditional 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 simple 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 crimson X:
And click on the Present button:
It reveals 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 should create a brand new goal to write down Swift Testing assessments, so you possibly can 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 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 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 Choice-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. Exchange testExample()
with a check to test that this occurs:
@Check func rhinoQuery() async throws {
attempt await sut.fetchObjects(for: "rhino")
#anticipate(sut.objects.rely == 3)
}
Run this check … success!
Write one other check:
@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 need to check different question phrases. You can hold doing copy-paste-edit, however top-of-the-line 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 check:
The label and every of the arguments seem within the Check navigator. The 4 assessments ran in parallel, utilizing Swift concurrency. Every check 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 search out the issue.