Making async tests faster and more stable
Discover page available: Unit TestingHere are some quick tips to make async tests faster & more stable:
- Avoid
sleep()
- use expectations instead. - Use generous timeouts to avoid flakiness on CI.
- Put all assertions at the end of each test, not inside closures.
// BEFORE:
class MentionDetectorTests: XCTestCase {
func testDetectingMention() {
let detector = MentionDetector()
let string = "This test was written by @johnsundell."
detector.detectMentions(in: string) { mentions in
XCTAssertEqual(mentions, ["johnsundell"])
}
sleep(2)
}
}
// AFTER:
class MentionDetectorTests: XCTestCase {
func testDetectingMention() {
let detector = MentionDetector()
let string = "This test was written by @johnsundell."
var mentions: [String]?
let expectation = self.expectation(description: #function)
detector.detectMentions(in: string) {
mentions = $0
expectation.fulfill()
}
waitForExpectations(timeout: 10)
XCTAssertEqual(mentions, ["johnsundell"])
}
}
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