How to wait in a XCTest for T seconds without timeout error?

Question

I want to delay progression of a test for T seconds, without generating a timeout.

First I tried the obvious:

sleep(5)
XCTAssert(<test if state is correct after this delay>)

But that failed.

Then I tried:

let promise = expectation(description: "Just wait 5 seconds")
waitForExpectations(timeout: 5) { (error) in
    promise.fulfill()

    XCTAssert(<test if state is correct after this delay>)
}

My XCTAssert() now succeeded. But waitForExpectations() failed with a timeout.

This is according to the documentation of XCTest wait functions saying:

Timeout is always treated as a test failure.

What are my options?

ZGski · Accepted Answer · 2022-09-20 15:28:22Z

84

You can use XCTWaiter.wait functions.

For example:

let exp = expectation(description: "Test after 5 seconds")
let result = XCTWaiter.wait(for: [exp], timeout: 5.0)
if result == XCTWaiter.Result.timedOut {
    XCTAssert(<test if state is correct after this delay>)
} else {
    XCTFail("Delay interrupted")
}

edited Sep 20, 2022 at 15:28

ZGski

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answered May 9, 2018 at 7:45

A.Munzer

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1 Comment

Satyam Over a year ago

(1) Where should I call my method to test (2) How to set the expectation as fulfil?

Robin Stewart · Accepted Answer · 2021-01-10 19:58:10Z

32

If you know how much time something will take and simply want to wait that duration before continuing the test, you can use this one line:

_ = XCTWaiter.wait(for: [expectation(description: "Wait for n seconds")], timeout: 2.0)

answered Jan 10, 2021 at 19:58

Robin Stewart

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Comments

Bartłomiej Semańczyk · Accepted Answer · 2023-03-08 08:02:54Z

13

What best worked for me was:

let timeInSeconds = 2.0 // time you need for other tasks to be finished
let expectation = XCTestExpectation(description: "Your expectation")

DispatchQueue.main.asyncAfter(deadline: .now() + timeInSeconds) {
    expectation.fulfill()
}    

wait(for: [expectation], timeout: timeInSeconds + 1.0) // make sure it's more than what you used in AsyncAfter call.

//do your XCTAssertions here
XCTAssertNotNil(value)

edited Mar 8, 2023 at 8:02

Bartłomiej Semańczyk

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answered Mar 26, 2021 at 13:25

André Henrique da Silva

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Comments

lucianoenrico · Accepted Answer · 2025-05-08 06:57:41Z

0

if you need or prefer to work with async/await you can use something like the following:

    func wait(seconds: TimeInterval) async {
        let expectation = XCTestExpectation(description: "Wait utility")
        DispatchQueue.main.asyncAfter(deadline: .now() + seconds) {
            expectation.fulfill()
        }
        await fulfillment(of: [expectation], timeout: seconds + 1)
    }

answered May 8, 2025 at 6:57

lucianoenrico

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