func testTimerIsStarted() {
    let expectation = self.expectation(description: #function)

    let timer = DispatchSource.createRepeating(interval: 0, deadline: DispatchTime.now()) {
        expectation.fulfill()
    }
    waitForExpectations(timeout: 0.02)
}

func testTimerIsStarted() {
    let expectation = self.expectation(description: #function)

    let timer = DispatchSource.createRepeating(interval: 0, deadline: DispatchTime.now()) {
        expectation.fulfill()
    }

    withExtendedLifetime(timer) { timer in
        waitForExpectations(timeout: 0.02)
    }
}