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

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")
}