swift-testing-wait-until

name	swift-testing-wait-until
description	Use when a test needs to wait for an async state change instead of a fixed delay — the `no_task_sleep_in_tests` lint rule bans arbitrary `Task.sleep` in tests because it causes flaky failures. Provides the `waitUntil` polling helper to add to a test target instead.

waitUntil: No Task.sleep in Tests

Wait for the actual state change instead of a fixed delay. Add this TestHelpers.swift to your test target (the lint rules already exclude *TestHelpers.swift):

import Foundation

/// Thrown by `waitUntil` when the condition never became true within the timeout.
struct WaitTimeoutError: Error, CustomStringConvertible {
    let timeout: Duration
    var description: String { "waitUntil timed out after \(timeout)" }
}

/// Polls `condition` until true, throwing on timeout. Runs on the caller's actor
/// (via `#isolation`) so the closure may read `@MainActor` fixtures safely.
func waitUntil(
    timeout: Duration = .seconds(2),
    pollInterval: Duration = .milliseconds(10),
    isolation _: isolated (any Actor)? = #isolation,
    _ condition: () -> Bool
) async throws {
    let clock = ContinuousClock()
    let deadline = clock.now.advanced(by: timeout)
    while !condition() {
        guard clock.now < deadline else { throw WaitTimeoutError(timeout: timeout) }
        try await Task.sleep(for: pollInterval)
    }
}

Usage: try await waitUntil { viewModel.isLoaded } instead of try await Task.sleep(for: .seconds(1)).