0dc0bea945
* Add xcAwaitDeferred to aid with tests that have publishers. * Improve naming * Address Comments - Fix naming - Add optional expectation message - Use trailing closure syntax
64 lines
2.5 KiB
Swift
64 lines
2.5 KiB
Swift
//
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// Copyright 2023 New Vector Ltd
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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import Combine
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import XCTest
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extension XCTestCase {
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/// XCTest utility that assists in subscribing to a publisher and deferring the fulfilment and results until some other actions have been performed.
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///
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/// ```
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/// let collectedEvents = somePublisher.collect(3).first()
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/// let awaitDeferred = deferFulfillment(collectedEvents)
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/// // Do some other work that publishes to somePublisher
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/// XCTAssertEqual(try await awaitDeferred.execute(), [expected, values, here])
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/// ```
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/// - Parameters:
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/// - publisher: The publisher to wait on.
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/// - timeout: A timeout after which we give up.
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/// - Returns: The deferred fulfilment to be executed after some actions and that returns the result of the publisher.
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func deferFulfillment<T: Publisher>(_ publisher: T, timeout: TimeInterval = 10, message: String? = nil) -> DeferredFulfillment<T.Output> {
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var result: Result<T.Output, Error>?
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let expectation = expectation(description: message ?? "Awaiting publisher")
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let cancellable = publisher
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.sink { completion in
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switch completion {
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case .failure(let error):
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result = .failure(error)
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case .finished:
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break
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}
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expectation.fulfill()
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} receiveValue: { value in
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result = .success(value)
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}
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return DeferredFulfillment<T.Output> {
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await self.fulfillment(of: [expectation], timeout: timeout)
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cancellable.cancel()
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let unwrappedResult = try XCTUnwrap(result, "Awaited publisher did not produce any output")
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return try unwrappedResult.get()
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}
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}
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struct DeferredFulfillment<T> {
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let closure: () async throws -> T
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@discardableResult func fulfill() async throws -> T {
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try await closure()
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}
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}
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}
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