Combine Expectations

用于测试的实用工具，可以等待 Combine 发布者。

最新版本: 版本 0.10.0 (2021 年 8 月 11 日) • 发行说明

要求: iOS 13+、macOS 10.15+ 和 tvOS 13+ 需要 Swift 5.1+ 或 Xcode 11+。watchOS 7.4+ 需要 Swift 5.4+ 或 Xcode 12.5+。

联系方式: 在 Github issues 中报告错误和提问。

使用 XCTestExpectation 测试 Combine 发布者通常需要设置大量样板代码。

CombineExpectations 旨在简化这些测试。它定义了一个 XCTestCase 方法，用于等待发布者期望。

用法

等待 发布者期望 可以使您的测试如下所示

import XCTest
import CombineExpectations

class PublisherTests: XCTestCase {
    func testElements() throws {
        // 1. Create a publisher
        let publisher = ...
        
        // 2. Start recording the publisher
        let recorder = publisher.record()
        
        // 3. Wait for a publisher expectation
        let elements = try wait(for: recorder.elements, timeout: ..., description: "Elements")
        
        // 4. Test the result of the expectation
        XCTAssertEqual(elements, ["Hello", "World!"])
    }
}

当您等待发布者期望时

您可以多次等待发布者

class PublisherTests: XCTestCase {
    func testPublisher() throws {
        let publisher = ...
        let recorder = publisher.record()
        
        // Wait for first element
        _ = try wait(for: recorder.next(), timeout: ...)
        
        // Wait for second element
        _ = try wait(for: recorder.next(), timeout: ...)
        
        // Wait for successful completion
        try wait(for: recorder.finished, timeout: ...)
    }
}

并非所有测试都必须等待，因为某些发布者期望会立即满足。 在这种情况下，首选同步 get() 方法，而不是 wait(for:timeout:)，如下所示

class PublisherTests: XCTestCase {
    func testSynchronousPublisher() throws {
        // 1. Create a publisher
        let publisher = ...
        
        // 2. Start recording the publisher
        let recorder = publisher.record()
        
        // 3. Grab the expected result
        let elements = try recorder.elements.get()
        
        // 4. Test the result of the expectation
        XCTAssertEqual(elements, ["Hello", "World!"])
    }
}

就像 wait(for:timeout:) 一样，可以多次调用 get() 方法

class PublisherTests: XCTestCase {
    // SUCCESS: no error
    func testPassthroughSubjectSynchronouslyPublishesElements() throws {
        let publisher = PassthroughSubject<String, Never>()
        let recorder = publisher.record()
        
        publisher.send("foo")
        try XCTAssertEqual(recorder.next().get(), "foo")
        
        publisher.send("bar")
        try XCTAssertEqual(recorder.next().get(), "bar")
    }
}

安装

将 CombineExpectations 的依赖项添加到您的 Swift Package 测试目标

 import PackageDescription
 
 let package = Package(
     dependencies: [
+        .package(url: "https://github.com/groue/CombineExpectations.git", ...)
     ],
     targets: [
         .testTarget(
             dependencies: [
+                "CombineExpectations"
             ])
     ]
 )

发布者期望

有各种发布者期望。 每个都等待特定的发布者方面

availableElements

🕝 recorder.availableElements 等待期望到期，或等待记录的发布者完成。

❌ 在等待此期望时，如果发布者在期望到期之前失败，则会抛出发布者错误。

✅ 否则，返回在期望到期之前发布的所有元素的数组。

➡️ 相关期望：elements、prefix(maxLength)。

与其他期望不同，availableElements 不会在超时到期时使测试失败。 它只会返回到目前为止发布的元素。

例子

// SUCCESS: no timeout, no error
func testTimerPublishesIncreasingDates() throws {
    let publisher = Timer.publish(every: 0.01, on: .main, in: .common).autoconnect()
    let recorder = publisher.record()
    let dates = try wait(for: recorder.availableElements, timeout: ...)
    XCTAssertEqual(dates.sorted(), dates)
}

completion

🕝 recorder.completion 等待记录的发布者完成。

❌ 在等待此期望时，如果发布者未按时完成，则会抛出 RecordingError.notCompleted。

✅ 否则，返回一个 Subscribers.Completion。

➡️ 相关期望：finished、recording。

例子

// SUCCESS: no timeout, no error
func testArrayPublisherCompletesWithSuccess() throws {
    let publisher = ["foo", "bar", "baz"].publisher
    let recorder = publisher.record()
    let completion = try wait(for: recorder.completion, timeout: ...)
    if case let .failure(error) = completion {
        XCTFail("Unexpected error \(error)")
    }
}

// SUCCESS: no error
func testArrayPublisherSynchronouslyCompletesWithSuccess() throws {
    let publisher = ["foo", "bar", "baz"].publisher
    let recorder = publisher.record()
    let completion = try recorder.completion.get()
    if case let .failure(error) = completion {
        XCTFail("Unexpected error \(error)")
    }
}
失败测试的示例 
// FAIL: Asynchronous wait failed
// FAIL: Caught error RecordingError.notCompleted
func testCompletionTimeout() throws {
    let publisher = PassthroughSubject<String, Never>()
    let recorder = publisher.record()
    let completion = try wait(for: recorder.completion, timeout: ...)
}

elements

🕝 recorder.elements 等待记录的发布者完成。

❌ 在等待此期望时，如果发布者未按时完成，则会抛出 RecordingError.notCompleted，如果发布者失败，则会抛出发布者错误。

✅ 否则，返回已发布元素的数组。

➡️ 相关期望：availableElements、last、prefix(maxLength)、recording、single。

例子

// SUCCESS: no timeout, no error
func testArrayPublisherPublishesArrayElements() throws {
    let publisher = ["foo", "bar", "baz"].publisher
    let recorder = publisher.record()
    let elements = try wait(for: recorder.elements, timeout: ...)
    XCTAssertEqual(elements, ["foo", "bar", "baz"])
}

// SUCCESS: no error
func testArrayPublisherSynchronouslyPublishesArrayElements() throws {
    let publisher = ["foo", "bar", "baz"].publisher
    let recorder = publisher.record()
    let elements = try recorder.elements.get()
    XCTAssertEqual(elements, ["foo", "bar", "baz"])
}
失败测试的示例 
// FAIL: Asynchronous wait failed
// FAIL: Caught error RecordingError.notCompleted
func testElementsTimeout() throws {
    let publisher = PassthroughSubject<String, Never>()
    let recorder = publisher.record()
    let elements = try wait(for: recorder.elements, timeout: ...)
}

// FAIL: Caught error MyError
func testElementsError() throws {
    let publisher = PassthroughSubject<String, MyError>()
    let recorder = publisher.record()
    publisher.send(completion: .failure(MyError()))
    let elements = try wait(for: recorder.elements, timeout: ...)
}

finished

🕝 recorder.finished 等待记录的发布者完成。

❌ 在等待此期望时，如果发布者失败，则会抛出发布者错误。

➡️ 相关期望：completion、recording。

例子

// SUCCESS: no timeout, no error
func testArrayPublisherFinishesWithoutError() throws {
    let publisher = ["foo", "bar", "baz"].publisher
    let recorder = publisher.record()
    try wait(for: recorder.finished, timeout: ...)
}

// SUCCESS: no error
func testArrayPublisherSynchronouslyFinishesWithoutError() throws {
    let publisher = ["foo", "bar", "baz"].publisher
    let recorder = publisher.record()
    try recorder.finished.get()
}
失败测试的示例 
// FAIL: Asynchronous wait failed
func testFinishedTimeout() throws {
    let publisher = PassthroughSubject<String, Never>()
    let recorder = publisher.record()
    try wait(for: recorder.finished, timeout: ...)
}

// FAIL: Caught error MyError
func testFinishedError() throws {
    let publisher = PassthroughSubject<String, MyError>()
    let recorder = publisher.record()
    publisher.send(completion: .failure(MyError()))
    try wait(for: recorder.finished, timeout: ...)
}

recorder.finished 可以反转

// SUCCESS: no timeout, no error
func testPassthroughSubjectDoesNotFinish() throws {
    let publisher = PassthroughSubject<String, Never>()
    let recorder = publisher.record()
    try wait(for: recorder.finished.inverted, timeout: ...)
}
失败测试的示例 
// FAIL: Fulfilled inverted expectation
// FAIL: Caught error MyError
func testInvertedFinishedError() throws {
    let publisher = PassthroughSubject<String, MyError>()
    let recorder = publisher.record()
    publisher.send(completion: .failure(MyError()))
    try wait(for: recorder.finished.inverted, timeout: ...)
}

last

🕝 recorder.last 等待记录的发布者完成。

❌ 在等待此期望时，如果发布者未按时完成，则会抛出 RecordingError.notCompleted，如果发布者失败，则会抛出发布者错误。

✅ 否则，返回最后发布的元素；如果发布者在发布任何元素之前完成，则返回 nil。

➡️ 相关期望：elements、single。

例子

// SUCCESS: no timeout, no error
func testArrayPublisherPublishesLastElementLast() throws {
    let publisher = ["foo", "bar", "baz"].publisher
    let recorder = publisher.record()
    if let element = try wait(for: recorder.last, timeout: ...) {
        XCTAssertEqual(element, "baz")
    } else {
        XCTFail("Expected one element")
    }
}

// SUCCESS: no error
func testArrayPublisherSynchronouslyPublishesLastElementLast() throws {
    let publisher = ["foo", "bar", "baz"].publisher
    let recorder = publisher.record()
    if let element = try recorder.last.get() {
        XCTAssertEqual(element, "baz")
    } else {
        XCTFail("Expected one element")
    }
}
失败测试的示例 
// FAIL: Asynchronous wait failed
// FAIL: Caught error RecordingError.notCompleted
func testLastTimeout() throws {
    let publisher = PassthroughSubject<String, Never>()
    let recorder = publisher.record()
    let element = try wait(for: recorder.last, timeout: ...)
}

// FAIL: Caught error MyError
func testLastError() throws {
    let publisher = PassthroughSubject<String, MyError>()
    let recorder = publisher.record()
    publisher.send(completion: .failure(MyError()))
    let element = try wait(for: recorder.last, timeout: ...)
}

next()

🕝 recorder.next() 等待记录的发布者发出一个元素或完成。

❌ 在等待此期望时，如果在上次等待的期望之后发布者未发布一个元素，则会抛出 RecordingError.notEnoughElements。 如果发布者在发布下一个元素之前失败，则会抛出发布者错误。

✅ 否则，返回下一个发布的元素。

➡️ 相关期望：next(count)、single。

例子

// SUCCESS: no timeout, no error
func testArrayOfTwoElementsPublishesElementsInOrder() throws {
    let publisher = ["foo", "bar"].publisher
    let recorder = publisher.record()
    
    var element = try wait(for: recorder.next(), timeout: ...)
    XCTAssertEqual(element, "foo")
    
    element = try wait(for: recorder.next(), timeout: ...)
    XCTAssertEqual(element, "bar")
}

// SUCCESS: no error
func testArrayOfTwoElementsSynchronouslyPublishesElementsInOrder() throws {
    let publisher = ["foo", "bar"].publisher
    let recorder = publisher.record()
    
    var element = try recorder.next().get()
    XCTAssertEqual(element, "foo")
    
    element = try recorder.next().get()
    XCTAssertEqual(element, "bar")
}
失败测试的示例 
// FAIL: Asynchronous wait failed
// FAIL: Caught error RecordingError.notEnoughElements
func testNextTimeout() throws {
    let publisher = PassthroughSubject<String, Never>()
    let recorder = publisher.record()
    let element = try wait(for: recorder.next(), timeout: ...)
}

// FAIL: Caught error MyError
func testNextError() throws {
    let publisher = PassthroughSubject<String, MyError>()
    let recorder = publisher.record()
    publisher.send(completion: .failure(MyError()))
    let element = try wait(for: recorder.next(), timeout: ...)
}

// FAIL: Caught error RecordingError.notEnoughElements
func testNextNotEnoughElementsError() throws {
    let publisher = PassthroughSubject<String, Never>()
    let recorder = publisher.record()
    publisher.send(completion: .finished)
    let element = try wait(for: recorder.next(), timeout: ...)
}

recorder.next() 可以反转

// SUCCESS: no timeout, no error
func testPassthroughSubjectDoesNotPublishAnyElement() throws {
    let publisher = PassthroughSubject<String, Never>()
    let recorder = publisher.record()
    try wait(for: recorder.next().inverted, timeout: ...)
}
失败测试的示例 
// FAIL: Fulfilled inverted expectation
func testInvertedNextTooEarly() throws {
    let publisher = PassthroughSubject<String, Never>()
    let recorder = publisher.record()
    publisher.send("foo")
    try wait(for: recorder.next().inverted, timeout: ...)
}

// FAIL: Fulfilled inverted expectation
// FAIL: Caught error MyError
func testInvertedNextError() throws {
    let publisher = PassthroughSubject<String, MyError>()
    let recorder = publisher.record()
    publisher.send(completion: .failure(MyError()))
    try wait(for: recorder.next().inverted, timeout: ...)
}

next(count)

🕝 recorder.next(count) 等待记录的发布者发出 count 个元素或完成。

❌ 在等待此期望时，如果在上次等待的期望之后发布者未发布 count 个元素，则会抛出 RecordingError.notEnoughElements。 如果发布者在发布下 count 个元素之前失败，则会抛出发布者错误。

✅ 否则，返回一个恰好包含 count 个元素的数组。

➡️ 相关期望：next()、prefix(maxLength)。

例子

// SUCCESS: no timeout, no error
func testArrayOfThreeElementsPublishesTwoThenOneElement() throws {
    let publisher = ["foo", "bar", "baz"].publisher
    let recorder = publisher.record()
    
    var elements = try wait(for: recorder.next(2), timeout: ...)
    XCTAssertEqual(elements, ["foo", "bar"])
    
    elements = try wait(for: recorder.next(1), timeout: ...)
    XCTAssertEqual(elements, ["baz"])
}

// SUCCESS: no error
func testArrayOfThreeElementsSynchronouslyPublishesTwoThenOneElement() throws {
    let publisher = ["foo", "bar", "baz"].publisher
    let recorder = publisher.record()
    
    var elements = try recorder.next(2).get()
    XCTAssertEqual(elements, ["foo", "bar"])
    
    elements = try recorder.next(1).get()
    XCTAssertEqual(elements, ["baz"])
}
失败测试的示例 
// FAIL: Asynchronous wait failed
// FAIL: Caught error RecordingError.notEnoughElements
func testNextCountTimeout() throws {
    let publisher = PassthroughSubject<String, Never>()
    let recorder = publisher.record()
    publisher.send("foo")
    let elements = try wait(for: recorder.next(2), timeout: ...)
}

// FAIL: Caught error MyError
func testNextCountError() throws {
    let publisher = PassthroughSubject<String, MyError>()
    let recorder = publisher.record()
    publisher.send("foo")
    publisher.send(completion: .failure(MyError()))
    let elements = try wait(for: recorder.next(2), timeout: ...)
}

// FAIL: Caught error RecordingError.notEnoughElements
func testNextCountNotEnoughElementsError() throws {
    let publisher = PassthroughSubject<String, Never>()
    let recorder = publisher.record()
    publisher.send("foo")
    publisher.send(completion: .finished)
    let elements = try wait(for: recorder.next(2), timeout: ...)
}

prefix(maxLength)

🕝 recorder.prefix(maxLength) 等待记录的发布者发出 maxLength 个元素或完成。

❌ 在等待此期望时，如果在发布 maxLength 个元素之前发布者失败，则会抛出发布者错误。

✅ 否则，返回一个接收到的元素的数组，最多包含 maxLength 个元素；如果发布者提前完成，则包含的元素较少。

➡️ 相关期望：availableElements、elements、next(count)。

例子

// SUCCESS: no timeout, no error
func testArrayOfThreeElementsPublishesTwoFirstElementsWithoutError() throws {
    let publisher = ["foo", "bar", "baz"].publisher
    let recorder = publisher.record()
    let elements = try wait(for: recorder.prefix(2), timeout: ...)
    XCTAssertEqual(elements, ["foo", "bar"])
}

// SUCCESS: no error
func testArrayOfThreeElementsSynchronouslyPublishesTwoFirstElementsWithoutError() throws {
    let publisher = ["foo", "bar", "baz"].publisher
    let recorder = publisher.record()
    let elements = try recorder.prefix(2).get()
    XCTAssertEqual(elements, ["foo", "bar"])
}
失败测试的示例 
// FAIL: Asynchronous wait failed
func testPrefixTimeout() throws {
    let publisher = PassthroughSubject<String, Never>()
    let recorder = publisher.record()
    publisher.send("foo")
    let elements = try wait(for: recorder.prefix(2), timeout: ...)
}

// FAIL: Caught error MyError
func testPrefixError() throws {
    let publisher = PassthroughSubject<String, MyError>()
    let recorder = publisher.record()
    publisher.send("foo")
    publisher.send(completion: .failure(MyError()))
    let elements = try wait(for: recorder.prefix(2), timeout: ...)
}

recorder.prefix(maxLength) 可以反转

// SUCCESS: no timeout, no error
func testPassthroughSubjectPublishesNoMoreThanSentValues() throws {
    let publisher = PassthroughSubject<String, Never>()
    let recorder = publisher.record()
    publisher.send("foo")
    publisher.send("bar")
    let elements = try wait(for: recorder.prefix(3).inverted, timeout: ...)
    XCTAssertEqual(elements, ["foo", "bar"])
}
失败测试的示例 
// FAIL: Fulfilled inverted expectation
func testInvertedPrefixTooEarly() throws {
    let publisher = PassthroughSubject<String, Never>()
    let recorder = publisher.record()
    publisher.send("foo")
    publisher.send("bar")
    publisher.send("baz")
    let elements = try wait(for: recorder.prefix(3).inverted, timeout: ...)
}

// FAIL: Fulfilled inverted expectation
// FAIL: Caught error MyError
func testInvertedPrefixError() throws {
    let publisher = PassthroughSubject<String, MyError>()
    let recorder = publisher.record()
    publisher.send("foo")
    publisher.send(completion: .failure(MyError()))
    let elements = try wait(for: recorder.prefix(3).inverted, timeout: ...)
}

recording

🕝 recorder.recording 等待记录的发布者完成。

❌ 在等待此期望时，如果发布者未按时完成，则会抛出 RecordingError.notCompleted。

✅ 否则，返回一个 Record.Recording。

➡️ 相关期望：completion、elements、finished。

例子

// SUCCESS: no timeout, no error
func testArrayPublisherRecording() throws {
    let publisher = ["foo", "bar", "baz"].publisher
    let recorder = publisher.record()
    let recording = try wait(for: recorder.recording, timeout: ...)
    XCTAssertEqual(recording.output, ["foo", "bar", "baz"])
    if case let .failure(error) = recording.completion {
        XCTFail("Unexpected error \(error)")
    }
}

// SUCCESS: no error
func testArrayPublisherSynchronousRecording() throws {
    let publisher = ["foo", "bar", "baz"].publisher
    let recorder = publisher.record()
    let recording = try recorder.recording.get()
    XCTAssertEqual(recording.output, ["foo", "bar", "baz"])
    if case let .failure(error) = recording.completion {
        XCTFail("Unexpected error \(error)")
    }
}
失败测试的示例 
// FAIL: Asynchronous wait failed
// FAIL: Caught error RecordingError.notCompleted
func testRecordingTimeout() throws {
    let publisher = PassthroughSubject<String, Never>()
    let recorder = publisher.record()
    let recording = try wait(for: recorder.recording, timeout: ...)
}

single

🕝 recorder.single 等待记录的发布者完成。

❌ 在等待此期望时，如果发布者未按时完成，或者在完成之前未发布恰好一个元素，则会抛出 RecordingError。 如果发布者失败，则会抛出发布者错误。

✅ 否则，返回单个发布的元素。

➡️ 相关期望：elements、last、next()。

例子

// SUCCESS: no timeout, no error
func testJustPublishesExactlyOneElement() throws {
    let publisher = Just("foo")
    let recorder = publisher.record()
    let element = try wait(for: recorder.single, timeout: ...)
    XCTAssertEqual(element, "foo")
}

// SUCCESS: no error
func testJustSynchronouslyPublishesExactlyOneElement() throws {
    let publisher = Just("foo")
    let recorder = publisher.record()
    let element = try recorder.single.get()
    XCTAssertEqual(element, "foo")
}
失败测试的示例 
// FAIL: Asynchronous wait failed
// FAIL: Caught error RecordingError.notCompleted
func testSingleTimeout() throws {
    let publisher = PassthroughSubject<String, Never>()
    let recorder = publisher.record()
    let element = try wait(for: recorder.single, timeout: ...)
}

// FAIL: Caught error MyError
func testSingleError() throws {
    let publisher = PassthroughSubject<String, MyError>()
    let recorder = publisher.record()
    publisher.send(completion: .failure(MyError()))
    let element = try wait(for: recorder.single, timeout: ...)
}

// FAIL: Caught error RecordingError.tooManyElements
func testSingleTooManyElementsError() throws {
    let publisher = PassthroughSubject<String, Never>()
    let recorder = publisher.record()
    publisher.send("foo")
    publisher.send("bar")
    publisher.send(completion: .finished)
    let element = try wait(for: recorder.single, timeout: ...)
}

// FAIL: Caught error RecordingError.notEnoughElements
func testSingleNotEnoughElementsError() throws {
    let publisher = PassthroughSubject<String, Never>()
    let recorder = publisher.record()
    publisher.send(completion: .finished)
    let element = try wait(for: recorder.single, timeout: ...)
}