111 lines
4.6 KiB
Swift
111 lines
4.6 KiB
Swift
#if canImport(Combine)
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import XCTest
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@available(iOS 13, macOS 10.15, tvOS 13, watchOS 6, *)
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extension PublisherExpectations {
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/// A publisher expectation which waits for the recorded publisher to emit
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/// `maxLength` elements, or to complete.
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///
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/// When waiting for this expectation, the publisher error is thrown if the
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/// publisher fails before `maxLength` elements are published.
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///
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/// Otherwise, an array of received elements is returned, containing at
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/// most `maxLength` elements, or less if the publisher completes early.
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///
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/// For example:
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///
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/// // SUCCESS: no timeout, no error
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/// func testArrayOfThreeElementsPublishesTwoFirstElementsWithoutError() throws {
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/// let publisher = ["foo", "bar", "baz"].publisher
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/// let recorder = publisher.record()
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/// let elements = try wait(for: recorder.prefix(2), timeout: 1)
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/// XCTAssertEqual(elements, ["foo", "bar"])
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/// }
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///
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/// This publisher expectation can be inverted:
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///
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/// // SUCCESS: no timeout, no error
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/// func testPassthroughSubjectPublishesNoMoreThanSentValues() throws {
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/// let publisher = PassthroughSubject<String, Never>()
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/// let recorder = publisher.record()
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/// publisher.send("foo")
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/// publisher.send("bar")
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/// let elements = try wait(for: recorder.prefix(3).inverted, timeout: 1)
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/// XCTAssertEqual(elements, ["foo", "bar"])
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/// }
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public struct Prefix<Input, Failure: Error>: PublisherExpectation {
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let recorder: Recorder<Input, Failure>
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let maxLength: Int
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init(recorder: Recorder<Input, Failure>, maxLength: Int) {
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precondition(maxLength >= 0, "Can't take a prefix of negative length")
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self.recorder = recorder
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self.maxLength = maxLength
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}
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public func _setup(_ expectation: XCTestExpectation) {
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if maxLength == 0 {
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// Such an expectation is immediately fulfilled, by essence.
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expectation.expectedFulfillmentCount = 1
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expectation.fulfill()
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} else {
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expectation.expectedFulfillmentCount = maxLength
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recorder.fulfillOnInput(expectation, includingConsumed: true)
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}
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}
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/// Returns the expected output, or throws an error if the
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/// expectation fails.
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///
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/// For example:
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///
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/// // SUCCESS: no error
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/// func testArrayOfThreeElementsSynchronouslyPublishesTwoFirstElementsWithoutError() throws {
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/// let publisher = ["foo", "bar", "baz"].publisher
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/// let recorder = publisher.record()
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/// let elements = try recorder.prefix(2).get()
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/// XCTAssertEqual(elements, ["foo", "bar"])
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/// }
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public func get() throws -> [Input] {
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try recorder.value { (elements, completion, remainingElements, consume) in
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if elements.count >= maxLength {
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let extraCount = max(maxLength + remainingElements.count - elements.count, 0)
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consume(extraCount)
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return Array(elements.prefix(maxLength))
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}
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if case let .failure(error) = completion {
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throw error
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}
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consume(remainingElements.count)
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return elements
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}
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}
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/// Returns an inverted publisher expectation which waits for a
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/// publisher to emit `maxLength` elements, or to complete.
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///
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/// When waiting for this expectation, the publisher error is thrown
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/// if the publisher fails before `maxLength` elements are published.
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///
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/// Otherwise, an array of received elements is returned, containing at
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/// most `maxLength` elements, or less if the publisher completes early.
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///
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/// For example:
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///
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/// // SUCCESS: no timeout, no error
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/// func testPassthroughSubjectPublishesNoMoreThanSentValues() throws {
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/// let publisher = PassthroughSubject<String, Never>()
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/// let recorder = publisher.record()
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/// publisher.send("foo")
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/// publisher.send("bar")
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/// let elements = try wait(for: recorder.prefix(3).inverted, timeout: 1)
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/// XCTAssertEqual(elements, ["foo", "bar"])
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/// }
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public var inverted: Inverted<Self> {
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return Inverted(base: self)
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}
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}
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}
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#endif
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