79 lines
3.0 KiB
Swift
79 lines
3.0 KiB
Swift
//
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// OperatorTestHelper.swift
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//
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//
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// Created by Joseph Spadafora on 7/6/19.
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//
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import XCTest
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#if OPENCOMBINE_COMPATIBILITY_TEST
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import Combine
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#else
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import OpenCombine
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#endif
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/// `OperatorTestHelper` is an abstraction that helps avoid a lot of boilerplate when
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/// testing an operator. It is initialized with a publisher type and creates a
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/// `CustomSubscription`, `CustomPublisherBase` and `TrackingSubscriberBase`.
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@available(macOS 10.15, iOS 13.0, *)
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class OperatorTestHelper<SourceValue,
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SourceError: Error,
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SourcePublisher,
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Sut: Publisher>
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where SourcePublisher: CustomPublisherBase<SourceValue, SourceError>
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{
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typealias Value = Sut.Output
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typealias Failure = Sut.Failure
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let subscription: CustomSubscription
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let publisher: SourcePublisher
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let tracking: TrackingSubscriberBase<Value, Failure>
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private(set) var sut: Sut
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var downstreamSubscription: Subscription?
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/// This initializes the `OperatorTestHelper`. In most cases,
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/// you can just pass a `publisherType` and closure
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/// for `createSut` to get all the setup that you'll need for a test.
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/// - Parameter publisherType: This should be filled in with the
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/// type of `CustomPublisherBase` that you would like the
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/// operator you are testing to be built from.
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/// - Parameter initialDemand: This is the demand that the
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/// created `TrackingSubscriber` should return upon receiving a subscription.
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/// - Parameter receiveValueDemand: This is the demand that the
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/// created `TrackingSubscriber should return upon receiving a value.
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/// - Parameter customSubscription: This parameter defaults to `CustomSubscription()`,
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/// but can be replaced with your own instance if you want to override
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/// any of the default `CustomSubscription` initializer closures.
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/// - Parameter createSut: This closure takes a new concrete instance
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/// of the `publisherType` as an input to the closure and creates an
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/// instance of the operator that you are trying to test.
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init(publisherType: SourcePublisher.Type,
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initialDemand: Subscribers.Demand?,
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receiveValueDemand: Subscribers.Demand,
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customSubscription: CustomSubscription = CustomSubscription(),
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createSut: (SourcePublisher) -> Sut)
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{
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self.subscription = customSubscription
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let createdPublisher = publisherType.init(subscription: customSubscription)
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self.publisher = createdPublisher
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self.sut = createSut(createdPublisher)
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self.tracking = TrackingSubscriberBase<Value, Failure>(
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receiveSubscription: {
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initialDemand.map($0.request)
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},
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receiveValue: { _ in receiveValueDemand }
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)
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tracking.onSubscribe = { [weak self] in
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self?.downstreamSubscription = $0
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}
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sut.subscribe(tracking)
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}
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deinit {
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downstreamSubscription?.cancel()
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tracking.cancel()
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}
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}
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