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OR-5257 FilteringOperators::
Dropping values (#92)
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CombineDemo/CombineDemoTests/Operators/FilteringOperators/DroppingValuesTests.swift
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,206 @@ | ||
| // | ||
| // DroppingValuesTests.swift | ||
| // CombineDemoTests | ||
| // | ||
| // Created by Manish Rathi on 09/07/2023. | ||
| // | ||
|
|
||
| import Foundation | ||
| import Combine | ||
| import XCTest | ||
|
|
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| /// - We can use it when we want to ignore values from one publisher until a second one starts publishing, | ||
| /// - or if we want to ignore a specific amount of values at the start of the stream. | ||
| /// | ||
| /// - `dropFirst(_:)` Omits the specified number of elements before republishing subsequent elements. | ||
| /// - https://developer.apple.com/documentation/combine/publishers/collect/dropfirst(_:) | ||
| /// - `drop(while:)` Omits elements from the upstream publisher until a given closure returns false, before republishing all remaining elements. | ||
| /// - https://developer.apple.com/documentation/combine/publishers/collect/drop(while:) | ||
| /// - `tryDrop(while:)` Omits elements from the upstream publisher until an error-throwing closure returns false, before republishing all remaining elements. | ||
| /// - https://developer.apple.com/documentation/combine/publishers/collect/trydrop(while:) | ||
| /// - `drop(untilOutputFrom:)` Ignores elements from the upstream publisher until it receives an element from a second publisher. | ||
| /// - https://developer.apple.com/documentation/combine/publishers/collect/drop(untiloutputfrom:) | ||
| final class DroppingValuesTests: XCTestCase { | ||
| var publisher: Publishers.Sequence<ClosedRange<Int>, Never>! | ||
| var cancellables: Set<AnyCancellable>! | ||
| var isFinishedCalled: Bool! | ||
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|
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| override func setUp() { | ||
| super.setUp() | ||
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| publisher = (1...10).publisher | ||
| cancellables = [] | ||
| isFinishedCalled = false | ||
| } | ||
|
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| override func tearDown() { | ||
| publisher = nil | ||
| cancellables = nil | ||
| isFinishedCalled = nil | ||
|
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| super.tearDown() | ||
| } | ||
|
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| func testPublisherWithDropFirstOperator() { | ||
| // Given: Publisher | ||
| // publisher = (1...10).publisher | ||
| var receivedValues: [Int] = [] | ||
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| // When: Sink(Subscription) | ||
| publisher | ||
| .dropFirst() | ||
| .sink { [weak self] completion in | ||
| switch completion { | ||
| case .finished: | ||
| self?.isFinishedCalled = true | ||
| } | ||
| } receiveValue: { value in | ||
| receivedValues.append(value) | ||
| } | ||
| .store(in: &cancellables) | ||
|
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||
| // Then: Receiving correct value | ||
| XCTAssertTrue(isFinishedCalled) | ||
| XCTAssertEqual(receivedValues, [2, 3, 4, 5, 6, 7, 8, 9, 10]) // drop (first) | ||
| } | ||
|
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| func testPublisherWithDropFirstWithSpecificCountOperator() { | ||
| // Given: Publisher | ||
| // publisher = (1...10).publisher | ||
| var receivedValues: [Int] = [] | ||
|
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| // When: Sink(Subscription) | ||
| publisher | ||
| .dropFirst(6) | ||
| .sink { [weak self] completion in | ||
| switch completion { | ||
| case .finished: | ||
| self?.isFinishedCalled = true | ||
| } | ||
| } receiveValue: { value in | ||
| receivedValues.append(value) | ||
| } | ||
| .store(in: &cancellables) | ||
|
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| // Then: Receiving correct value | ||
| XCTAssertTrue(isFinishedCalled) | ||
| XCTAssertEqual(receivedValues, [7, 8, 9, 10]) // drop (first) 6 elements | ||
| } | ||
|
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| func testPublisherWithDropWhileOperator() { | ||
| // Given: Publisher | ||
| // publisher = (1...10).publisher | ||
| var receivedValues: [Int] = [] | ||
|
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| // When: Sink(Subscription) | ||
| publisher | ||
| .drop(while: { $0 % 3 != 0 }) | ||
| .sink { [weak self] completion in | ||
| switch completion { | ||
| case .finished: | ||
| self?.isFinishedCalled = true | ||
| } | ||
| } receiveValue: { value in | ||
| receivedValues.append(value) | ||
| } | ||
| .store(in: &cancellables) | ||
|
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| // Then: Receiving correct value | ||
| XCTAssertTrue(isFinishedCalled) | ||
| XCTAssertEqual(receivedValues, [3, 4, 5, 6, 7, 8, 9, 10]) // drop (while) [elements % 3 != 0] | ||
| } | ||
|
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| func testPublisherWithTryDropWhileOperator() { | ||
| // Given: Publisher | ||
| let publisher = [1, 2, 3, 4, 5, 6, -1, 7, 8, 9, 10].publisher | ||
| let range: CountableClosedRange<Int> = (1...100) | ||
| var receivedValues: [Int] = [] | ||
| var receivedError: ApiError? | ||
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| // When: Sink(Subscription) | ||
| publisher | ||
| .tryDrop { | ||
| guard $0 != 0 else { throw ApiError(code: .notFound) } | ||
| return range.contains($0) | ||
| } | ||
| .sink { [weak self] completion in | ||
| switch completion { | ||
| case .finished: | ||
| self?.isFinishedCalled = true | ||
| case .failure(let error): | ||
| receivedError = error as? ApiError | ||
| } | ||
| } receiveValue: { value in | ||
| receivedValues.append(value) | ||
| } | ||
| .store(in: &cancellables) | ||
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| // Then: Receiving correct value | ||
| XCTAssertTrue(isFinishedCalled) // Successful finished | ||
| XCTAssertEqual(receivedValues, [-1, 7, 8, 9, 10]) | ||
| XCTAssertNil(receivedError) | ||
| } | ||
|
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| func testPublisherWithTryDropWhileOperatorScenario2() { | ||
| // Given: Publisher | ||
| let publisher = [1, 2, 3, 4, 5, 6, 0, -1, 7, 8, 9, 10].publisher | ||
| let range: CountableClosedRange<Int> = (1...100) | ||
| var receivedValues: [Int] = [] | ||
| var receivedError: ApiError? | ||
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| // When: Sink(Subscription) | ||
| publisher | ||
| .tryDrop { | ||
| guard $0 != 0 else { throw ApiError(code: .notFound) } | ||
| return range.contains($0) | ||
| } | ||
| .sink { [weak self] completion in | ||
| switch completion { | ||
| case .finished: | ||
| self?.isFinishedCalled = true | ||
| case .failure(let error): | ||
| receivedError = error as? ApiError | ||
| } | ||
| } receiveValue: { value in | ||
| receivedValues.append(value) | ||
| } | ||
| .store(in: &cancellables) | ||
|
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| // Then: Receiving correct value | ||
| XCTAssertFalse(isFinishedCalled) // Successful finished not called, because it is finished with error | ||
| XCTAssertEqual(receivedValues, []) // Nothing received because of error | ||
| XCTAssertEqual(receivedError?.code, .notFound) // Finished with correct error | ||
| } | ||
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| func testPublisherWithTryDropUntilOutputFromOperator() { | ||
| // Given: Publisher | ||
| let firstPublisher = PassthroughSubject<Int,Never>() | ||
| let secondPublisher = PassthroughSubject<String,Never>() | ||
| var receivedValues: [Int] = [] | ||
|
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| // When: Sink(Subscription) | ||
| firstPublisher | ||
| .drop(untilOutputFrom: secondPublisher) | ||
| .sink { [weak self] completion in | ||
| switch completion { | ||
| case .finished: | ||
| self?.isFinishedCalled = true | ||
| } | ||
| } receiveValue: { value in | ||
| receivedValues.append(value) | ||
| } | ||
| .store(in: &cancellables) | ||
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| // It will drop all values of firstPublisher, until secondPublisher kicks-in | ||
| firstPublisher.send(1) | ||
| firstPublisher.send(2) | ||
| secondPublisher.send("This will kick-off the firstPublisher") | ||
| firstPublisher.send(3) | ||
| firstPublisher.send(4) | ||
| firstPublisher.send(completion: .finished) | ||
|
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| // Then: Receiving correct value | ||
| XCTAssertTrue(isFinishedCalled) // Successful finished | ||
| XCTAssertEqual(receivedValues, [3, 4]) // Received values only after the secondPublisher's output | ||
| } | ||
| } |
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