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OR-5253 TransformingOperators:: flatMap #82

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merged 1 commit into from
Jul 9, 2023
Merged

OR-5253 TransformingOperators:: flatMap #82

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4 changes: 4 additions & 0 deletions CombineDemo/CombineDemo.xcodeproj/project.pbxproj
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Expand Up @@ -24,6 +24,7 @@
96321F052A5AA32200C60D8A /* CollectTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 96321F042A5AA32200C60D8A /* CollectTests.swift */; };
96321F072A5AACA400C60D8A /* MapTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 96321F062A5AACA400C60D8A /* MapTests.swift */; };
96321F092A5AB41200C60D8A /* MapKeypathTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 96321F082A5AB41200C60D8A /* MapKeypathTests.swift */; };
9638B7B52A5ABDEF005F01A0 /* FlatMapTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 9638B7B42A5ABDEF005F01A0 /* FlatMapTests.swift */; };
9642B75129D2130500CB89C8 /* CombineDemoApp.swift in Sources */ = {isa = PBXBuildFile; fileRef = 9642B75029D2130500CB89C8 /* CombineDemoApp.swift */; };
9642B75329D2130500CB89C8 /* ContentView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 9642B75229D2130500CB89C8 /* ContentView.swift */; };
9642B75529D2130600CB89C8 /* Assets.xcassets in Resources */ = {isa = PBXBuildFile; fileRef = 9642B75429D2130600CB89C8 /* Assets.xcassets */; };
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96321F042A5AA32200C60D8A /* CollectTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CollectTests.swift; sourceTree = "<group>"; };
96321F062A5AACA400C60D8A /* MapTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MapTests.swift; sourceTree = "<group>"; };
96321F082A5AB41200C60D8A /* MapKeypathTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MapKeypathTests.swift; sourceTree = "<group>"; };
9638B7B42A5ABDEF005F01A0 /* FlatMapTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = FlatMapTests.swift; sourceTree = "<group>"; };
9642B74D29D2130500CB89C8 /* CombineDemo.app */ = {isa = PBXFileReference; explicitFileType = wrapper.application; includeInIndex = 0; path = CombineDemo.app; sourceTree = BUILT_PRODUCTS_DIR; };
9642B75029D2130500CB89C8 /* CombineDemoApp.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CombineDemoApp.swift; sourceTree = "<group>"; };
9642B75229D2130500CB89C8 /* ContentView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ContentView.swift; sourceTree = "<group>"; };
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96321F062A5AACA400C60D8A /* MapTests.swift */,
96321F082A5AB41200C60D8A /* MapKeypathTests.swift */,
9609DCF32A5AB7E500A3B065 /* TryMapTests.swift */,
9638B7B42A5ABDEF005F01A0 /* FlatMapTests.swift */,
);
path = TransformingOperators;
sourceTree = "<group>";
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9631D29C29DA736200A9D790 /* NotificationTests.swift in Sources */,
9631D2EA29E657D500A9D790 /* IntSubscriberTests.swift in Sources */,
9609DCF42A5AB7E500A3B065 /* TryMapTests.swift in Sources */,
9638B7B52A5ABDEF005F01A0 /* FlatMapTests.swift in Sources */,
96321F092A5AB41200C60D8A /* MapKeypathTests.swift in Sources */,
9642B78329D28DEA00CB89C8 /* DispatchQueueType.swift in Sources */,
9631D29E29DB503900A9D790 /* URLSessionTests.swift in Sources */,
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194 changes: 194 additions & 0 deletions CombineDemo/CombineDemoTests/Operators/TransformingOperators/FlatMapTests.swift
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//
// FlatMapTests.swift
// CombineDemoTests
//
// Created by Manish Rathi on 09/07/2023.
//

import Foundation
import Combine
import XCTest

/// - `flatMap(maxPublishers:_:)` Transforms all elements from an upstream publisher into a new publisher up to a maximum number of publishers you specify.
/// - https://developer.apple.com/documentation/combine/publishers/collect/flatmap(maxpublishers:_:)-36djm
final class FlatMapTests: XCTestCase {
var cancellables: Set<AnyCancellable>!
var isFinishedCalled: Bool!
var receivedValues: [String]!

override func setUp() {
super.setUp()

cancellables = []
isFinishedCalled = false
receivedValues = []
}

override func tearDown() {
cancellables = nil
isFinishedCalled = nil
receivedValues = []

super.tearDown()
}

func testPublisherWithoutFlatMapOperator() {
let firstMessenger = Messenger(name: "No:1", message: "Hi, i am no:1")

// Given: Publisher
let chatPublisher = CurrentValueSubject<Messenger, Never>(firstMessenger)

// When: Sink(Subscription)
chatPublisher
.sink { [weak self] completion in
switch completion {
case .finished:
self?.isFinishedCalled = true
}
} receiveValue: { [weak self] messenger in
self?.receivedValues.append(messenger.message.value)
}
.store(in: &cancellables)

// Then: Receiving correct value
XCTAssertFalse(isFinishedCalled)
XCTAssertEqual(receivedValues, ["Hi, i am no:1"])
}

func testPublisherWithoutFlatMapOperatorScenario2() {
let firstMessenger = Messenger(name: "No:1", message: "Hi, i am no:1")
let secondMessenger = Messenger(name: "No:2", message: "Hi, i am no:2")

// Given: Publisher
let chatPublisher = CurrentValueSubject<Messenger, Never>(firstMessenger)

// When: Sink(Subscription)
chatPublisher
.sink { [weak self] completion in
switch completion {
case .finished:
self?.isFinishedCalled = true
}
} receiveValue: { [weak self] messenger in
self?.receivedValues.append(messenger.message.value)
}
.store(in: &cancellables)

// When:
firstMessenger.message.value = "No:1 has changed message" // This is nested Publisher and is not received
chatPublisher.value = secondMessenger

// Then: Receiving correct value
XCTAssertFalse(isFinishedCalled)
XCTAssertEqual(receivedValues, ["Hi, i am no:1", "Hi, i am no:2"])
}

func testPublisherWithFlatMapOperator() {
let firstMessenger = Messenger(name: "No:1", message: "Hi, i am no:1")
let secondMessenger = Messenger(name: "No:2", message: "Hi, i am no:2")

// Given: Publisher
let chatPublisher = CurrentValueSubject<Messenger, Never>(firstMessenger)

// When: Sink(Subscription)
chatPublisher
.flatMap{ $0.message }
.sink { [weak self] completion in
switch completion {
case .finished:
self?.isFinishedCalled = true
}
} receiveValue: { [weak self] value in
self?.receivedValues.append(value)
}
.store(in: &cancellables)

// When:
firstMessenger.message.value = "No:1 has changed message" // This is nested Publisher and will receive because of flatMap
chatPublisher.value = secondMessenger

// Then: Receiving correct value
XCTAssertFalse(isFinishedCalled)
XCTAssertEqual(receivedValues, ["Hi, i am no:1", "No:1 has changed message", "Hi, i am no:2"])
}

func testPublisherWithFlatMapOperatorScenario2() {
let firstMessenger = Messenger(name: "No:1", message: "Hi, i am no:1")
let secondMessenger = Messenger(name: "No:2", message: "Hi, i am no:2")

// Given: Publisher
let chatPublisher = CurrentValueSubject<Messenger, Never>(firstMessenger)

// When: Sink(Subscription)
chatPublisher
.flatMap{ $0.message }
.sink { [weak self] completion in
switch completion {
case .finished:
self?.isFinishedCalled = true
}
} receiveValue: { [weak self] value in
self?.receivedValues.append(value)
}
.store(in: &cancellables)

// When:
firstMessenger.message.value = "No:1 has changed message" // This is nested Publisher and will receive because of flatMap
chatPublisher.value = secondMessenger

firstMessenger.message.value = "No:1 has changed message again"
secondMessenger.message.value = "No:2 has changed message too"

// Then: Receiving correct value
XCTAssertFalse(isFinishedCalled)
XCTAssertEqual(receivedValues, ["Hi, i am no:1", "No:1 has changed message", "Hi, i am no:2", "No:1 has changed message again", "No:2 has changed message too"])
}

func testPublisherWithFlatMapOperatorScenario3() {
let firstMessenger = Messenger(name: "No:1", message: "Hi, i am no:1")
let secondMessenger = Messenger(name: "No:2", message: "Hi, i am no:2")
let thirdMessenger = Messenger(name: "No:3", message: "Hi, i am no:3")

// Given: Publisher
let chatPublisher = CurrentValueSubject<Messenger, Never>(firstMessenger)

// When: Sink(Subscription)
chatPublisher
.flatMap(maxPublishers: .max(2)) { $0.message } // Adding here maximum two publishers (thirdMessenger will ignored)
.sink { [weak self] completion in
switch completion {
case .finished:
self?.isFinishedCalled = true
}
} receiveValue: { [weak self] value in
self?.receivedValues.append(value)
}
.store(in: &cancellables)

// When:
firstMessenger.message.value = "No:1 has changed message" // This is nested Publisher and will receive because of flatMap
chatPublisher.value = secondMessenger

firstMessenger.message.value = "No:1 has changed message again"
secondMessenger.message.value = "No:2 has changed message too"

chatPublisher.value = thirdMessenger // Let's try 3rd messenger
firstMessenger.message.value = "No:1 did not hear about No:3"
secondMessenger.message.value = "No:2 also did not receive the No:3 message"


// Then: Receiving correct value
XCTAssertFalse(isFinishedCalled)
XCTAssertEqual(receivedValues, ["Hi, i am no:1", "No:1 has changed message", "Hi, i am no:2", "No:1 has changed message again", "No:2 has changed message too", "No:1 did not hear about No:3", "No:2 also did not receive the No:3 message"])
}
}

struct Messenger {
let name: String
let message: CurrentValueSubject<String, Never>

init(name: String, message: String) {
self.name = name
self.message = CurrentValueSubject(message)
}
}
2 changes: 1 addition & 1 deletion README.md
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- `map value` https://github.com/crazymanish/what-matters-most/pull/79
- `map keypath value` https://github.com/crazymanish/what-matters-most/pull/80
- `tryMap value` https://github.com/crazymanish/what-matters-most/pull/81
- [ ] Flattening publishers
- [x] Flattening publishers https://github.com/crazymanish/what-matters-most/pull/82
- [ ] Replacing/transforming upstream output
- [ ] Practices
- [ ] Filtering Operators
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