[Tech] Publisher: Add global mock and XCTTest

core/Unit-tests/Classes/Publisher/PublisherMock.swift

@@ -0,0 +1,55 @@
+//
+//  PublisherMock.swift
+//  Spark
+//
+//  Created by robin.lemaire on 31/08/2023.
+//  Copyright © 2023 Adevinta. All rights reserved.
+//
+
+import Combine
+import Foundation
+
+final class PublisherMock<T: Publisher> {
+
+    // MARK: - Properties
+
+    private let publisher: T
+    let name: String
+    var sinkValue: T.Output?
+    var sinkValues = [T.Output]()
+    var sinkCount = 0
+    var sinkCalled: Bool {
+        return self.sinkCount > 0
+    }
+
+    // MARK: - Initialization
+
+    init(
+        publisher: T,
+        name: String = String(describing: T.Output.self)
+    ) {
+        self.publisher = publisher
+        self.name = name
+    }
+
+    // MARK: - Methods
+
+    func reset() {
+        self.sinkValue = nil
+        self.sinkValues.removeAll()
+        self.sinkCount = 0
+    }
+}
+
+// MARK: - Tests Management
+
+extension PublisherMock where T.Failure == Never {
+
+    func loadTesting(on subscriptions: inout Set<AnyCancellable>) {
+        self.publisher.sink { value in
+            self.sinkValue = value
+            self.sinkValues.append(value)
+            self.sinkCount += 1
+        }.store(in: &subscriptions)
+    }
+}

core/Unit-tests/Classes/Publisher/XCTest+PublisherMock.swift

@@ -0,0 +1,94 @@
+//
+//  XCTest+PublisherMock.swift
+//  SparkCoreTests
+//
+//  Created by robin.lemaire on 04/09/2023.
+//  Copyright © 2023 Adevinta. All rights reserved.
+//
+
+import XCTest
+import Combine
+
+extension XCTest {
+
+    // MARK: - Tests
+
+    func XCTAssertPublisherSinkCountEqual<T: Publisher>(
+        on mock: PublisherMock<T>,
+        _ expression: Int
+    ) {
+        XCTAssertEqual(
+            mock.sinkCount,
+            expression,
+            Self.errorMessage(on: mock, for: .count)
+        )
+    }
+
+    func XCTAssertPublisherSinkIsCalled<T: Publisher>(
+        on mock: PublisherMock<T>,
+        _ expression: Bool
+    ) {
+        XCTAssertEqual(
+            mock.sinkCalled,
+            expression,
+            Self.errorMessage(on: mock, for: .isCalled)
+        )
+    }
+
+    func XCTAssertPublisherSinkValueEqual<T: Publisher>(
+        on mock: PublisherMock<T>,
+        _ expression: T.Output
+    ) where T.Output: Equatable {
+        XCTAssertEqual(
+            mock.sinkValue,
+            expression,
+            Self.errorMessage(on: mock, for: .value)
+        )
+    }
+
+    func XCTAssertPublisherSinkValueIdentical<T: Publisher, Z: AnyObject>(
+        on mock: PublisherMock<T>,
+        _ expression: Z?,
+        expressionShouldBeSet: Bool = true
+    ) {
+        guard (expressionShouldBeSet && expression != nil) || !expressionShouldBeSet else {
+            XCTFail("\(Z.self) expression should be set")
+            return
+        }
+
+        XCTAssertIdentical(
+            mock.sinkValue as? Z,
+            expression,
+            Self.errorMessage(on: mock, for: .value)
+        )
+    }
+
+    func XCTAssertPublisherSinkValuesEqual<T: Publisher>(
+        on mock: PublisherMock<T>,
+        _ expression: [T.Output]
+    ) where T.Output: Equatable {
+        XCTAssertEqual(
+            mock.sinkValues,
+            expression,
+            Self.errorMessage(on: mock, for: .values)
+        )
+    }
+
+    // MARK: - Test Type
+
+    private enum TestingSinkType: String {
+        case count
+        case isCalled
+        case value
+        case values
+    }
+
+    // MARK: - Message
+
+    private static func errorMessage<T: Publisher>(
+        on mock: PublisherMock<T>,
+        for type: TestingSinkType
+    ) -> String {
+        return "Wrong \(mock.name) sink \(type.rawValue) value"
+    }
+}