Test throttled session

Tests/ProcessOutTests/Sources/Unit/Sessions/WebAuthentication/ThrottledWebAuthenticationSessionDecoratorTests.swift

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+//
+//  ThrottledWebAuthenticationSessionDecoratorTests.swift
+//  ProcessOut
+//
+//  Created by Andrii Vysotskyi on 10.10.2024.
+//
+
+@testable import ProcessOut
+import XCTest
+
+final class ThrottledWebAuthenticationSessionDecoratorTests: XCTestCase {
+
+    // MARK: - Wait
+
+    func test_authenticate_allowsOneAuthenticationAtTime() async throws {
+        // Given
+        let mockSession = MockWebAuthenticationSession()
+        mockSession.authenticateFromClosure = { _, _, _ in
+            try await Task.sleep(for: .seconds(5))
+            return URL(string: "response.com")!
+        }
+        let sut = ThrottledWebAuthenticationSessionDecorator(session: mockSession)
+
+        // When
+        Task {
+            _ = try await sut.authenticate(using: URL(string: "request1.com")!)
+        }
+        Task {
+            _ = try await sut.authenticate(using: URL(string: "request2.com")!)
+        }
+        try await Task.sleep(for: .seconds(1))
+
+        // Then
+        XCTAssertEqual(mockSession.authenticateCallsCount, 1)
+    }
+
+    func test_authenticate_throttlesAuthentications() async throws {
+        var lastAuthenticationStartTime: DispatchTime?
+
+        // Given
+        let mockSession = MockWebAuthenticationSession()
+        mockSession.authenticateFromClosure = { _, _, _ in
+            // Then
+            if let lastAuthenticationStartTime {
+                let delay = Int(DispatchTime.now().uptimeNanoseconds - lastAuthenticationStartTime.uptimeNanoseconds)
+                let expectedDelay = 1_000_000_000, tolerance = 500_000_000 // 1 and 0.5 seconds respectfully
+                XCTAssertTrue(abs(delay - expectedDelay) <= tolerance)
+            }
+            lastAuthenticationStartTime = DispatchTime.now()
+            return URL(string: "response.com")!
+        }
+        let sut = ThrottledWebAuthenticationSessionDecorator(session: mockSession)
+
+        // When
+        _ = try await sut.authenticate(using: URL(string: "request1.com")!)
+        _ = try await sut.authenticate(using: URL(string: "request2.com")!)
+    }
+}