Implement RefundRequestProvider tests

Tests/FlareTests/UnitTests/Providers/RefundRequestProviderTests.swift

@@ -0,0 +1,61 @@
+//
+// Flare
+// Copyright © 2023 Space Code. All rights reserved.
+//
+
+@testable import Flare
+import XCTest
+
+#if os(iOS) || VISION_OS
+
+    @available(iOS 15.0, *)
+    final class RefundRequestProviderTests: XCTestCase {
+        // MARK: Proeprties
+
+        private var sut: RefundRequestProvider!
+
+        // MARK: XCTestCase
+
+        override func setUp() {
+            super.setUp()
+            sut = RefundRequestProvider()
+        }
+
+        override func tearDown() {
+            sut = nil
+            super.tearDown()
+        }
+
+        // MARK: Tests
+
+        @MainActor
+        func test_thatRefundRequestProviderThrowsAnUnknownError_whenRequestDidFailed() async throws {
+            // given
+            let windowScene = WindowSceneFactory.makeWindowScene()
+
+            // when
+            let status = try await sut.beginRefundRequest(
+                transactionID: .transactionID,
+                windowScene: windowScene
+            )
+
+            // then
+            if case let .failure(error) = status {
+                XCTAssertEqual(error as NSError, IAPError.refund(error: .failed) as NSError)
+            } else {
+                XCTFail("state must be `failure`")
+            }
+        }
+    }
+
+    // MARK: - Constants
+
+    private extension UInt64 {
+        static let transactionID: UInt64 = 0
+    }
+
+    private extension String {
+        static let productID: String = "product_id"
+    }
+
+#endif