Add transformed operation to Future

StripeCore/StripeCore.xcodeproj/project.pbxproj

@@ -37,6 +37,7 @@
 		45DAE581F74EF7E11C64212B /* InstallMethod.swift in Sources */ = {isa = PBXBuildFile; fileRef = 21E64986F72C7BD8B1105A95 /* InstallMethod.swift */; };
 		48A6CCB4008A5060C2655C5F /* XCTestCase+Stripe.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2DE48D0086BED21F9E837D0B /* XCTestCase+Stripe.swift */; };
 		4910B9282C3D8F3F00B030D4 /* Result+Extensions.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4910B9272C3D8F3F00B030D4 /* Result+Extensions.swift */; };
+		49ECDA412CA340E100F647F0 /* AsyncTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 49ECDA402CA340E100F647F0 /* AsyncTests.swift */; };
 		4B2FAC57E03D8654A177C408 /* Dictionary+Stripe.swift in Sources */ = {isa = PBXBuildFile; fileRef = 7727AEEFD2FC880BADDA1872 /* Dictionary+Stripe.swift */; };
 		53D46A03B77577EE21F4B166 /* StripeCodableTest.swift in Sources */ = {isa = PBXBuildFile; fileRef = 1FCE36551600C3E53BEAF8F0 /* StripeCodableTest.swift */; };
 		552DA7969984C443617DBC3E /* STPMultipartFormDataPart.swift in Sources */ = {isa = PBXBuildFile; fileRef = E1C72BA9C44FF60A0E7BEF76 /* STPMultipartFormDataPart.swift */; };
@@ -228,6 +229,7 @@
 		4910B9272C3D8F3F00B030D4 /* Result+Extensions.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "Result+Extensions.swift"; sourceTree = "<group>"; };
 		49424775D3233411D9C2473B /* StripeCodable.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = StripeCodable.swift; sourceTree = "<group>"; };
 		49538DBF8457D96707A2DA56 /* nl */ = {isa = PBXFileReference; lastKnownFileType = text.plist.strings; name = nl; path = nl.lproj/Localizable.strings; sourceTree = "<group>"; };
+		49ECDA402CA340E100F647F0 /* AsyncTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AsyncTests.swift; sourceTree = "<group>"; };
 		4A8030BF88608CA86E295F18 /* Enums+CustomStringConvertible.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "Enums+CustomStringConvertible.swift"; sourceTree = "<group>"; };
 		4C51E3FA5EE3587BB7BBC634 /* STPError.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = STPError.swift; sourceTree = "<group>"; };
 		4EC3BCEEECB3E1485B18F0C4 /* FinancialConnectionsSDKInterface.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = FinancialConnectionsSDKInterface.swift; sourceTree = "<group>"; };
@@ -413,6 +415,7 @@
 			isa = PBXGroup;
 			children = (
 				7F2E1D80D0342CF09CB05415 /* URLEncoderTest.swift */,
+				49ECDA402CA340E100F647F0 /* AsyncTests.swift */,
 			);
 			path = Helpers;
 			sourceTree = "<group>";
@@ -941,6 +944,7 @@
 				84487D8E9B08106C89753536 /* Error_SerializeForLoggingTest.swift in Sources */,
 				0A78AD04075C43A4059C344E /* STPAnalyticsClientTest.swift in Sources */,
 				934CCB00769674F13192A126 /* Dictionary+StripeTests.swift in Sources */,
+				49ECDA412CA340E100F647F0 /* AsyncTests.swift in Sources */,
 				A50CB2ACAC1DCF9539D76F25 /* NSArray+StripeCoreTest.swift in Sources */,
 				F5DB5D52E2668136FF6D70D6 /* NSMutableURLRequest+StripeTest.swift in Sources */,
 				8AD68C8D00A0BCF94E5230DC /* UIImage+StripeCoreTests.swift in Sources */,

StripeCore/StripeCore/Source/Helpers/Async.swift

@@ -112,6 +112,14 @@ import Foundation
 
         return promise
     }
+
+    public func transformed<T>(
+        with closure: @escaping (Value) throws -> T
+    ) -> Future<T> {
+         chained { value in
+             try Promise(value: closure(value))
+        }
+    }
 }
 
 @_spi(STP) public class Promise<Value>: Future<Value> {

StripeCore/StripeCoreTests/Helpers/AsyncTests.swift

@@ -0,0 +1,155 @@
+//
+//  AsyncTests.swift
+//  StripeCoreTests
+//
+//  Created by Mat Schmid on 2024-09-24.
+//
+
+@_spi(STP) @testable import StripeCore
+import XCTest
+
+class AsyncTests: XCTestCase {
+
+    func testFutureObserveWithImmediateResult() {
+        let promise = Promise<Int>(value: 42)
+        let expectation = XCTestExpectation(description: "Observe immediate result")
+
+        promise.observe { result in
+            XCTAssertEqual(result.successValue, 42)
+            expectation.fulfill()
+        }
+
+        wait(for: [expectation], timeout: 1.0)
+    }
+
+    func testFutureObserveWithDelayedResult() {
+        let promise = Promise<Int>()
+        let expectation = XCTestExpectation(description: "Observe delayed result")
+
+        promise.observe { result in
+            XCTAssertEqual(result.successValue, 42)
+            expectation.fulfill()
+        }
+
+        promise.resolve(with: 42)
+        wait(for: [expectation], timeout: 1.0)
+    }
+
+    func testFutureChainedSuccess() {
+        let promise = Promise<Int>(value: 42)
+        let chainedFuture = promise.chained { value in
+            return Promise(value: value * 2)
+        }
+
+        let expectation = XCTestExpectation(description: "Chained success")
+
+        chainedFuture.observe { result in
+            XCTAssertEqual(result.successValue, 84)
+            expectation.fulfill()
+        }
+
+        wait(for: [expectation], timeout: 1.0)
+    }
+
+    func testFutureChainedFailure() {
+        let promise = Promise<Int>()
+        let chainedFuture: Future<Int> = promise.chained { _ in
+            return Promise(error: NSError(domain: "test", code: 0, userInfo: nil))
+        }
+
+        let expectation = XCTestExpectation(description: "Chained failure")
+
+        chainedFuture.observe { result in
+            XCTAssertNotNil(result.failureValue)
+            expectation.fulfill()
+        }
+
+        promise.reject(with: NSError(domain: "test", code: 0, userInfo: nil))
+        wait(for: [expectation], timeout: 1.0)
+    }
+
+    func testFutureTransformed() {
+        let promise = Promise<Int>(value: 42)
+        let transformedFuture = promise.transformed { value in
+            return value * 2
+        }
+
+        let expectation = XCTestExpectation(description: "Transformed success")
+
+        transformedFuture.observe { result in
+            XCTAssertEqual(result.successValue, 84)
+            expectation.fulfill()
+        }
+
+        wait(for: [expectation], timeout: 1.0)
+    }
+
+    func testFutureTransformedFailure() {
+        let promise = Promise<Int>()
+        let transformedFuture = promise.transformed { value in
+            return value * 2
+        }
+
+        let expectation = XCTestExpectation(description: "Transformed failure")
+
+        transformedFuture.observe { result in
+            XCTAssertNotNil(result.failureValue)
+            expectation.fulfill()
+        }
+
+        promise.reject(with: NSError(domain: "test", code: 0, userInfo: nil))
+        wait(for: [expectation], timeout: 1.0)
+    }
+
+    func testPromiseResolved() {
+        let promise = Promise<Int>()
+        let expectation = XCTestExpectation(description: "Promise resolved")
+
+        promise.observe { result in
+            XCTAssertEqual(result.successValue, 42)
+            expectation.fulfill()
+        }
+
+        promise.resolve(with: 42)
+        wait(for: [expectation], timeout: 1.0)
+    }
+
+    func testPromiseRejected() {
+        let promise = Promise<Int>()
+        let expectation = XCTestExpectation(description: "Promise rejected")
+
+        promise.observe { result in
+            XCTAssertNotNil(result.failureValue)
+            expectation.fulfill()
+        }
+
+        promise.reject(with: NSError(domain: "test", code: 0, userInfo: nil))
+        wait(for: [expectation], timeout: 1.0)
+    }
+
+    func testPromiseFullfill() {
+        let promise = Promise<Int>()
+        let expectation = XCTestExpectation(description: "Promise fullfill")
+
+        promise.observe { result in
+            XCTAssertEqual(result.successValue, 42)
+            expectation.fulfill()
+        }
+
+        promise.fullfill(with: .success(42))
+        wait(for: [expectation], timeout: 1.0)
+    }
+}
+
+private extension Result {
+    var successValue: Success? {
+        try? get()
+    }
+
+    var failureValue: Error? {
+        guard case .failure(let error) = self else {
+            return nil
+        }
+        return error
+    }
+}