POC response handler for dynamic requests

Sources/Mocker/Mock.swift

@@ -101,6 +101,9 @@ public struct Mock: Equatable {
     /// The on request handler which will be executed everytime this `Mock` was started. Can be used within unit tests for validating that a request has been started. The handler must be set before calling `register`.
     public var onRequestHandler: OnRequestHandler?
 
+    /// Optional response handler which could be used to dynamically generate the response
+    public var responseHandler: ResponseHandler?
+
     /// Can only be set internally as it's used by the `expectationForRequestingMock(_:)` method.
     var onRequestExpectation: XCTestExpectation?
 
@@ -290,6 +293,30 @@ public struct Mock: Equatable {
         )
     }
 
+    /// Creates a `Mock` for the given `URLRequest`.
+    ///
+    /// - Parameters:
+    ///   - request: The URLRequest, from which the URL and request method is used to match for and to return the mocked data for.
+    ///   - ignoreQuery: If `true`, checking the URL will ignore the query and match only for the scheme, host and path. Defaults to `false`.
+    ///   - cacheStoragePolicy: The caching strategy. Defaults to `notAllowed`.
+    ///   - responseHandler: The response handler to dynamicly generate the response for this Mock
+    public init(request: URLRequest, ignoreQuery: Bool = false, cacheStoragePolicy: URLCache.StoragePolicy = .notAllowed, responseHandler: ResponseHandler) {
+        guard let requestHTTPMethod = Mock.HTTPMethod(rawValue: request.httpMethod ?? "") else {
+            preconditionFailure("Unexpected http method")
+        }
+
+        self.init(
+            url: request.url,
+            ignoreQuery: ignoreQuery,
+            cacheStoragePolicy: cacheStoragePolicy,
+            statusCode: 999, // unused, see responseHandler
+            data: [requestHTTPMethod: "responseHandler should have been used instead of this".data(using: .utf8)!],
+            fileExtensions: nil
+        )
+
+        self.responseHandler = responseHandler
+    }
+
     /// Registers the mock with the shared `Mocker`.
     public func register() {
         Mocker.register(self)

Sources/Mocker/MockingURLProtocol.swift

@@ -36,16 +36,29 @@ open class MockingURLProtocol: URLProtocol {
 
     /// Returns Mocked data based on the mocks register in the `Mocker`. Will end up in an error when no Mock data is found for the request.
     override public func startLoading() {
-        guard
-            let mock = Mocker.mock(for: request),
-            let response = HTTPURLResponse(url: mock.request.url!, statusCode: mock.statusCode, httpVersion: Mocker.httpVersion.rawValue, headerFields: mock.headers),
-            let data = mock.data(for: request)
-        else {
+        guard let mock = Mocker.mock(for: request) else {
             print("\n\n 🚨 No mocked data found for url \(String(describing: request.url?.absoluteString)) method \(String(describing: request.httpMethod)). Did you forget to use `register()`? 🚨 \n\n")
             client?.urlProtocol(self, didFailWithError: Error.missingMockedData(url: String(describing: request.url?.absoluteString)))
             return
         }
 
+        let response: HTTPURLResponse
+        let data: Data
+        if let responseHandler = mock.responseHandler {
+            (response, data) = responseHandler.handleRequest(request)
+        } else if let httpResponse = HTTPURLResponse(
+            url: mock.request.url!,
+            statusCode: mock.statusCode,
+            httpVersion: Mocker.httpVersion.rawValue,
+            headerFields: mock.headers
+        ), let mockData = mock.data(for: request) {
+            response = httpResponse
+            data = mockData
+        } else {
+            print("\n\n 🚨 Unable to create HTTPURLResponse for mock for url \(String(describing: request.url?.absoluteString)) method \(String(describing: request.httpMethod)). 🚨 \n\n")
+            return
+        }
+
         if let onRequestHandler = mock.onRequestHandler {
             onRequestHandler.handleRequest(request)
         }

Sources/Mocker/OnRequestHandler.swift

@@ -113,7 +113,7 @@ public struct OnRequestHandler {
     }
 }
 
-private extension URLRequest {
+extension URLRequest {
     /// We need to use the http body stream data as the URLRequest once launched converts the `httpBody` to this stream of data.
     func httpBodyStreamData() -> Data? {
         guard let bodyStream = self.httpBodyStream else { return nil }
@@ -136,3 +136,4 @@ private extension URLRequest {
         return data
     }
 }
+

Sources/Mocker/ResponseHandler.swift

@@ -0,0 +1,90 @@
+//
+//  RequestResponseHandler.swift
+//
+//
+//  Created by Tieme on 03/10/2024.
+//  Copyright © 2022 WeTransfer. All rights reserved.
+
+import Foundation
+#if canImport(FoundationNetworking)
+import FoundationNetworking
+#endif
+
+/// A handler for a dynamic response
+public struct ResponseHandler {
+
+    public typealias OnRequest<HTTPBody> = (_ request: URLRequest, _ httpBody: HTTPBody?) -> (HTTPURLResponse, Data)
+
+    private let internalCallback: (_ request: URLRequest) -> (HTTPURLResponse, Data)
+
+    /// Creates a new request handler using the given `HTTPBody` type, which can be any `Decodable`.
+    /// - Parameters:
+    ///   - httpBodyType: The decodable type to use for parsing the request body.
+    ///   - callback: The callback which will be called just before the request executes.
+    public init<HTTPBody: Decodable>(httpBodyType: HTTPBody.Type?, callback: @escaping OnRequest<HTTPBody>) {
+        self.init(httpBodyType: httpBodyType, jsonDecoder: JSONDecoder(), callback: callback)
+    }
+
+    /// Creates a new request handler using the given `HTTPBody` type, which can be any `Decodable` and decoding it using the provided `JSONDecoder`.
+    /// - Parameters:
+    ///   - httpBodyType: The decodable type to use for parsing the request body.
+    ///   - jsonDecoder: The decoder to use for decoding the request body.
+    ///   - callback: The callback which will be called just before the request executes.
+    public init<HTTPBody: Decodable>(httpBodyType: HTTPBody.Type?, jsonDecoder: JSONDecoder, callback: @escaping OnRequest<HTTPBody>) {
+        self.internalCallback = { request in
+            guard
+                let httpBody = request.httpBodyStreamData() ?? request.httpBody,
+                let decodedObject = try? jsonDecoder.decode(HTTPBody.self, from: httpBody)
+            else {
+                return callback(request, nil)
+            }
+            return callback(request, decodedObject)
+        }
+    }
+
+    /// Creates a new request handler using the given callback to call on request without parsing the body arguments.
+    /// - Parameter requestCallback: The callback which will be executed just before the request executes, containing the request.
+    public init(requestCallback: @escaping (_ request: URLRequest) -> (HTTPURLResponse, Data)) {
+        self.internalCallback = requestCallback
+    }
+
+    /// Creates a new request handler using the given callback to call on request without parsing the body arguments and without passing the request.
+    /// - Parameter callback: The callback which will be executed just before the request executes.
+    public init(callback: @escaping () -> (HTTPURLResponse, Data)) {
+        self.internalCallback = { _ in
+            callback()
+        }
+    }
+
+    /// Creates a new request handler using the given callback to call on request.
+    /// - Parameter jsonDictionaryCallback: The callback that executes just before the request executes, containing the HTTP Body Arguments as a JSON Object Dictionary.
+    public init(jsonDictionaryCallback: @escaping ((_ request: URLRequest, _ httpBodyArguments: [String: Any]?) -> (HTTPURLResponse, Data))) {
+        self.internalCallback = { request in
+            guard
+                let httpBody = request.httpBodyStreamData() ?? request.httpBody,
+                let jsonObject = try? JSONSerialization.jsonObject(with: httpBody, options: .fragmentsAllowed) as? [String: Any]
+            else {
+                return jsonDictionaryCallback(request, nil)
+            }
+            return jsonDictionaryCallback(request, jsonObject)
+        }
+    }
+
+    /// Creates a new request handler using the given callback to call on request.
+    /// - Parameter jsonDictionaryCallback: The callback that executes just before the request executes, containing the HTTP Body Arguments as a JSON Object Array.
+    public init(jsonArrayCallback: @escaping ((_ request: URLRequest, _ httpBodyArguments: [[String: Any]]?) -> (HTTPURLResponse, Data))) {
+        self.internalCallback = { request in
+            guard
+                let httpBody = request.httpBodyStreamData() ?? request.httpBody,
+                let jsonObject = try? JSONSerialization.jsonObject(with: httpBody, options: .fragmentsAllowed) as? [[String: Any]]
+            else {
+                return jsonArrayCallback(request, nil)
+            }
+            return jsonArrayCallback(request, jsonObject)
+        }
+    }
+
+    func handleRequest(_ request: URLRequest) -> (HTTPURLResponse, Data) {
+        return internalCallback(request)
+    }
+}

Tests/MockerTests/MockerTests.swift

@@ -483,6 +483,38 @@ final class MockerTests: XCTestCase {
         wait(for: [onRequestExpectation], timeout: 2.0)
     }
 
+    func testResponseHandler() {
+        let requestExpectation = self.expectation(description: "Data request should succeed")
+        let responseHandlerExpectation = self.expectation(description: "Data request should start")
+        let originalURL = URL(string: "https://avatars3.githubusercontent.com/u/26250426?v=4&s=400")!
+        var request = URLRequest(url: originalURL)
+
+        let mockedData = MockedData.botAvatarImageFileUrl.data
+        let mock = Mock(request: request, responseHandler: ResponseHandler(callback: {
+            responseHandlerExpectation.fulfill()
+            return (
+                HTTPURLResponse(
+                    url: originalURL,
+                    statusCode: 200,
+                    httpVersion: Mocker.httpVersion.rawValue,
+                    headerFields: nil
+                )!,
+                mockedData
+            )
+        }))
+        mock.register()
+
+        mock.register()
+        URLSession.shared.dataTask(with: originalURL) { (data, _, error) in
+            XCTAssertNil(error)
+            XCTAssertEqual(data, mockedData, "Image should be returned mocked")
+            requestExpectation.fulfill()
+        }.resume()
+
+
+        wait(for: [responseHandlerExpectation, requestExpectation], enforceOrder: true)
+    }
+
     /// It should call the mock after a delay.
     func testDelayedMock() {
         let nonDelayExpectation = expectation(description: "Data request should succeed")