feature/add-callback-and-async-callback

lib/src/adapters/dio_adapter.dart

@@ -40,7 +40,7 @@ class DioAdapter with Recording, RequestHandling implements HttpClientAdapter {
     }
 
     await setDefaultRequestHeaders(dio, requestOptions);
-    final response = mockResponse(requestOptions);
+    final response = await mockResponse(requestOptions);
 
     // Waits for defined duration.
     if (response.delay != null) await Future.delayed(response.delay!);

lib/src/handlers/request_handler.dart

@@ -20,6 +20,28 @@ abstract class MockServer {
     Duration? delay,
   });
 
+  void replyCallback(
+    int statusCode,
+    MockDataCallback data, {
+    Map<String, List<String>> headers = const {
+      Headers.contentTypeHeader: [Headers.jsonContentType],
+    },
+    String? statusMessage,
+    bool isRedirect = false,
+    Duration? delay,
+  });
+
+  void replyCallbackAsync(
+    int statusCode,
+    MockDataCallbackAsync data, {
+    Map<String, List<String>> headers = const {
+      Headers.contentTypeHeader: [Headers.jsonContentType],
+    },
+    String? statusMessage,
+    bool isRedirect = false,
+    Duration? delay,
+  });
+
   void throws(
     int statusCode,
     DioException dioError, {
@@ -31,7 +53,7 @@ abstract class MockServer {
 /// constructs the configured [MockResponse].
 class RequestHandler implements MockServer {
   /// This is the response.
-  late MockResponse Function(RequestOptions options) mockResponse;
+  late Future<MockResponse> Function(RequestOptions options) mockResponse;
 
   /// Stores [MockResponse] in [mockResponse].
   @override
@@ -50,7 +72,7 @@ class RequestHandler implements MockServer {
         ) ??
         false;
 
-    mockResponse = (requestOptions) {
+    mockResponse = (requestOptions) async {
       if (data is Uint8List) {
         return MockResponseBody.fromBytes(
           data,
@@ -77,9 +99,72 @@ class RequestHandler implements MockServer {
     };
   }
 
+  /// Stores [MockResponse] in [mockResponse].
+  @override
+  void replyCallback(
+    int statusCode,
+    MockDataCallback data, {
+    Map<String, List<String>> headers = const {
+      Headers.contentTypeHeader: [Headers.jsonContentType],
+    },
+    String? statusMessage,
+    bool isRedirect = false,
+    Duration? delay,
+  }) {
+    final isJsonContentType = headers[Headers.contentTypeHeader]?.contains(
+          Headers.jsonContentType,
+        ) ??
+        false;
+
+    mockResponse = (requestOptions) async {
+      final rawData = data(requestOptions);
+
+      return MockResponseBody.from(
+        isJsonContentType ? jsonEncode(rawData) : rawData,
+        statusCode,
+        headers: headers,
+        statusMessage: statusMessage,
+        isRedirect: isRedirect,
+        delay: delay,
+      );
+    };
+  }
+
+  /// Stores [MockResponse] in [mockResponse].
+  @override
+  void replyCallbackAsync(
+    int statusCode,
+    MockDataCallbackAsync data, {
+    Map<String, List<String>> headers = const {
+      Headers.contentTypeHeader: [Headers.jsonContentType],
+    },
+    String? statusMessage,
+    bool isRedirect = false,
+    Duration? delay,
+  }) {
+    final isJsonContentType = headers[Headers.contentTypeHeader]?.contains(
+          Headers.jsonContentType,
+        ) ??
+        false;
+
+    mockResponse = (requestOptions) async {
+      final rawData = await data(requestOptions);
+
+      return MockResponseBody.from(
+        isJsonContentType ? jsonEncode(rawData) : rawData,
+        statusCode,
+        headers: headers,
+        statusMessage: statusMessage,
+        isRedirect: isRedirect,
+        delay: delay,
+      );
+    };
+  }
+
   /// Stores the [DioException] inside the [mockResponse].
   @override
   void throws(int statusCode, DioException dioError, {Duration? delay}) {
-    mockResponse = (requestOptions) => MockDioException.from(dioError, delay);
+    mockResponse =
+        (requestOptions) async => MockDioException.from(dioError, delay);
   }
 }

lib/src/interceptors/dio_interceptor.dart

@@ -24,7 +24,7 @@ class DioInterceptor extends Interceptor with Recording, RequestHandling {
   @override
   void onRequest(requestOptions, requestInterceptorHandler) async {
     await setDefaultRequestHeaders(dio, requestOptions);
-    final response = mockResponse(requestOptions);
+    final response = await mockResponse(requestOptions);
 
     // Reject the response if type is MockDioException.
     if (isMockDioException(response)) {

lib/src/types.dart

@@ -9,9 +9,13 @@ typedef MockServerCallback = void Function(MockServer server);
 
 /// Type for [Recording]'s [ResponseBody], which takes [RequestOptions] as a parameter
 /// and compares its signature to saved [Request]'s signature and chooses right response.
-typedef MockResponseBodyCallback = MockResponse Function(
+typedef MockResponseBodyCallback = Future<MockResponse> Function(
   RequestOptions options,
 );
 
 /// Type for expect data as function
 typedef MockDataCallback = dynamic Function(RequestOptions options);
+
+/// Type for async expect data as function
+typedef MockDataCallbackAsync = Future<dynamic> Function(
+    RequestOptions options);