Add mock mixins of Chopper components. (#529)

chopper/lib/src/base.dart

@@ -515,6 +515,17 @@ base class ChopperClient {
   Stream<Response> get onResponse => _responseController.stream;
 }
 
+///
+/// [ChopperClient] mixin for the purposes of creating mocks
+/// using a mocking framework such as Mockito or Mocktail.
+///
+/// ```dart
+/// base class MockChopperClient extends Mock with MockChopperClientMixin {}
+/// ```
+///
+@visibleForTesting
+base mixin MockChopperClientMixin implements ChopperClient {}
+
 /// A marker and helper class used by `chopper_generator` to generate network
 /// call implementations.
 ///

chopper/lib/src/chopper_log_record.dart

@@ -1,5 +1,6 @@
 import 'package:chopper/src/request.dart';
 import 'package:chopper/src/response.dart';
+import 'package:meta/meta.dart';
 
 final class ChopperLogRecord {
   const ChopperLogRecord(this.message, {this.request, this.response});
@@ -11,3 +12,14 @@ final class ChopperLogRecord {
   @override
   String toString() => message;
 }
+
+///
+/// [ChopperLogRecord] mixin for the purposes of creating mocks
+/// using a mocking framework such as Mockito or Mocktail.
+///
+/// ```dart
+/// base class MockChopperLogRecord extends Mock with MockChopperLogRecordMixin {}
+/// ```
+///
+@visibleForTesting
+base mixin MockChopperLogRecordMixin implements ChopperLogRecord {}

chopper/lib/src/request.dart

@@ -237,6 +237,17 @@ base class Request extends http.BaseRequest with EquatableMixin {
       ];
 }
 
+///
+/// [Request] mixin for the purposes of creating mocks
+/// using a mocking framework such as Mockito or Mocktail.
+///
+/// ```dart
+/// base class MockRequest extends Mock with MockRequestMixin {}
+/// ```
+///
+@visibleForTesting
+base mixin MockRequestMixin implements Request {}
+
 /// Represents a part in a multipart request.
 @immutable
 final class PartValue<T> with EquatableMixin {
@@ -263,8 +274,30 @@ final class PartValue<T> with EquatableMixin {
       ];
 }
 
+///
+/// [PartValue] mixin for the purposes of creating mocks
+/// using a mocking framework such as Mockito or Mocktail.
+///
+/// ```dart
+/// base class MockPartValue<T> extends Mock with MockPartValueMixin<T> {}
+/// ```
+///
+@visibleForTesting
+base mixin MockPartValueMixin<T> implements PartValue<T> {}
+
 /// Represents a file [PartValue] in a multipart request.
 @immutable
 final class PartValueFile<T> extends PartValue<T> {
   const PartValueFile(super.name, super.value);
 }
+
+///
+/// [PartValueFile] mixin for the purposes of creating mocks
+/// using a mocking framework such as Mockito or Mocktail.
+///
+/// ```dart
+/// base class MockPartValueFile<T> extends Mock with MockPartValueFileMixin<T> {}
+/// ```
+///
+@visibleForTesting
+base mixin MockPartValueFileMixin<T> implements PartValueFile<T> {}

chopper/lib/src/response.dart

@@ -74,3 +74,14 @@ base class Response<BodyType> with EquatableMixin {
         error,
       ];
 }
+
+///
+/// [Response] mixin for the purposes of creating mocks
+/// using a mocking framework such as Mockito or Mocktail.
+///
+/// ```dart
+/// base class MockResponse<BodyType> extends Mock with MockResponseMixin<BodyType> {}
+/// ```
+///
+@visibleForTesting
+base mixin MockResponseMixin<BodyType> implements Response<BodyType> {}