Flutter Fake HttpClient

main.dart

import 'dart:async';
import 'dart:convert';
import 'dart:io';
import 'package:flutter/material.dart';

void main() => HttpOverrides.runWithHttpOverrides(
      () => runApp(
        const MainApp(),
      ),
      FakeHttpOverrides(),
    );

class _MainAppState extends State<MainApp> {
  var text = 'Loading...';

  Future<void> loadData() async {
    final request = await HttpClient().getUrl(Uri.parse('https://google.com'));
    final response = await request.close();
    final body = await response.transform(utf8.decoder).join();
    setState(() {
      text = body;
    });
  }

  @override
  Widget build(BuildContext context) => MaterialApp(
        home: Scaffold(
          body: Center(
            child: Text(text),
          ),
        ),
      );

  @override
  void initState() {
    super.initState();
    unawaited(loadData());
  }
}

class MainApp extends StatefulWidget {
  const MainApp({super.key});

  @override
  State<MainApp> createState() => _MainAppState();
}

class FakeClient implements HttpClient {
  @override
  bool autoUncompress = true;

  @override
  Duration? connectionTimeout;

  @override
  Duration idleTimeout = const Duration(seconds: 15);

  @override
  int? maxConnectionsPerHost;

  @override
  String? userAgent;

  @override
  void addCredentials(
      Uri url, String realm, HttpClientCredentials credentials) {
    // TODO: implement addCredentials
  }

  @override
  void addProxyCredentials(
      String host, int port, String realm, HttpClientCredentials credentials) {
    // TODO: implement addProxyCredentials
  }

  @override
  set authenticate(
      Future<bool> Function(Uri url, String scheme, String? realm)? f) {
    // TODO: implement authenticate
  }

  @override
  set authenticateProxy(
      Future<bool> Function(
              String host, int port, String scheme, String? realm)?
          f) {
    // TODO: implement authenticateProxy
  }

  @override
  set badCertificateCallback(
      bool Function(X509Certificate cert, String host, int port)? callback) {
    // TODO: implement badCertificateCallback
  }

  @override
  void close({bool force = false}) {
    // TODO: implement close
  }

  @override
  set connectionFactory(
      Future<ConnectionTask<Socket>> Function(
              Uri url, String? proxyHost, int? proxyPort)?
          f) {
    // TODO: implement connectionFactory
  }

  @override
  Future<HttpClientRequest> delete(String host, int port, String path) {
    // TODO: implement delete
    throw UnimplementedError();
  }

  @override
  Future<HttpClientRequest> deleteUrl(Uri url) {
    // TODO: implement deleteUrl
    throw UnimplementedError();
  }

  @override
  set findProxy(String Function(Uri url)? f) {
    // TODO: implement findProxy
  }

  @override
  Future<HttpClientRequest> get(String host, int port, String path) {
    // TODO: implement get
    throw UnimplementedError();
  }

  @override
  Future<HttpClientRequest> getUrl(Uri url) async {
    return MockHttpClientRequest();
  }

  @override
  Future<HttpClientRequest> head(String host, int port, String path) {
    // TODO: implement head
    throw UnimplementedError();
  }

  @override
  Future<HttpClientRequest> headUrl(Uri url) {
    // TODO: implement headUrl
    throw UnimplementedError();
  }

  @override
  set keyLog(Function(String line)? callback) {
    // TODO: implement keyLog
  }

  @override
  Future<HttpClientRequest> open(
      String method, String host, int port, String path) {
    // TODO: implement open
    throw UnimplementedError();
  }

  @override
  Future<HttpClientRequest> openUrl(String method, Uri url) {
    // TODO: implement openUrl
    throw UnimplementedError();
  }

  @override
  Future<HttpClientRequest> patch(String host, int port, String path) {
    // TODO: implement patch
    throw UnimplementedError();
  }

  @override
  Future<HttpClientRequest> patchUrl(Uri url) {
    // TODO: implement patchUrl
    throw UnimplementedError();
  }

  @override
  Future<HttpClientRequest> post(String host, int port, String path) {
    // TODO: implement post
    throw UnimplementedError();
  }

  @override
  Future<HttpClientRequest> postUrl(Uri url) {
    // TODO: implement postUrl
    throw UnimplementedError();
  }

  @override
  Future<HttpClientRequest> put(String host, int port, String path) {
    // TODO: implement put
    throw UnimplementedError();
  }

  @override
  Future<HttpClientRequest> putUrl(Uri url) {
    // TODO: implement putUrl
    throw UnimplementedError();
  }
}

class FakeHttpOverrides extends HttpOverrides {
  @override
  HttpClient createHttpClient(SecurityContext? context) => FakeClient();
}

class MockHttpClientRequest implements HttpClientRequest {
  @override
  Future<HttpClientResponse> close() {
    return Future.value(MockHttpClientResponse());
  }

  @override
  bool bufferOutput = true;

  @override
  int contentLength = 5;

  @override
  Encoding encoding = utf8;

  @override
  bool followRedirects = true;

  @override
  int maxRedirects = 5;

  @override
  bool persistentConnection = true;

  @override
  void abort([Object? exception, StackTrace? stackTrace]) {
    // TODO: implement abort
  }

  @override
  void add(List<int> data) {
    // TODO: implement add
  }

  @override
  void addError(Object error, [StackTrace? stackTrace]) {
    // TODO: implement addError
  }

  @override
  Future addStream(Stream<List<int>> stream) {
    // TODO: implement addStream
    throw UnimplementedError();
  }

  @override
  // TODO: implement connectionInfo
  HttpConnectionInfo? get connectionInfo => throw UnimplementedError();

  @override
  // TODO: implement cookies
  List<Cookie> get cookies => throw UnimplementedError();

  @override
  // TODO: implement done
  Future<HttpClientResponse> get done => throw UnimplementedError();

  @override
  Future flush() {
    // TODO: implement flush
    throw UnimplementedError();
  }

  @override
  // TODO: implement headers
  HttpHeaders get headers => throw UnimplementedError();

  @override
  // TODO: implement method
  String get method => throw UnimplementedError();

  @override
  // TODO: implement uri
  Uri get uri => throw UnimplementedError();

  @override
  void write(Object? object) {
    // TODO: implement write
  }

  @override
  void writeAll(Iterable objects, [String separator = ""]) {
    // TODO: implement writeAll
  }

  @override
  void writeCharCode(int charCode) {
    // TODO: implement writeCharCode
  }

  @override
  void writeln([Object? object = ""]) {
    // TODO: implement writeln
  }
}

class FakeHttpHeaders implements HttpHeaders {
  @override
  bool chunkedTransferEncoding = false;

  @override
  int contentLength = 5;

  @override
  ContentType? contentType;

  @override
  DateTime? date;

  @override
  DateTime? expires;

  @override
  String? host;

  @override
  DateTime? ifModifiedSince;

  @override
  bool persistentConnection = false;

  @override
  int? port;

  @override
  List<String>? operator [](String name) {
    // TODO: implement []
    throw UnimplementedError();
  }

  @override
  void add(String name, Object value, {bool preserveHeaderCase = false}) {
    // TODO: implement add
  }

  @override
  void clear() {
    // TODO: implement clear
  }

  @override
  void forEach(void Function(String name, List<String> values) action) {
    // TODO: implement forEach
  }

  @override
  void noFolding(String name) {
    // TODO: implement noFolding
  }

  @override
  void remove(String name, Object value) {
    // TODO: implement remove
  }

  @override
  void removeAll(String name) {
    // TODO: implement removeAll
  }

  @override
  void set(String name, Object value, {bool preserveHeaderCase = false}) {
    // TODO: implement set
  }

  @override
  String? value(String name) {
    // TODO: implement value
    throw UnimplementedError();
  }
}

class MockHttpClientResponse extends Stream<List<int>>
    implements HttpClientResponse {
  @override
  int get statusCode => HttpStatus.ok;

  @override
  HttpHeaders get headers => FakeHttpHeaders();

  Stream<List<int>> get content => Stream.fromIterable(
      [utf8.encode('You are seeing data from the fake HttpClient')]);

  // The HttpClientResponse is also a stream, so we have to implement the "listen" method
  @override
  StreamSubscription<List<int>> listen(
    void Function(List<int> event)? onData, {
    Function? onError,
    void Function()? onDone,
    bool? cancelOnError,
  }) {
    return content.listen(onData,
        onError: onError, onDone: onDone, cancelOnError: cancelOnError);
  }

  @override
  // TODO: implement certificate
  X509Certificate? get certificate => throw UnimplementedError();

  @override
  // TODO: implement compressionState
  HttpClientResponseCompressionState get compressionState =>
      throw UnimplementedError();

  @override
  // TODO: implement connectionInfo
  HttpConnectionInfo? get connectionInfo => throw UnimplementedError();

  @override
  // TODO: implement contentLength
  int get contentLength => throw UnimplementedError();

  @override
  // TODO: implement cookies
  List<Cookie> get cookies => throw UnimplementedError();

  @override
  Future<Socket> detachSocket() {
    // TODO: implement detachSocket
    throw UnimplementedError();
  }

  @override
  // TODO: implement isRedirect
  bool get isRedirect => throw UnimplementedError();

  @override
  // TODO: implement persistentConnection
  bool get persistentConnection => throw UnimplementedError();

  @override
  // TODO: implement reasonPhrase
  String get reasonPhrase => throw UnimplementedError();

  @override
  Future<HttpClientResponse> redirect(
      [String? method, Uri? url, bool? followLoops]) {
    // TODO: implement redirect
    throw UnimplementedError();
  }

  @override
  // TODO: implement redirects
  List<RedirectInfo> get redirects => throw UnimplementedError();

  // Override other necessary methods with empty implementations...
}