flutter_flutter/packages/flutter_test/lib/src/_goldens_web.dart

// Copyright 2014 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

/// @docImport 'matchers.dart';
library;

import 'dart:convert';
import 'dart:js_interop';
import 'dart:typed_data';

import 'package:matcher/expect.dart' show fail;

import 'goldens.dart';
import 'web.dart' as web;

/// An unsupported [GoldenFileComparator] that exists for API compatibility.
class LocalFileComparator extends GoldenFileComparator {
  @override
  Future<bool> compare(Uint8List imageBytes, Uri golden) {
    throw UnsupportedError('LocalFileComparator is not supported on the web.');
  }

  @override
  Future<void> update(Uri golden, Uint8List imageBytes) {
    throw UnsupportedError('LocalFileComparator is not supported on the web.');
  }
}

/// Returns whether [test] and [master] are pixel by pixel identical.
///
/// This method is not supported on the web and throws an [UnsupportedError]
/// when called.
Future<ComparisonResult> compareLists(List<int> test, List<int> master) async {
  throw UnsupportedError('Golden testing is not supported on the web.');
}

/// Implements [GoldenFileComparator] by proxying calls to an HTTP service `/flutter_goldens`.
final class HttpProxyGoldenComparator extends GoldenFileComparator {
  /// Creates a comparator with the given test file being executed.
  ///
  /// Golden file keys will be interpreted as file paths relative to the
  /// directory in which this file resides.
  HttpProxyGoldenComparator(this._testUri);
  final Uri _testUri;

  @override
  Future<bool> compare(Uint8List bytes, Uri golden) async {
    final key = golden.toString();
    final String bytesEncoded = base64.encode(bytes);
    final web.Response response = await web.window
        .fetch(
          'flutter_goldens'.toJS,
          web.RequestInit(
            method: 'POST',
            body: json.encode(<String, Object>{
              'testUri': _testUri.toString(),
              'key': key,
              'bytes': bytesEncoded,
            }).toJS,
          ),
        )
        .toDart;
    final String responseText = (await response.text().toDart).toDart;
    if (responseText == 'true') {
      return true;
    }
    fail(responseText);
  }

  @override
  Future<void> update(Uri golden, Uint8List bytes) async {
    // Update is handled on the server side, just use the same logic here
    await compare(bytes, golden);
  }
}