dart-sass/test/utils.dart

// Copyright 2018 Google Inc. Use of this source code is governed by an
// MIT-style license that can be found in the LICENSE file or at
// https://opensource.org/licenses/MIT.

import 'dart:async';
import 'dart:convert';

import 'package:test/test.dart';

import 'package:sass/src/io.dart';

/// A regular expression for matching the URL in a source map comment.
final _sourceMapCommentRegExp = RegExp(r"/\*# sourceMappingURL=(.*) \*/\s*$");

/// Returns a [Future] that waits long enough for modification times to be
/// different.
///
/// Windows (or at least Appveyor) seems to require a more coarse-grained time
/// than Unixes.
Future<void> get tick =>
    Future.delayed(Duration(milliseconds: isWindows ? 1000 : 50));

/// Loads and decodes the source map embedded as a `data:` URI in [css].
///
/// Throws a [TestFailure] if [css] doesn't have such a source map.
Map<String, Object> embeddedSourceMap(String css) {
  expect(css, matches(_sourceMapCommentRegExp));

  var match = _sourceMapCommentRegExp.firstMatch(css);
  var data = Uri.parse(match[1]).data;
  expect(data.mimeType, equals("application/json"));
  return jsonDecode(data.contentAsString()) as Map<String, Object>;
}