test/builder/contains_ignoring_formatting.dart

// Copyright 2024 Dart Mockito authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

import 'package:test/test.dart';

/// Returns a [Matcher] that checks that the actual string of Dart code
/// contains [expected] when ignoring differences due to formatting: whitespace
/// and trailing commas.
Matcher containsIgnoringFormatting(String expected) =>
    _ContainsIgnoringFormattingMatcher(expected);

/// Matches a string that contains a given string, ignoring differences related
/// to formatting: whitespace and trailing commas.
class _ContainsIgnoringFormattingMatcher extends Matcher {
  /// Matches one or more whitespace characters, or a trailing comma.
  ///
  /// A trailing comma is one followed by a closing bracket of some kind.
  static final _whitespaceOrTrailingCommaPattern = RegExp(
    r'\s+|,\s*(?=[)}\]])',
  );

  /// The string that the actual value must contain in order for the match to
  /// succeed.
  final String _expected;

  _ContainsIgnoringFormattingMatcher(this._expected);

  @override
  Description describe(Description description) {
    return description.add(
      'Contains "$_expected" when ignoring source formatting',
    );
  }

  @override
  bool matches(item, Map matchState) =>
      _stripFormatting(item.toString()).contains(_stripFormatting(_expected));

  /// Removes whitespace and trailing commas.
  ///
  /// Note that the result is not valid code because it means adjacent
  /// identifiers and operators may be joined in ways that break the semantics.
  /// The goal is not to produce an but valid version of the code, just to
  /// produce a string that will reliably match the actual string when it has
  /// also been stripped the same way.
  String _stripFormatting(String code) =>
      code.replaceAll(_whitespaceOrTrailingCommaPattern, '');
}