test/queue_list_test.dart

// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

import 'package:collection/collection.dart';
import 'package:test/test.dart';

void main() {
  group('QueueList()', () {
    test('creates an empty QueueList', () {
      expect(QueueList(), isEmpty);
    });

    test('takes an initial capacity', () {
      expect(QueueList(100), isEmpty);
    });
  });

  test('QueueList.from() copies the contents of an iterable', () {
    expect(QueueList.from([1, 2, 3].skip(1)), equals([2, 3]));
  });

  group('add()', () {
    test('adds an element to the end of the queue', () {
      var queue = QueueList.from([1, 2, 3]);
      queue.add(4);
      expect(queue, equals([1, 2, 3, 4]));
    });

    test('expands a full queue', () {
      var queue = atCapacity();
      queue.add(8);
      expect(queue, equals([1, 2, 3, 4, 5, 6, 7, 8]));
    });
  });

  group('addAll()', () {
    test('adds elements to the end of the queue', () {
      var queue = QueueList.from([1, 2, 3]);
      queue.addAll([4, 5, 6]);
      expect(queue, equals([1, 2, 3, 4, 5, 6]));
    });

    test('expands a full queue', () {
      var queue = atCapacity();
      queue.addAll([8, 9]);
      expect(queue, equals([1, 2, 3, 4, 5, 6, 7, 8, 9]));
    });
  });

  group('addFirst()', () {
    test('adds an element to the beginning of the queue', () {
      var queue = QueueList.from([1, 2, 3]);
      queue.addFirst(0);
      expect(queue, equals([0, 1, 2, 3]));
    });

    test('expands a full queue', () {
      var queue = atCapacity();
      queue.addFirst(0);
      expect(queue, equals([0, 1, 2, 3, 4, 5, 6, 7]));
    });
  });

  group('removeFirst()', () {
    test('removes an element from the beginning of the queue', () {
      var queue = QueueList.from([1, 2, 3]);
      expect(queue.removeFirst(), equals(1));
      expect(queue, equals([2, 3]));
    });

    test(
        'removes an element from the beginning of a queue with an internal '
        'gap', () {
      var queue = withInternalGap();
      expect(queue.removeFirst(), equals(1));
      expect(queue, equals([2, 3, 4, 5, 6, 7]));
    });

    test('removes an element from the beginning of a queue at capacity', () {
      var queue = atCapacity();
      expect(queue.removeFirst(), equals(1));
      expect(queue, equals([2, 3, 4, 5, 6, 7]));
    });

    test('throws a StateError for an empty queue', () {
      expect(QueueList().removeFirst, throwsStateError);
    });
  });

  group('removeLast()', () {
    test('removes an element from the end of the queue', () {
      var queue = QueueList.from([1, 2, 3]);
      expect(queue.removeLast(), equals(3));
      expect(queue, equals([1, 2]));
    });

    test('removes an element from the end of a queue with an internal gap', () {
      var queue = withInternalGap();
      expect(queue.removeLast(), equals(7));
      expect(queue, equals([1, 2, 3, 4, 5, 6]));
    });

    test('removes an element from the end of a queue at capacity', () {
      var queue = atCapacity();
      expect(queue.removeLast(), equals(7));
      expect(queue, equals([1, 2, 3, 4, 5, 6]));
    });

    test('throws a StateError for an empty queue', () {
      expect(QueueList().removeLast, throwsStateError);
    });
  });

  group('length', () {
    test('returns the length of a queue', () {
      expect(QueueList.from([1, 2, 3]).length, equals(3));
    });

    test('returns the length of a queue with an internal gap', () {
      expect(withInternalGap().length, equals(7));
    });

    test('returns the length of a queue at capacity', () {
      expect(atCapacity().length, equals(7));
    });
  });

  group('length=', () {
    test('shrinks a larger queue', () {
      var queue = QueueList.from([1, 2, 3]);
      queue.length = 1;
      expect(queue, equals([1]));
    });

    test('grows a smaller queue', () {
      var queue = QueueList<int?>.from([1, 2, 3]);
      queue.length = 5;
      expect(queue, equals([1, 2, 3, null, null]));
    });

    test('throws a RangeError if length is less than 0', () {
      expect(() => QueueList().length = -1, throwsRangeError);
    });

    test('throws an UnsupportedError if element type is non-nullable', () {
      expect(() => QueueList<int>().length = 1, throwsUnsupportedError);
    });
  });

  group('[]', () {
    test('returns individual entries in the queue', () {
      var queue = QueueList.from([1, 2, 3]);
      expect(queue[0], equals(1));
      expect(queue[1], equals(2));
      expect(queue[2], equals(3));
    });

    test('returns individual entries in a queue with an internal gap', () {
      var queue = withInternalGap();
      expect(queue[0], equals(1));
      expect(queue[1], equals(2));
      expect(queue[2], equals(3));
      expect(queue[3], equals(4));
      expect(queue[4], equals(5));
      expect(queue[5], equals(6));
      expect(queue[6], equals(7));
    });

    test('throws a RangeError if the index is less than 0', () {
      var queue = QueueList.from([1, 2, 3]);
      expect(() => queue[-1], throwsRangeError);
    });

    test(
        'throws a RangeError if the index is greater than or equal to the '
        'length', () {
      var queue = QueueList.from([1, 2, 3]);
      expect(() => queue[3], throwsRangeError);
    });
  });

  group('[]=', () {
    test('sets individual entries in the queue', () {
      var queue = QueueList<dynamic>.from([1, 2, 3]);
      queue[0] = 'a';
      queue[1] = 'b';
      queue[2] = 'c';
      expect(queue, equals(['a', 'b', 'c']));
    });

    test('sets individual entries in a queue with an internal gap', () {
      var queue = withInternalGap();
      queue[0] = 'a';
      queue[1] = 'b';
      queue[2] = 'c';
      queue[3] = 'd';
      queue[4] = 'e';
      queue[5] = 'f';
      queue[6] = 'g';
      expect(queue, equals(['a', 'b', 'c', 'd', 'e', 'f', 'g']));
    });

    test('throws a RangeError if the index is less than 0', () {
      var queue = QueueList.from([1, 2, 3]);
      expect(() {
        queue[-1] = 0;
      }, throwsRangeError);
    });

    test(
        'throws a RangeError if the index is greater than or equal to the '
        'length', () {
      var queue = QueueList.from([1, 2, 3]);
      expect(() {
        queue[3] = 4;
      }, throwsRangeError);
    });
  });

  group('throws a modification error for', () {
    var queue;
    setUp(() {
      queue = QueueList.from([1, 2, 3]);
    });

    test('add', () {
      expect(() => queue.forEach((_) => queue.add(4)),
          throwsConcurrentModificationError);
    });

    test('addAll', () {
      expect(() => queue.forEach((_) => queue.addAll([4, 5, 6])),
          throwsConcurrentModificationError);
    });

    test('addFirst', () {
      expect(() => queue.forEach((_) => queue.addFirst(0)),
          throwsConcurrentModificationError);
    });

    test('removeFirst', () {
      expect(() => queue.forEach((_) => queue.removeFirst()),
          throwsConcurrentModificationError);
    });

    test('removeLast', () {
      expect(() => queue.forEach((_) => queue.removeLast()),
          throwsConcurrentModificationError);
    });

    test('length=', () {
      expect(() => queue.forEach((_) => queue.length = 1),
          throwsConcurrentModificationError);
    });
  });

  test('cast does not throw on mutation when the type is valid', () {
    var patternQueue = QueueList<Pattern>()..addAll(['a', 'b']);
    var stringQueue = patternQueue.cast<String>();
    stringQueue.addAll(['c', 'd']);
    expect(stringQueue, const TypeMatcher<QueueList<String>>(),
        reason: 'Expected QueueList<String>, got ${stringQueue.runtimeType}');

    expect(stringQueue, ['a', 'b', 'c', 'd']);

    expect(patternQueue, stringQueue, reason: 'Should forward to original');
  });

  test('cast throws on mutation when the type is not valid', () {
    QueueList<Object> stringQueue = QueueList<String>();
    var numQueue = stringQueue.cast<num>();
    expect(numQueue, const TypeMatcher<QueueList<num>>(),
        reason: 'Expected QueueList<num>, got ${numQueue.runtimeType}');
    expect(
        () => numQueue.add(1),
        // ignore: deprecated_member_use
        throwsA(isA<CastError>()));
  });

  test('cast returns a new QueueList', () {
    var queue = QueueList<String>();
    expect(queue.cast<Pattern>(), isNot(same(queue)));
  });
}

/// Returns a queue whose internal ring buffer is full enough that adding a new
/// element will expand it.
QueueList atCapacity() {
  // Use addAll because `QueueList.from(list)` won't use the default initial
  // capacity of 8.
  return QueueList()..addAll([1, 2, 3, 4, 5, 6, 7]);
}

/// Returns a queue whose internal tail has a lower index than its head.
QueueList withInternalGap() {
  var queue = QueueList.from(<dynamic>[null, null, null, null, 1, 2, 3, 4]);
  for (var i = 0; i < 4; i++) {
    queue.removeFirst();
  }
  for (var i = 5; i < 8; i++) {
    queue.addLast(i);
  }
  return queue;
}

/// Returns a matcher that expects that a closure throws a
/// [ConcurrentModificationError].
final throwsConcurrentModificationError =
    throwsA(TypeMatcher<ConcurrentModificationError>());