public void ToArrayCopiesItemsInCollectionToANewArray() { // arrange var itemDummy = PriorityItemHelper.CreatePriorityMock(1); var higherPriorityDummy = PriorityItemHelper.CreatePriorityMock(0); var sut = new PriorityCollection <IPriorityItem>(); sut.TryAdd(itemDummy.Object); sut.TryAdd(higherPriorityDummy.Object); // act var array = sut.ToArray(); // assert array.Length.Should().Be(2); array.First().Should().Be(higherPriorityDummy.Object); }