public void Enqueue_WhenAnItemIsDequeued_EnqueingShouldAddItAtStart()
{
// Arrange
var q = new Queue<int>();
q.Enqueue(10);
q.Enqueue(20);
q.Enqueue(30);
q.Dequeue();
// Act
q.Enqueue(40);
// Assert
Assert.AreEqual(3, q.Count, "3 items should be in the queue.");
Assert.AreEqual(1, q.GetHeadAndTail().Item1, "Head node should be pointing to the second slot.");
Assert.AreEqual(3, q.GetHeadAndTail().Item2, "Tail should be pointing to the index 3.");
Assert.AreEqual(0, q.GetBackingStore()[0], "Should contain new value.");
Assert.AreEqual(20, q.GetBackingStore()[1], "Should contain the 20 at index 1.");
Assert.AreEqual(30, q.GetBackingStore()[2], "Should contain 30 at index 2.");
Assert.AreEqual(40, q.GetBackingStore()[3], "Should contain 30 at index 2.");
}
public void Dequeue_ShouldReturnFirstInItem_AndUpdateHeadIndex()
{
// Arrange
var q = new Queue<int>();
q.Enqueue(10);
q.Enqueue(20);
// Act
var result = q.Dequeue();
// Assert
Assert.AreEqual(10, result, "Should return the first element.");
Assert.AreEqual(1, q.GetHeadAndTail().Item1, "Head element index should update");
Assert.AreEqual(1, q.GetHeadAndTail().Item2, "Tail element index should not change.");
Assert.AreEqual(0, q.GetBackingStore()[0], "Old head element should be empty (zero)");
Assert.AreEqual(1, q.Count, "Queue length should be 1.");
}
public void Enqueue_WhenNumberOfElementsBecomeMoreThan4_BackingStoreShouldIncreaseInSize()
{
// Arrange
var q = new Queue<int>();
q.Enqueue(1);
q.Enqueue(2);
q.Enqueue(3);
q.Enqueue(4);
// Act
q.Enqueue(5);
// Assert
Assert.AreEqual(5, q.Count, "Length shall be 5");
Assert.AreEqual(8, q.GetBackingStore().Length, "Backing store should have doubled the size.");
Assert.AreEqual(1, q.GetBackingStore()[0], "1 should be at position 0");
Assert.AreEqual(2, q.GetBackingStore()[1], "2 should be at position 1");
Assert.AreEqual(3, q.GetBackingStore()[2], "3 should be at position 2");
Assert.AreEqual(4, q.GetBackingStore()[3], "4 should be at position 3");
Assert.AreEqual(5, q.GetBackingStore()[4], "5 should be at position 4");
Assert.AreEqual(0, q.GetHeadAndTail().Item1, "Head should still be 0.");
Assert.AreEqual(4, q.GetHeadAndTail().Item2, "Tail should be at 4.");
}
public void Peek_ShouldReturnTheHeadItem_ShouldNotRemoveFromQueue()
{
// Arrange
var q = new Queue<int>();
q.Enqueue(20);
q.Enqueue(30);
q.Dequeue();
// Act
var result = q.Peek();
// Assert
Assert.AreEqual(30, result, "Should return expected value 30.");
Assert.AreEqual(0, q.GetBackingStore()[0], "Index 0 should be empty.");
Assert.AreEqual(30, q.GetBackingStore()[1], "Index 1 should have 30.");
}
public void Enqueue_WhenThereAreNoItems_NewItemShouldBeTheFirst()
{
// Arrange
var q = new Queue<int>();
// Act
q.Enqueue(10);
// Assert
Assert.AreEqual(1, q.Count, "Should only be a single item in the queue.");
Assert.AreEqual(10, q.GetBackingStore()[0], "First element should be the given value.");
Assert.AreEqual(0, q.GetHeadAndTail().Item1, "Head node should be 0.");
Assert.AreEqual(0, q.GetHeadAndTail().Item2, "Tail node should be 0.");
}
public void Enqueue_WhenSecondItemAdded_SecondItemShouldBeTheTail()
{
// Arrange
var q = new Queue<int>();
q.Enqueue(10);
// Act
q.Enqueue(20);
// Assert
Assert.AreEqual(2, q.Count, "Number of items in the queue.");
Assert.AreEqual(10, q.GetBackingStore()[0], "Frist element should be 10.");
Assert.AreEqual(20, q.GetBackingStore()[1], "Second element should be 20.");
Assert.AreEqual(0, q.GetHeadAndTail().Item1, "Position of head should not change.");
Assert.AreEqual(1, q.GetHeadAndTail().Item2, "Position of tail should be the new element.");
}