public void Filter_FilterShouldWork()
{
// Arrange
StackArray <int> sut = new StackArray <int> {
2, 8, 7, 12, 23, 14, 1, 25, 17, 5
};
int[] expected = { 5, 14, 12, 7, 8 };
// Act
IEnumerable <int> actual = sut.Filter(item => item >= 5 && item <= 14);
// Assert
Assert.Equal(expected, actual);
}