public void TestSqr()
{
// Arrage
var calc = new Calculator();
// Act
var sqr = calc.Sqr("2");
var sqr1 = calc.Sqr("0");
var sqr2 = calc.Sqr("-5");
// Assert
Assert.AreEqual(4, sqr);
Assert.AreEqual(0, sqr1);
Assert.AreEqual(25, sqr2);
}