@Test
public void testSquareRoot() {
final double DELTA = 1e-15;
a = 0;
double result = calculator.squareRoot(a);
Assert.assertEquals(Math.sqrt(a), result, DELTA);
a = 1;
result = calculator.squareRoot(a);
Assert.assertEquals(Math.sqrt(a), result, DELTA);
a = 25;
result = calculator.squareRoot(a);
Assert.assertEquals(Math.sqrt(a), result, DELTA);
a = 1544646;
result = calculator.squareRoot(a);
Assert.assertEquals(Math.sqrt(a), result, DELTA);
}
@Test
public void testSquareRootWithNegativeNumber() {
a = -26665;
Double result = calculator.squareRoot(a);
Assert.assertNull(result);
}