@Test
public void test_executeNegative() throws Exception {
Operation operation = new SubtractOperation(BigDecimal.valueOf(1));
BigDecimal result = operation.execute(BigDecimal.valueOf(-3)); // -3 - 1
assertTrue(result.compareTo(BigDecimal.valueOf(-4)) == 0);
}
@Test(expected = NullPointerException.class)
public void test_executeNull_NullPointerException() throws Exception {
Operation operation = new SubtractOperation(BigDecimal.valueOf(2));
operation.execute(null);
}