// 定义一个测试类，用@Test注解标记要执行的测试方法public class CalculatorTest {

// 定义一个测试方法，用assertEquals方法来验证计算结果是否正确 @Test public void testAdd() { int result = calculateUsingStrategy(3, 5, "add"); assertEquals(8, result); }

// 定义其他的测试方法，分别测试不同的运算符和操作数 @Test public void testSubtract() { int result = calculateUsingStrategy(10, 4, "subtract"); assertEquals(6, result); }

@Test public void testMultiply() { int result = calculateUsingStrategy(7, 9, "multiply"); assertEquals(63, result); }

@Test public void testDivide() { int result = calculateUsingStrategy(12, 3, "divide"); assertEquals(4, result); }

// 定义一个测试方法，用assertThrows方法来验证抛出了预期的异常 @Test public void testDivideByZero() { assertThrows(ArithmeticException.class, () -> calculateUsingStrategy(10,0,"divide")); }

// 定义其他的测试方法，分别测试不同的异常情况

@Test public void testModulusByZero() { assertThrows(ArithmeticException.class, () -> calculateUsingStrategy(10,0,"modulus")); }

@Test public void testSquareRootOfNegativeNumber() { assertThrows(ArithmeticException.class, () -> calculateUsingStrategy(-4,-2,"square root")); }

// 定义一个测试方法，用assertThrows方法来验证抛出了预期的异常 @Test public void testInvalidOperator() { assertThrows(IllegalArgumentException.class, () -> calculateUsingStrategy(10,-2,"foo")); }}