帮我针对下这个测试方法生成junite的单元测试算法9测试is_num_constant方法：输入：一个字符串为数字常量预期输出：返回true输入：一个字符串不为数字常量预期输出：返回false

@Test public void testIsNumConstant() { String numConstant = "123"; boolean expectedResult = true; boolean actualResult = isNumConstant(numConstant); assertEquals(expectedResult, actualResult);

String notNumConstant = "abc";
expectedResult = false;
actualResult = isNumConstant(notNumConstant);
assertEquals(expectedResult, actualResult);

}

private boolean isNumConstant(String str) { try { Double.parseDouble(str); return true; } catch (NumberFormatException e) { return false; }