assertTrue(errorCode.startsWith("error_code:"));
        assertTrue(errorCode.length() > 11); // "error_code:" is 11 chars
    }

    // Test with different exception types
    @Test
    public void test_exceptionTypes() {
        // Test RuntimeException
        RuntimeException runtimeEx = new RuntimeException("Runtime error");
        assertEquals("Runtime error", runtimeEx.getMessage());

        // Test Exception