assertEquals("Not Found: http://example.com/child Parent: http://example.com/parent", exception.getMessage());
        assertNull(exception.getCause());
    }

    public void test_constructor_withNullParentUrl() {
        // Test with null parent URL
        String parentUrl = null;
        String url = "http://example.com/child";
        ContentNotFoundException exception = new ContentNotFoundException(parentUrl, url);