We can't tell you what the hidden test looks like since that would be unfair.
But do ignore the article_url attribute to develop your algorithm, since it is only provided for reference to read the entire story about how/when/where/why the image was circulated and should not be used to make your decision.
Also, a simple Ctrl+F for keyword snopes in the test file returns 485 matches, not sure how you're getting 810, please double check
Pro Tip: Your method would fail on hidden test set if you'd use article_url while developing your method, coz images can come from a lot of sources.