Agree, that check is not related to the real purpose of this test.
Having this additional check will make the test fail if someone changes the predicate in some way, and I see it as a quick way to tell people that there is a test covering the feature: "I changed this and broke a test... Let's see if my changes have more implications..." or "Oh, there is a test for this! Perhaps I should add mines to that class..."
WDYT?