OK kiddo, let me tell you about something called a purity test in politics. It's kinda like a quiz they take to see how good of a politician they are, but it's not really about being smart or knowing a lot of things.
It's more like a test to see how closely they follow the beliefs and values of their political party. See, different political parties have different ideas about what's important and what they want to do, so the purity test is like a way for a politician to show that they're on the same page as the party they belong to.
They might get asked questions about things like taxes, or gun control, or healthcare, and their answers have to match up with what their party thinks. If they don't agree, they might not do very well on the purity test and their party might not be very happy with them.
Some people think that purity tests are bad because they can keep politicians from thinking for themselves or being independent. They might feel like they have to go along with whatever their party says, instead of making their own decisions based on what they think is best.
But others think that purity tests are a good thing because they help make sure that everyone in a party is working towards the same goal. It can make it easier to get things done if everyone agrees on what they want to do.
So that's the basics of what a purity test is in politics. It's not really about being pure or being a perfect politician, it's more about seeing how well someone fits in with their party. Does that make sense?