Given a test like this one:
Something like this may pass in your code… but it is not testing
what you think it is testing. There is a typo in the second expectation,
so of course it is not going to find
[data-search-resutls], regardless of
whether your app is working as intended or not.
To avoid this situation, I always put the thing to look for (in this case the CSS selector) in a variable, and then I use this variable for both the test of existence and the test of non-existence:
This way, a typo will make the first expectation fail, and the issue will be made evident.
It is important that there is also a test of existence (first expectation in this example). It does not matter if this is as an assertion/expectation in the same test, or in a separate one. Having only a test that checks for non-existence of something can be misleading for the same reason: your target may not be present for completely different reasons from what you expect.