How to have less (scalp) flake with dependable tests
Be careful of flawed assertions in Cypress tests which can cause false positives and flakiness.
Achtung! Be careful of false positives when testing
The example I am going to give comes from a Cypress test suite.
A test was failing because it could not find the text it expected because the loading spinner was still in the document.
As can be seen in the above image, we think we are writing deliberate assertions that improve the tests robustness when in fact they aren’t doing anything and are false positives.
We make assertions on the loading spinner not being present so that we can be confident that the operation has completed and we can continue with our test. Unfortunately our method for asserting yields nothing which satisfies the check of “does not exist” and so undermines our confidence in the state of what is being tested. This is flakiness.
It is worth nothing that using findByLabelText should and would be the preferred option had we written our components with semantic HTML.