Codesling heavily utilizes snapshot testing across the board to help with maintainability of unit and integration tests. Currently, there are no end-to-end tests.
If you've never heard of snapshot testing, check these 2 resources:
Jest Snapshots and Beyond Snapshot Testing with Jest
__snapshots__ directories are intended to be committed to source control.
When modifying a test case or changing the behavior of a unit that affects a test case, you'll notice that the snapshot test (yarn test) will fail.
When it fails, you can choose to update the snapshot by passing in the -u flag to the testing command. You should only update a snapshot test if the intended behavior of the unit being tested or the test case itself is changing.
In order to update a snapshot, you will need to pass the -u flag. However, because we are using npm scripts to run the individual jest commands, we will need to pass along the flag from the npm script into jest:
$ yarn test -- -- -u # when running from the project root
$ yarn test -- -u # when running from individual server/service