update jest to latest version

[guumaster]

when using jest@latest (currently v27) test suites brake with this error:

 Test functions cannot both take a 'done' callback and return something. Either use a 'done' callback, or return a promise.

several tests needs to be reviewed.

[yahia-kerim]

The new 27.x version does not support done callback and async test simultaneously (see this: jestjs/jest#10529).

As we are using both of them in event-based tests (e.g: to test synchronize method), we need to refactor those them so we can test those methods with one of the two (done callback or async).

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.