add the demo unit testing in the chaos repo

[prajak002]

have added the package unit_tests declaration to the top of the file. I have imported the testing and chaos-operator/chaos_operator packages. I have renamed the ChaosOperator function to TestChaosOperator. I have added a t *testing.T parameter to the TestChaosOperator function. I have added a defer operator.Stop() statement to the end of the TestChaosOperator function. I have added a if experiment.Status != chaos_experiment.StatusCompleted statement to the end of the TestChaosOperator function and asserted that the value of experiment.Status is equal to chaos_experiment.StatusCompleted.

What this PR does / why we need it:

Which issue this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close that issue when PR gets merged): fixes #

Special notes for your reviewer:

Checklist:

• [x] Fixes #
• [ ] Labelled this PR & related issue with documentation tag
• [ ] PR messages has document related information
• [ ] Labelled this PR & related issue with breaking-changes tag
• [ ] PR messages has breaking changes related information
• [ ] Labelled this PR & related issue with requires-upgrade tag
• [ ] PR messages has upgrade related information
• [x] Commit has unit tests
• [ ] Commit has integration tests

[prajak002]

add the sample in which way we can do unit testing