Test/app sentinel coverage

[gurkanguray]

App Sentinel Internal Unit tests added

Description

App Sentinel Internal Initialization Package's unit tests are added. Refactored the codebase for dependency injection and monkey patching.

Changes

List the major changes you have made in bullet points:

• Change 1
• Change 2
• Change 3

Test Policy Compliance

• I have added or updated unit tests for my changes.
• I have included integration tests where applicable.
• All new and existing tests pass successfully.

Code Quality

• I have followed the coding standards for this project.
• I have performed a self-review of my code.
• My code is well-commented, particularly in areas that may be difficult
  to understand.

Documentation

• I have made corresponding changes to the documentation (if applicable).
• I have updated any relevant READMEs or wiki pages.

Additional Comments

Include any additional comments or context about the PR here.

Checklist

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• You have read the contributing guidelines and
  especially the test policy.
• You have thoroughly tested your changes.
• You have followed all the contributing guidelines for this project.
• You understand and agree that your contributions will be publicly available
  under the project's license.

By submitting this pull request, you confirm that my contribution is made under
the terms of the project's license and that you have the authority to grant
these rights.

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[v0lkan]

Overall looking good.

At the very least, it's increasing coverage with minimal amount of code change; which is good.

Thanks a lot for the contribution @gurkanguray .

I'll merge it and run integration tests.

If we see an instability or test failure etc, I'll let you know.

Cheers.