Implementation of Unit test for CallLog service.

[thebelrobot]

443

Please complete the following steps and check these boxes before filing your PR:

Types of changes

• [ ] Bug fix (a change which fixes an issue)
• [ ] New feature (a change which adds functionality)
• [x] Unit test

Short description of what this resolves:

I have added unit test cases for CallLog service.

Checklist:

• [x] I have performed a self-review of my own code.
• [x] The code follows the style guidelines of this project.
• [x] The code changes are passing the CI checks
• [x] I have documented my code wherever required.
• [ ] The changes requires a change to the documentation.
• [ ] I have updated the documentation based on the my changes.
• [x] I have added tests to cover my changes (if not applicable, please state why)
• [x] All new and existing tests are passing.