test: add test case for pkg/sinks package

[amitamrutiya]

📑 Description

In this pull request, I added the necessary test cases for the pkg/sinks packages. The test coverage is as follows:

• Test coverage is 89.8% for the sinks package.

✅ Checks

• [X] My pull request adheres to the code style of this project
• [ ] My code requires changes to the documentation
• [ ] I have updated the documentation as required
• [X] All the tests have passed