Add more unit tests to cover more edge cases

[aniketsharma00411]

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All edge cases are not covered by current unit tests thus more unit tests should be added to cover those.

All methods currently have atleast one unit test for them and all tests for a method should be present in the same file.

Note: This issue will not be assigned to anyone but anyone can work on it. Just create a pull request mentioning the issue and what edge cases you covered which were not previously checked. This issue will not be closed.