Add more Unit tests for the `languages` package

[andrii-bodnar]

The languages package has low code coverage by Unit tests. We need to add more Unit tests to cover the code.

References:

• Source code
• Existing Unit tests
• Actual coverage

[mslowiak]

Hi @andrii-bodnar 👋 Would you mind to assign this issue to myself?

[andrii-bodnar]

Hi @mslowiak, sure, thank you!