Need to improve the test coverage on rueidiscompat

[rueian]

Currently, we have poor test coverage on rueidiscompat:

Details of which lines are not covered can be found here: https://app.codecov.io/gh/redis/rueidis/tree/main/rueidiscompat

We hope that we can improve the coverage to be close to 100%.

[rueian]

Update the current coverage:

[arsentos]

@rueian Hello! Can i work on it?

[rueian]

Hi @arsentos, any help to improve the coverage is welcome. Thanks!