Create mock tests

[selfuryon]

Need to create mock tests for fast developing otherwise I need to test all classes after each significant commit to base classes. It's too hard and I can't use it in CI/CD

[selfuryon]

Need to think about how to do it. Just create a file which class will be read line-by-line? Or something else.

[selfuryon]

I want to read a particular file when running a particular command, so I'll have files like these:

• show_run.txt
• show_ver
• etc

So when the code needs to run show run command it should read show_run.txt file.

Some thoughts:

• mock establish_connection() for reading only text files without real ssh connections
• mock send_command() and send_config_set() for getting the right file
• maybe need to mock read_until_pattern()

[selfuryon]

The main goal is to replace self._stdin and self._stdout. I need to create a similar interface like SSHClientSession