To run the Telnet library acceptance tests you will need to have a telnet
server running at localhost and accepting login from user test with password
test. Needless to say, you probably don't want this server to be visible to
public internet.
The user test is also assumed to have home directory at /home/test and
prompt set at PS1='\u@\h \W \$ '. These are defaults at least on Debian
based systems.
Telnet library has an optional dependency to pyte module to support
terminal emulation. It is needed to make all tests pass and can be installed
with the familiar pip install pyte command.