A simple test connection with the "nc" tool using Robotframework? - frameworks

Question

I'm trying to execute a simple Test Connection test in Robotframework, between two IP addresses in the same network. What I'm trying to achieve is:
On one side
Execute Command echo Hello | nc -l 51111
to catch the "Hello" message on the other:
Execute Command 'nc ip 51111'
, using the standard netcat tool.
For this, I run the Test Script.robot:
Library Process
Library SSHLibrary
Suite Setup Open Connection And Log In
Suite Teardown Close All Connections
*** Variables ***
${HOST} ip.my.dev.vm
${USERNAME} user
${PASSWORD} password
${HOST_PDG} ip.server1
${HOST_IDPF} ip.server2
*** Test Cases ***
Step 1 Connect Server1 and send Hello to space
Open Connection And Log In Server1
${output}= Execute Command 'echo Hello | nc -l 51111'
Should Not Be Equal ${output} Hello
Step 2 Connect to Server2 and retrieve Hello
Open Connection And Log In Server2
${output}= Execute Command 'nc ip.server2 51111'
Should Be Equal ${output} Hello
*** Keywords ***
Open Connection And Log In
Open Connection ${HOST}
Login ${USERNAME} ${PASSWORD}
Open Connection And Log In Server1
Open Connection ${HOST_PDG}
Login ${USERNAME} ${PASSWORD}
Open Connection And Log In Server2
Open Connection ${HOST_IDPF}
Login ${USERNAME} ${PASSWORD}
This script stops after the first passed test step, and from the Server2 I never able to catch this Hello message.
The same test over command line with the nc tool works perfectly.
ssh Server1
echo Hello | nc -l 51111
ssh Server2
nc ip.server2 51111
(see the Hello message)
What is the problem to do it over the ROBOT Framework?
Thank you in advance!

Answer 1

The issue you're facing is because the robotframework execution is serial, while your aim implies parallelism - after running the netcat server on Server1, in parallel you want to connect to it from Server2.
This is what you're doing when you did it manually, but this is not what happened in the RF cases: in the framework, you've ran test 1, it did its steps, and finished (with some pass/fail status, but that's not important now). When it was done, the service was not running; so when in test 2 you tried to connect to it - it rightfully failed.
Here's what you can do - make the two steps (bringing up the service, and connecting to it) be executed in parallel. The easiest way is for that to be in the same case; and for the service to be running in the background you have to use not the Execute Command - which waits for its target to finish, but Start Command which starts it in the background immediately returns.
Its usage is a little bit different, in terms of getting the output and communicating with it, you can read how in the doc.

Answer 2

...and I found that...
Without changing the original script much, if the quotes around the both command are deleted, and Start Command is used instead of Execute Command, at the listener side (as Todor suggested, thank you!), the script will works as it is, giving the right results.