Should this code be made testable?

Question

My code looks roughly like

40 def send_pubkey( s: socket ) -> None:                                           
41     '''Transmit own public key unencrypted.'''                                  
42     _, pub = crypto.read_keypair()                                              
43     s.sendall(pub.save_pkcs1())

This is extremely difficult to test as it involves network operations. However adding another level of abstraction between this layer and OS sockets goes against import this*. Any silver bullet out there?

_{* - Simple is better than complex.}

Thanks @candied_orange It still remains entirely unclear to me what the OP's actual objection is, particularly given "practicality beats purity". I think/hope we all know you can't actually define software engineering best practices in 20, or even 20,000 lines. OP: please clarify. — Philip Kendall, Jun 25 '23 at 16:20
@PhilipKendall my guess was going to be the flat over nested thing but you're right, the OP has left me guessing. — candied_orange, Jun 25 '23 at 16:22
@PhilipKendall Vorac has edited to define his import this concern. — candied_orange, Jun 26 '23 at 02:39
@candied_orange "In programming there is only one problem not solvable by introducing another abstraction layer: the problem of too many layers." — Vorac, Jun 26 '23 at 02:54

candied_orange · Accepted Answer · 2023-06-25T22:41:57.290

The way to make this code unit testable is not by mocking it. It's to give it a functional core.

def extract_pubkey( crypto ) -> bytes:
    _, pub = crypto.read_keypair() 
    return pub.save_pkcs1()

That is unit testable. It simplifies send_pubkey down to a one liner, if not out of existence. Yes it leaves the sending code not under unit test but that's as should be. Unit tests are about internal behavior. Not integration with the outside world.

score 3 · Answer 2 · answered Jun 25 '23 at 11:05

3

I would say no.

In these cases it's better to create a test environment (docker?) and actually send packets, integration rather than unit testing.

A unit test with a mocked network layer is going to be testing the mock to a large extent, and just wont pick up on lots of common networking errors.

answered Jun 25 '23 at 11:05

Ewan

75,506

+1 but sorry for changing the accepted answer. I got down to it just now and realized implementing a whole new layer(containers) is so much over my head. Thanks again, I'll keep Your wisdom in mind! – Vorac Aug 25 '23 at 05:52

Should this code be made testable?

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