ISD-2183 Add certificates integration tests

[Thanhphan1147]

Applicable spec: ISD163 (internal)

Add unit and integration tests for the new tls_relation module

Checklist

• The charm style guide was applied
• The contributing guide was applied
• The changes are compliant with ISD054 - Managing Charm Complexity
• The documentation is generated using src-docs
• The documentation for charmhub is updated
• The PR is tagged with appropriate label (urgent, trivial, complex)

[github-actions]

Test coverage for 85b3c71

Name                      Stmts   Miss Branch BrPart  Cover   Missing
---------------------------------------------------------------------
src/charm.py                 83     41     12      0    44%   71-72, 77-78, 83, 92-94, 103-106, 117-124, 131-132, 140-153, 157-159, 163-178
src/haproxy.py               47     10      2      1    78%   63, 71-72, 88-91, 101-103
src/state/config.py          40     22      6      0    39%   50-70, 85-93, 105-106
src/state/tls.py             38     12      6      1    61%   55-68, 91-96
src/state/validation.py      31     17      6      0    38%   59-75
src/tls_relation.py         117      2     18      1    96%   254-255, 263->266
---------------------------------------------------------------------
TOTAL                       356    104     50      3    66%

Static code analysis report

Run started:2024-10-14 10:11:42.665208

Test results:
  No issues identified.

Code scanned:
  Total lines of code: 1238
  Total lines skipped (#nosec): 0
  Total potential issues skipped due to specifically being disabled (e.g., #nosec BXXX): 3

Run metrics:
  Total issues (by severity):
  	Undefined: 0
  	Low: 0
  	Medium: 0
  	High: 0
  Total issues (by confidence):
  	Undefined: 0
  	Low: 0
  	Medium: 0
  	High: 0
Files skipped (0):

[amandahla]

LGTM

[alithethird]

Left 2 comments also you have a typo in src/haproxy.py s/haporxy/haproxy.
I have a couple more notes:
1- I think you can put the TLSInformation.validate() in a decorator. I think you can even put it in the validate_config_and_tls decorator and activate with a parameter like validate_info. You are calling it in 4 different functions.
2- Why use typing.cast(str, ...) instead of str(...)? As far as I know typing.cast() doesn't actually cast it, it just silences the mypy etc. doc

[Thanhphan1147]

Left 2 comments also you have a typo in src/haproxy.py s/haporxy/haproxy. I have a couple more notes: 1- I think you can put the TLSInformation.validate() in a decorator. I think you can even put it in the validate_config_and_tls decorator and activate with a parameter like validate_info. You are calling it in 4 different functions. 2- Why use typing.cast(str, ...) instead of str(...)? As far as I know typing.cast() doesn't actually cast it, it just silences the mypy etc. doc

I didn't put TLSInformation.validate() in a decorator because the hook was following the general flow of initializing the chamstate component for the hook -> do business logic and any errors will be caught and handled by the decorator. In cases where the return value of the charmstate component is not needed, then we'll use the validate() method of the charmstate component class. You can imagine different hooks can require any combination of charmstate components so putting all of them in a decorator and add a bunch of parameters is a bit messy. Also it doesn't make much sense if tls_information = TLSInformation.from_charm(self, self.certificates) and TLSInformation.validate(self) are in different places when they are functionally the same.

For typing.cast the main purpose for it is actually to tell mypy that at that point either the cert or the provider cert must exists

[alithethird]

LGTM 🚀