fix: Remove WeakList in favor of built-ins

[matthewfeickert]

Description

Resolves #1506

Checklist Before Requesting Reviewer

• Tests are passing
• "WIP" removed from the title of the pull request
• Selected an Assignee for the PR to be responsible for the log summary

Before Merging

For the PR Assignees:

• Summarize commit messages into a comprehensive review of the PR

* Rewrite the events code to handle weakrefs more properly
   - This is needed to work with Click v8.0+
* Fix up tests that were incorrectly written due to API changes in unittest.mock

[matthewfeickert]

I think something is going wrong with the conftest(?) as I can trigger the errors seen in doctest locally with

$ python -m pytest -x -r sx --ignore tests/benchmarks/ --ignore tests/contrib --ignore tests/test_notebooks.py

src/pyhf/infer/utils.py ..                                                                                                                                                                          [  3%]
src/pyhf/tensor/jax_backend.py F

================================================================================================ FAILURES =================================================================================================
_________________________________________________________________________ [doctest] pyhf.tensor.jax_backend.jax_backend.astensor __________________________________________________________________________
201 
202         Convert to a JAX ndarray.
203 
204         Example:
205 
206             >>> import pyhf
207             >>> pyhf.set_backend("jax")
UNEXPECTED EXCEPTION: TypeError("'NoneType' object is not callable")
Traceback (most recent call last):
  File "/home/feickert/.pyenv/versions/3.8.6/lib/python3.8/doctest.py", line 1336, in __run
    exec(compile(example.source, filename, "single",
  File "<doctest pyhf.tensor.jax_backend.jax_backend.astensor[1]>", line 1, in <module>
  File "/home/feickert/Code/GitHub/pyhf/src/pyhf/events.py", line 122, in register_wrapper
    result = func(*args, **kwargs)
  File "/home/feickert/Code/GitHub/pyhf/src/pyhf/__init__.py", line 147, in set_backend
    events.trigger("tensorlib_changed")()
  File "/home/feickert/Code/GitHub/pyhf/src/pyhf/events.py", line 53, in __call__
    func()(*args, **kwargs)
TypeError: 'NoneType' object is not callable
/home/feickert/Code/GitHub/pyhf/src/pyhf/tensor/jax_backend.py:207: UnexpectedException

but

$ pytest -x --doctest-modules src/pyhf/infer/utils.py src/pyhf/tensor/numpy_backend.py src/pyhf/tensor/jax_backend.py

runs fine.

[codecov]

Codecov Report

Merging #1530 (ad9baf7) into master (29c3df0) will increase coverage by 0.03%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1530      +/-   ##
==========================================
+ Coverage   97.66%   97.70%   +0.03%     
==========================================
  Files          63       63              
  Lines        4024     4050      +26     
  Branches      572      576       +4     
==========================================
+ Hits         3930     3957      +27     
+ Misses         55       54       -1     
  Partials       39       39              

Flag	Coverage Δ
contrib	25.40% <27.27%> (-0.02%)	⬇️
unittests	97.48% <100.00%> (+0.04%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/pyhf/events.py	100.00% <100.00%> (+2.50%)	⬆️

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[kratsg]

Just putting a note that coverage needs to be fixed, but this is confirmed to work by @alexander-held .

[matthewfeickert]

Just putting a note that coverage needs to be fixed, but this is confirmed to work by @alexander-held .

Once this is in and we're happy with it working let's cut a v0.6.3 release so that this won't keep hitting cabinetry and the rest of our users. 👍

[matthewfeickert]

I'm sure that I'm missing the obvious here, but if this isn't already being hit anywhere in CI then what are the types of events that would trigger this?

The removal still passes CI and the following

# /tmp/test.py
import pyhf

model = pyhf.simplemodels.uncorrelated_background(
    signal=[5.0], bkg=[10.0], bkg_uncertainty=[2.0]
)

pyhf.set_backend("jax", "minuit")

model = pyhf.simplemodels.uncorrelated_background(
    signal=[5.0], bkg=[10.0], bkg_uncertainty=[2.0]
)

[matthewfeickert]

Highest of fives @kratsg. This is great. :)

Also thanks for these tests as this better shows me how to do things with Mock. 👍