Implement equality constraint

[zenlyj]

Type of Changes

	Type
	🐛 Bug fix
✓	✨ New feature
	🔨 Refactoring
	📜 Docs

Description

Add a new EqualityConstraint to support narrowing of inferred values based on equality (==) and inequality (!=) comparisons.

The constraint currently handles:

• Comparison between constants
• Comparison between callables (e.g. classes, functions, lambdas)

Refs
pylint-dev/pylint#3632
pylint-dev/pylint#3633

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.31%. Comparing base (d4a7e63) to head (e369324).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2927      +/-   ##
==========================================
+ Coverage   93.29%   93.31%   +0.01%     
==========================================
  Files          92       92              
  Lines       11266    11292      +26     
==========================================
+ Hits        10511    10537      +26     
  Misses        755      755              

Flag	Coverage Δ
linux	93.17% <100.00%> (+0.01%)	⬆️
pypy	93.31% <100.00%> (+0.01%)	⬆️
windows	93.29% <100.00%> (+0.01%)	⬆️

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

Files with missing lines	Coverage Δ
astroid/constraint.py	100.00% <100.00%> (ø)

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[zenlyj]

The referenced issues are no longer flagged by pylint, probably due to the use of safe_infer(). However, the following false positive is still present:

"""docstring"""

class PV1Axis():
    """Single-axis tracking PV."""
    def __init__(self, polygon, capacity, filename, column, build_limit=None, label='PV'):
        pass

class Biofuel():
    """Model of open cycle gas turbines burning biofuel."""
    def __init__(self, polygon, capacity, label='biofuel'):
        pass

g = PV1Axis
if g == Biofuel:
    g(0, 100)  # E1120: No value for argument 'filename'/'column' in constructor call (no-value-for-parameter)

[DanielNoord]

@jacobtylerwalls Do you have time to review this? I consider you domain expert on the constraints.

It LGTM, but I might be missing something.

Thanks @zenlyj for this PR!

[jacobtylerwalls]

Thanks 👍

I was sitting on this one for a bit because I thought I might resuscitate my effort to adding a github workflow to run the pylint primer on astroid PRs, but I just didn't get there yet.

[jacobtylerwalls]

Thanks 👍, just a teeny polish question.

[jacobtylerwalls]

Is there a pytest-idiomatic way to show the node that failed in the assertion?

[Pierre-Sassoulas]

I usually add info about the node in the assert message when doing this

[zenlyj]

Good point, I've added some info to identify the node that fails. The message looks something like this:

Let me know if the message needs to be refined

[jacobtylerwalls]

Thanks!