annotationlib: Improve test coverage

Feature or enhancement

Proposal:

The existing test suite for annotationlib is good, but there is still a decent amount of line/branch coverage missing. coverage.py reports 75% coverage, but this is mostly the library is already imported somewhere in coverage.py, so all global statements are marked as 'missing'.

Has this already been discussed elsewhere?

This is a minor feature, which does not need previous discussion elsewhere

Links to previous discussion of this feature:

No response

Linked PRs

gh-141174: Improve ForwardRef test coverage #141175
gh-141174: Improve annotationlib.call_annotate_function() test coverage #141176
gh-141174: Improve annotationlib._Stringifier test coverage #141220
gh-141174: Improve annotationlib.get_annotations() test coverage #141286
[3.14] gh-141174: Improve annotationlib.get_annotations() test coverage (GH-141286) #141353
[3.14] gh-141174: Improve ForwardRef test coverage (GH-141175) #141354
[3.14] gh-141174: Improve annotationlib.call_annotate_function() test coverage (GH-141176) #141355
[3.14] gh-141174: Improve annotationlib._Stringifier test coverage (GH-141220) #141358
gh-141174: Test type_repr() of Template with invalid syntax in Interpolation #155661
gh-141174: Test get_annotations() on wrapped cyclical functools.partial #155663
gh-141174: Test re-stringifying a ForwardRef #155689
[3.15] gh-141174: Test re-stringifying a ForwardRef (GH-155689) #155707
[3.14] gh-141174: Test re-stringifying a ForwardRef (GH-155689) #155708
[3.15] gh-141174: Test get_annotations() on wrapped cyclical functools.partial (GH-155663) #155709
[3.14] gh-141174: Test get_annotations() on wrapped cyclical functools.partial (GH-155663) #155710
[3.15] gh-141174: Test type_repr() of Template with invalid syntax in Interpolation (GH-155661) #155711
[3.14] gh-141174: Test type_repr() of Template with invalid syntax in Interpolation (GH-155661) #155712

@JelleZijlstra

Currently there is no coverage for the 'else' case in _build_closure():

cpython/Lib/annotationlib.py

Lines 842 to 845 in 14c6222

    
           if i < len(freevars): 
        
               name = freevars[i] 
        
           else: 
        
               name = "__cell__"

But I'm not sure what conditions would cause __closure__ and __code__.co_freevars to be different lengths.
Git blame says that @JelleZijlstra wrote this code, is there a particular object you'd expect to behave this way?

The only other place in the stdlib where both are used together is inspect.getclosurevars(), which simply zips the closure and freevars together:

cpython/Lib/inspect.py

Lines 1503 to 1509 in 14c6222

    
           if func.__closure__ is None: 
        
               nonlocal_vars = {} 
        
           else: 
        
               nonlocal_vars = { 
        
                   var : cell.cell_contents 
        
                   for var, cell in zip(code.co_freevars, func.__closure__) 
        
              }

I think that could only happen with a manually constructed code object (or if there's a bug in the compiler). I wrote it that way to make the code robust to this case, but it might have been better to throw an error instead if the lengths mismatch.

gh-141174: Improve `annotationlib.get_annotations()` test coverage (#…

pythongh-141174: Improve `annotationlib.get_annotations()` test cover…

gh-141174: Improve `ForwardRef` test coverage (#141175)

pythongh-141174: Improve `ForwardRef` test coverage (pythonGH-141175)

gh-141174: Improve `annotationlib.call_annotate_function()` test cove…

pythongh-141174: Improve `annotationlib.call_annotate_function()` tes…

gh-141174: Improve `annotationlib._Stringifier` test coverage (#141220)

pythongh-141174: Improve `annotationlib._Stringifier` test coverage (p…

[3.14] gh-141174: Improve `annotationlib.get_annotations()` test cove…

Probaly! Haven't looked at the tests recently, so will double-check over the next day.

gh-141174: Test re-stringifying a `ForwardRef` (#155689)

gh-141174: Test `get_annotations()` on wrapped cyclical `functools.pa…

gh-141174: Test `type_repr()` of `Template` with invalid syntax in `I…

[3.14] gh-141174: Test re-stringifying a `ForwardRef` (GH-155689) (#1…

[3.14] gh-141174: Test `type_repr()` of `Template` with invalid synta…

[3.14] gh-141174: Test `get_annotations()` on wrapped cyclical `funct…

Triage: Can this be clsoed as completed?

It's completed, for now, until new features get added to annotationlib which aren't tested properly.
But at that point it should be related to the specific feature, not to annotationlib as a whole, so I'll close this issue.

pythongh-141174: Test re-stringifying a `ForwardRef` (python#155689)

pythongh-141174: Test `get_annotations()` on wrapped cyclical `functo…

pythongh-141174: Test `type_repr()` of `Template` with invalid syntax…

[3.15] gh-141174: Test re-stringifying a `ForwardRef` (GH-155689) (#1…

[3.15] gh-141174: Test `type_repr()` of `Template` with invalid synta…

[3.15] gh-141174: Test `get_annotations()` on wrapped cyclical `funct…

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annotationlib: Improve test coverage #141174

Feature or enhancement

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Has this already been discussed elsewhere?

Links to previous discussion of this feature:

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	if i < len(freevars):
	name = freevars[i]
	else:
	name = "__cell__"

	if func.__closure__ is None:
	nonlocal_vars = {}
	else:
	nonlocal_vars = {
	var : cell.cell_contents
	for var, cell in zip(code.co_freevars, func.__closure__)
	}

annotationlib: Improve test coverage #141174

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Feature or enhancement

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Has this already been discussed elsewhere?

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dr-carlos commented on Nov 9, 2025

JelleZijlstra commented on Nov 10, 2025

11 remaining items

dr-carlos commented on Aug 12, 2026

dr-carlos commented on Aug 13, 2026

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