doctest.testmod(empty_package) raises TypeError in 3.7 (and no errors in 3.6) #80587
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In recent Python, a directory without __init__.py is also a package, and hence can be imported. When this directory/package is empty, and a doctest.testmod() is executed, the behaviour changed from 3.6 to 3.7, which I didn't find in the "what's new" documentation. Minimal example:
>>> import doctest, os
>>> os.mkdir('empty_package')
>>> import empty_package
>>> doctest.testmod(empty_package)Python 3.6.8 on Windows 7 prints Python 3.7.2 on Windows 7 raises below TypeError in doctest
Traceback (most recent call last):
File "bug_empty_package.py", line 4, in <module>
print(doctest.testmod(empty_package))
File "...\Python37\lib\doctest.py", line 1949, in testmod
for test in finder.find(m, name, globs=globs, extraglobs=extraglobs):
File "...\Python37\lib\doctest.py", line 932, in find
self._find(tests, obj, name, module, source_lines, globs, {})
File "...\Python37\lib\doctest.py", line 982, in _find
test = self._get_test(obj, name, module, globs, source_lines)
File "...\Python37\lib\doctest.py", line 1063, in _get_test
if filename[-4:] == ".pyc":
TypeError: 'NoneType' object is not subscriptable |
Dutcho
mannequin
added
3.7 (EOL)
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This might be due to changes introduced in a23d30f where __file__ is set to None. Hence the below returns None but before the commit this used to return an AttributeError and print "missing" . This was not handled in doctest causing error. Adding Barry for confirmation. # foo.py import empty_package
print(getattr(empty_package, '__file__', 'missing'))➜ cpython git:(2b5937e) ✗ git checkout a23d30f && make -s -j4 > /dev/null There is a unittest with empty package and it's just that doctest.testmod(mod) was not called on the empty package causing this not to be found. A simple patch would be to check for None where None is a valid value for DocTest. Another possible fix would be to have module.__name__ for None but since this is for empty packages I assume there won't be any doctest to parse in DocTest constructor. diff --git a/Lib/doctest.py b/Lib/doctest.py
index 79d91a040c..e97555ed2f 100644
--- a/Lib/doctest.py
+++ b/Lib/doctest.py
@@ -1060,7 +1060,7 @@ class DocTestFinder:
filename = None
else:
filename = getattr(module, '__file__', module.__name__)
- if filename[-4:] == ".pyc":
+ if filename and filename[-4:] == ".pyc":
filename = filename[:-1]
return self._parser.get_doctest(docstring, globs, name,
filename, lineno)
diff --git a/Lib/test/test_doctest.py b/Lib/test/test_doctest.py
index f1013f2572..b99f2aea2f 100644
--- a/Lib/test/test_doctest.py
+++ b/Lib/test/test_doctest.py
@@ -699,6 +699,7 @@ class TestDocTestFinder(unittest.TestCase):
support.forget(pkg_name)
sys.path.pop()
assert doctest.DocTestFinder().find(mod) == []
+ doctest.testmod(mod) def test_DocTestParser(): r"""Without patch the line doctest.testmod(mod) in unittest fails as below with TypeError and with patch the tests pass $ ./python.exe Lib/test/test_doctest.py
doctest (doctest) ... 66 tests with zero failures
doctest (test.test_doctest) ... 516 tests with zero failures
test_empty_namespace_package (__main__.TestDocTestFinder) ... ERROR====================================================================== Traceback (most recent call last):
File "Lib/test/test_doctest.py", line 702, in test_empty_namespace_package
doctest.testmod(mod)
File "/Users/karthikeyansingaravelan/stuff/python/cpython/Lib/doctest.py", line 1947, in testmod
for test in finder.find(m, name, globs=globs, extraglobs=extraglobs):
File "/Users/karthikeyansingaravelan/stuff/python/cpython/Lib/doctest.py", line 932, in find
self._find(tests, obj, name, module, source_lines, globs, {})
File "/Users/karthikeyansingaravelan/stuff/python/cpython/Lib/doctest.py", line 982, in _find
test = self._get_test(obj, name, module, globs, source_lines)
File "/Users/karthikeyansingaravelan/stuff/python/cpython/Lib/doctest.py", line 1063, in _get_test
if filename[-4:] == ".pyc":
TypeError: 'NoneType' object is not subscriptableRan 1 test in 0.027s FAILED (errors=1)
Traceback (most recent call last):
File "Lib/test/test_doctest.py", line 3032, in <module>
test_main()
File "Lib/test/test_doctest.py", line 3015, in test_main
support.run_unittest(__name__)
File "/Users/karthikeyansingaravelan/stuff/python/cpython/Lib/test/support/__init__.py", line 2064, in run_unittest
_run_suite(suite)
File "/Users/karthikeyansingaravelan/stuff/python/cpython/Lib/test/support/__init__.py", line 1983, in _run_suite
raise TestFailed(err)
test.support.TestFailed: Traceback (most recent call last):
File "Lib/test/test_doctest.py", line 702, in test_empty_namespace_package
doctest.testmod(mod)
File "/Users/karthikeyansingaravelan/stuff/python/cpython/Lib/doctest.py", line 1947, in testmod
for test in finder.find(m, name, globs=globs, extraglobs=extraglobs):
File "/Users/karthikeyansingaravelan/stuff/python/cpython/Lib/doctest.py", line 932, in find
self._find(tests, obj, name, module, source_lines, globs, {})
File "/Users/karthikeyansingaravelan/stuff/python/cpython/Lib/doctest.py", line 982, in _find
test = self._get_test(obj, name, module, globs, source_lines)
File "/Users/karthikeyansingaravelan/stuff/python/cpython/Lib/doctest.py", line 1063, in _get_test
if filename[-4:] == ".pyc":
TypeError: 'NoneType' object is not subscriptable |
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So this was backported to 3.6 too with but caused similar issues reported in bpo-32872 to be reverted back. |
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A subscriptable object is any object that implements the __getitem__ special method (think lists, dictionaries). It is an object that records the operations done to it and it can store them as a "script" which can be replayed. You are trying to subscript an object which you think is a list or dict, but actually is None. NoneType is the type of the None object which represents a lack of value, for example, a function that does not explicitly return a value will return None. 'NoneType' object is not subscriptable is the one thrown by python when you use the square bracket notation object[key] where an object doesn't define the __getitem__ method . You might have noticed that the method sort() that only modify the list have no return value printed – they return the default None. This is a design principle for all mutable data structures in Python. http://net-informations.com/python/err/nonetype.htm |
Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.
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