Issue #15767: Introduce ModuleNotFoundError, a subclass of
ImportError.
The exception is raised by import when a module could not be found.
Technically this is defined as no viable loader could be found for the
specified module. This includes ``from ... import`` statements so that
the module usage is consistent for all situations where import
couldn't find what was requested.
This should allow for the common idiom of::
try:
import something
except ImportError:
pass
to be updated to using ModuleNotFoundError and not accidentally mask
ImportError messages that should propagate (e.g. issues with a
loader).
This work was driven by the fact that the ``from ... import``
statement needed to be able to tell the difference between an
ImportError that simply couldn't find a module (and thus silence the
exception so that ceval can raise it) and an ImportError that
represented an actual problem.
diff --git a/Lib/importlib/_bootstrap.py b/Lib/importlib/_bootstrap.py
index e477b55..cd41336 100644
--- a/Lib/importlib/_bootstrap.py
+++ b/Lib/importlib/_bootstrap.py
@@ -1553,11 +1553,7 @@
raise ImportError(msg, name=name)
loader = _find_module(name, path)
if loader is None:
- exc = ImportError(_ERR_MSG.format(name), name=name)
- # TODO(brett): switch to a proper ModuleNotFound exception in Python
- # 3.4.
- exc._not_found = True
- raise exc
+ raise ModuleNotFoundError(_ERR_MSG.format(name), name=name)
elif name not in sys.modules:
# The parent import may have already imported this module.
loader.load_module(name)
@@ -1643,15 +1639,12 @@
from_name = '{}.{}'.format(module.__name__, x)
try:
_call_with_frames_removed(import_, from_name)
- except ImportError as exc:
+ except ModuleNotFoundError as exc:
# Backwards-compatibility dictates we ignore failed
# imports triggered by fromlist for modules that don't
# exist.
- # TODO(brett): In Python 3.4, have import raise
- # ModuleNotFound and catch that.
- if getattr(exc, '_not_found', False):
- if exc.name == from_name:
- continue
+ if exc.name == from_name:
+ continue
raise
return module
diff --git a/Lib/pydoc.py b/Lib/pydoc.py
index 3f6fdf0..6a2b44a 100755
--- a/Lib/pydoc.py
+++ b/Lib/pydoc.py
@@ -317,7 +317,7 @@
elif exc is SyntaxError:
# A SyntaxError occurred before we could execute the module.
raise ErrorDuringImport(value.filename, info)
- elif exc is ImportError and value.name == path:
+ elif issubclass(exc, ImportError) and value.name == path:
# No such module in the path.
return None
else:
diff --git a/Lib/test/exception_hierarchy.txt b/Lib/test/exception_hierarchy.txt
index 1c1f69f..88e1b81 100644
--- a/Lib/test/exception_hierarchy.txt
+++ b/Lib/test/exception_hierarchy.txt
@@ -13,6 +13,7 @@
+-- BufferError
+-- EOFError
+-- ImportError
+ +-- ModuleNotFoundError
+-- LookupError
| +-- IndexError
| +-- KeyError
diff --git a/Lib/test/test_exceptions.py b/Lib/test/test_exceptions.py
index 2f39d4b..f0851bd 100644
--- a/Lib/test/test_exceptions.py
+++ b/Lib/test/test_exceptions.py
@@ -953,8 +953,5 @@
self.assertEqual(str(arg), str(exc))
-def test_main():
- run_unittest(ExceptionTests, ImportErrorTests)
-
if __name__ == '__main__':
unittest.main()
diff --git a/Lib/test/test_import.py b/Lib/test/test_import.py
index 9c14e15..805e9ed 100644
--- a/Lib/test/test_import.py
+++ b/Lib/test/test_import.py
@@ -68,7 +68,15 @@
def tearDown(self):
unload(TESTFN)
- setUp = tearDown
+ def test_import_raises_ModuleNotFoundError(self):
+ with self.assertRaises(ModuleNotFoundError):
+ import something_that_should_not_exist_anywhere
+
+ def test_from_import_raises_ModuleNotFoundError(self):
+ with self.assertRaises(ModuleNotFoundError):
+ from something_that_should_not_exist_anywhere import blah
+ with self.assertRaises(ModuleNotFoundError):
+ from importlib import something_that_should_not_exist_anywhere
def test_case_sensitivity(self):
# Brief digression to test that import is case-sensitive: if we got
@@ -487,7 +495,7 @@
header = f.read(12)
code = marshal.load(f)
constants = list(code.co_consts)
- foreign_code = test_main.__code__
+ foreign_code = importlib.import_module.__code__
pos = constants.index(1)
constants[pos] = foreign_code
code = type(code)(code.co_argcount, code.co_kwonlyargcount,
@@ -1014,16 +1022,5 @@
importlib.SourceLoader.load_module = old_load_module
-def test_main(verbose=None):
- run_unittest(ImportTests, PycacheTests, FilePermissionTests,
- PycRewritingTests, PathsTests, RelativeImportTests,
- OverridingImportBuiltinTests,
- ImportlibBootstrapTests,
- TestSymbolicallyLinkedPackage,
- ImportTracebackTests)
-
-
if __name__ == '__main__':
- # Test needs to be a package, so we can do relative imports.
- from test.test_import import test_main
- test_main()
+ unittest.main()
diff --git a/Lib/test/test_importlib/import_/test_api.py b/Lib/test/test_importlib/import_/test_api.py
index 3d4cd94..6aca6dc 100644
--- a/Lib/test/test_importlib/import_/test_api.py
+++ b/Lib/test/test_importlib/import_/test_api.py
@@ -22,6 +22,10 @@
"""Test API-specific details for __import__ (e.g. raising the right
exception when passing in an int for the module name)."""
+ def test_raises_ModuleNotFoundError(self):
+ with self.assertRaises(ModuleNotFoundError):
+ util.import_('some module that does not exist')
+
def test_name_requires_rparition(self):
# Raise TypeError if a non-string is passed in for the module name.
with self.assertRaises(TypeError):
diff --git a/Lib/test/test_importlib/import_/test_fromlist.py b/Lib/test/test_importlib/import_/test_fromlist.py
index c16c337..9aa27a0 100644
--- a/Lib/test/test_importlib/import_/test_fromlist.py
+++ b/Lib/test/test_importlib/import_/test_fromlist.py
@@ -69,16 +69,16 @@
self.assertTrue(hasattr(module, 'module'))
self.assertEqual(module.module.__name__, 'pkg.module')
- def test_module_from_package_triggers_ImportError(self):
- # If a submodule causes an ImportError because it tries to import
- # a module which doesn't exist, that should let the ImportError
+ def test_module_from_package_triggers_ModuleNotFoundError(self):
+ # If a submodule causes an ModuleNotFoundError because it tries to import
+ # a module which doesn't exist, that should let the ModuleNotFoundError
# propagate.
def module_code():
import i_do_not_exist
with util.mock_modules('pkg.__init__', 'pkg.mod',
module_code={'pkg.mod': module_code}) as importer:
with util.import_state(meta_path=[importer]):
- with self.assertRaises(ImportError) as exc:
+ with self.assertRaises(ModuleNotFoundError) as exc:
import_util.import_('pkg', fromlist=['mod'])
self.assertEqual('i_do_not_exist', exc.exception.name)
diff --git a/Lib/test/test_pydoc.py b/Lib/test/test_pydoc.py
index 399f818..95ef115 100644
--- a/Lib/test/test_pydoc.py
+++ b/Lib/test/test_pydoc.py
@@ -206,7 +206,7 @@
missing_pattern = "no Python documentation found for '%s'"
# output pattern for module with bad imports
-badimport_pattern = "problem in %s - ImportError: No module named %r"
+badimport_pattern = "problem in %s - ModuleNotFoundError: No module named %r"
def run_pydoc(module_name, *args, **env):
"""
diff --git a/Lib/test/test_site.py b/Lib/test/test_site.py
index 9c7840f..06d7bd7 100644
--- a/Lib/test/test_site.py
+++ b/Lib/test/test_site.py
@@ -131,7 +131,7 @@
re.escape(os.path.join(pth_dir, pth_fn)))
# XXX: ditto previous XXX comment.
self.assertRegex(err_out.getvalue(), 'Traceback')
- self.assertRegex(err_out.getvalue(), 'ImportError')
+ self.assertRegex(err_out.getvalue(), 'ModuleNotFoundError')
@unittest.skipIf(sys.platform == "win32", "Windows does not raise an "
"error for file paths containing null characters")