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/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")