fix: suppress exceptions when finding source= modules. #1203

CHANGES.rst

@@ -22,6 +22,12 @@ This list is detailed and covers changes in each pre-release version.
 Unreleased
 ----------
 
+- Fix: A module specified as the ``source`` setting is imported during startup,
+  before the user program imports it.  This could cause problems if the rest of
+  the program isn't ready yet.  For example, `issue 1203`_ describes a Django
+  setting that is accessed before settings have been configured.  Now that
+  early import is wrapped in a try/except so the error doesn't stop execution.
+
 - Fix: A colon in a decorator expression would cause an exclusion to end too
   early, preventing the exclusion of the decorated function. This is now fixed.
 
@@ -31,6 +37,8 @@ Unreleased
 - Debug: The `coverage debug data` command will now sniff out combinable data
   files, and report on all of them.
 
+.. _issue 1203: https://github.com/nedbat/coveragepy/issues/1203
+
 
 .. _changes_612:
 

coverage/inorout.py

@@ -120,7 +120,7 @@ def file_and_path_for_module(modulename):
     path = []
     try:
         spec = importlib.util.find_spec(modulename)
-    except ImportError:
+    except Exception:
         pass
     else:
         if spec is not None:

doc/source.rst

@@ -46,6 +46,8 @@ scratch files written by text editors). Files that do not end with ``.py``,
     isn't a problem, but could cause trouble if a module has side-effects at
     import time.
 
+    Exceptions during the early import are suppressed and ignored.
+
 You can further fine-tune coverage.py's attention with the ``--include`` and
 ``--omit`` switches (or ``[run] include`` and ``[run] omit`` configuration
 values). ``--include`` is a list of file name patterns. If specified, only