Fix compatibility with Python 3.10, 3.9.11

A fix to 'importlib.metadata' in Python 3.10 [1], later backported to
3.9 and released in 3.9.11 [2], has broken our tests. Fix them.

[1] https://github.com/python/cpython/commit/b1e286860742e7ba6fadc75e3ddb6c2899a56919
[2] https://github.com/python/cpython/commit/177be52517da9a876a3f9e670f88c4731b906986

Signed-off-by: Stephen Finucane <stephenfin@redhat.com>
Closes-bug: #1966040
Change-Id: Iff536d4f4267efbebc4be1e7e5da8a9fde39f79b

1 files changed, 19 insertions, 11 deletions

diff --git a/stevedore/extension.py b/stevedore/extension.py
index 06ac067..d9ee084 100644
--- a/stevedore/extension.py
+++ b/stevedore/extension.py
@@ -61,17 +61,25 @@ class Extension(object):
     @property
     def extras(self):
         """The 'extras' settings for the plugin."""
-        # NOTE: The underlying package returns re.Match objects for
-        # some reason. Translate those to the matched strings, which
-        # seem more useful.
-        return [
-            # Python 3.6 returns _sre.SRE_Match objects. Later
-            # versions of python return re.Match objects. Both types
-            # have a 'string' attribute containing the text that
-            # matched the pattern.
-            getattr(e, 'string', e)
-            for e in self.entry_point.extras
-        ]
+        # NOTE: The underlying package returned re.Match objects until this was
+        # fixed in importlib-metadata 4.11.3. This was fixed in Python 3.10 and
+        # backported to Python 3.9.11. For older versions without this fix,
+        # translate the re.Match objects to the matched strings, which seem
+        # more useful.
+        extras = []
+        for extra in self.entry_point.extras:
+            if isinstance(extra, str):
+                # We were previously returning the whole string including
+                # backets. We need to continue doing so to preserve API
+                # compatibility.
+                extras.append(f'[{extra}]')
+            else:
+                # Python 3.6 returns _sre.SRE_Match objects. Later
+                # versions of python return re.Match objects. Both types
+                # have a 'string' attribute containing the text that
+                # matched the pattern.
+                extras.append(getattr(extra, 'string', extra))
+        return extras
 
     @property
     def attr(self):