Enable addtional flake8-bugbear linting checks. (#9659)

changelog.d/9659.misc

@@ -0,0 +1 @@
+Introduce bugbear to the test suite and fix some of it's lint violations.

setup.cfg

@@ -18,8 +18,8 @@ ignore =
 #  E203: whitespace before ':' (which is contrary to pep8?)
 #  E731: do not assign a lambda expression, use a def
 #  E501: Line too long (black enforces this for us)
-#   B00: Subsection of the bugbear suite (TODO: add in remaining fixes)
-ignore=W503,W504,E203,E731,E501,B00
+#  B00*: Subsection of the bugbear suite (TODO: add in remaining fixes)
+ignore=W503,W504,E203,E731,E501,B006,B007,B008
 
 [isort]
 line_length = 88

synapse/crypto/context_factory.py

@@ -191,7 +191,7 @@ def _context_info_cb(ssl_connection, where, ret):
         # ... we further assume that SSLClientConnectionCreator has set the
         # '_synapse_tls_verifier' attribute to a ConnectionVerifier object.
         tls_protocol._synapse_tls_verifier.verify_context_info_cb(ssl_connection, where)
-    except:  # noqa: E722, taken from the twisted implementation
+    except BaseException:  # taken from the twisted implementation
         logger.exception("Error during info_callback")
         f = Failure()
         tls_protocol.failVerification(f)

synapse/logging/context.py

@@ -689,7 +689,7 @@ def run_in_background(f, *args, **kwargs) -> defer.Deferred:
     current = current_context()
     try:
         res = f(*args, **kwargs)
-    except:  # noqa: E722
+    except Exception:
         # the assumption here is that the caller doesn't want to be disturbed
         # by synchronous exceptions, so let's turn them into Failures.
         return defer.fail()

synapse/storage/database.py

@@ -670,7 +670,7 @@ class DatabasePool:
 
             for after_callback, after_args, after_kwargs in after_callbacks:
                 after_callback(*after_args, **after_kwargs)
-        except:  # noqa: E722, as we reraise the exception this is fine.
+        except Exception:
             for after_callback, after_args, after_kwargs in exception_callbacks:
                 after_callback(*after_args, **after_kwargs)
             raise

synapse/util/async_helpers.py

@@ -496,7 +496,7 @@ def timeout_deferred(
 
         try:
             deferred.cancel()
-        except:  # noqa: E722, if we throw any exception it'll break time outs
+        except Exception:  # if we throw any exception it'll break time outs
             logger.exception("Canceller failed during timeout")
 
         # the cancel() call should have set off a chain of errbacks which

synapse/util/caches/__init__.py

@@ -116,7 +116,7 @@ def register_cache(
     """
     if resizable:
         if not resize_callback:
-            resize_callback = getattr(cache, "set_cache_factor")
+            resize_callback = cache.set_cache_factor  # type: ignore
         add_resizable_cache(cache_name, resize_callback)
 
     metric = CacheMetric(cache, cache_type, cache_name, collect_callback)

tests/server.py

@@ -593,7 +593,7 @@ class FakeTransport:
         if self.disconnected:
             return
 
-        if getattr(self.other, "transport") is None:
+        if not hasattr(self.other, "transport"):
             # the other has no transport yet; reschedule
             if self.autoflush:
                 self._reactor.callLater(0.0, self.flush)