test-backend: Remove rate_limiter from not_yet_fully_covered.

rate_limiter.py now has sufficient test coverage to remove from the
list of exclusions.

Tweaked by tabbott to handle @abstractmethod in a better way.

tools/coveragerc

@@ -15,6 +15,8 @@ exclude_lines =
     raise UnexpectedWebhookEventType
     # Don't require coverage for blocks only run when type-checking
     if TYPE_CHECKING:
+    # Don't require coverage for abstract methods; they're never called.
+    @abstractmethod
     # Don't require coverage for the settings.LOG_API_EVENT_TYPES code paths
     # These are only run in a special testing mode, so will fail normal coverage.
     if settings.LOG_API_EVENT_TYPES:

tools/test-backend

@@ -93,7 +93,6 @@ not_yet_fully_covered = {path for target in [
     'zerver/lib/parallel.py',
     'zerver/lib/profile.py',
     'zerver/lib/queue.py',
-    'zerver/lib/rate_limiter.py',
     'zerver/lib/sqlalchemy_utils.py',
     'zerver/lib/storage.py',
     'zerver/lib/stream_recipient.py',

zerver/lib/rate_limiter.py

@@ -369,7 +369,7 @@ class RedisRateLimiterBackend(RateLimiterBackend):
 
         if key_blocked is not None:
             # We are manually blocked. Report for how much longer we will be
-            if blocking_ttl_b is None:
+            if blocking_ttl_b is None:  # nocoverage # defensive code, this should never happen
                 blocking_ttl = 0.5
             else:
                 blocking_ttl = int(blocking_ttl_b)
@@ -436,7 +436,7 @@ class RedisRateLimiterBackend(RateLimiterBackend):
 
                     # If no exception was raised in the execution, there were no transaction conflicts
                     break
-                except redis.WatchError:
+                except redis.WatchError:  # nocoverage # Ideally we'd have a test for this.
                     if count > 10:
                         raise RateLimiterLockingException()
                     count += 1

zerver/tests/test_rate_limiter.py

@@ -83,7 +83,7 @@ class RateLimiterBackendBase(ZulipTestCase):
         """
         This depends on the algorithm used in the backend, and should be defined by the test class.
         """
-        raise NotImplementedError  # nocoverage
+        raise NotImplementedError()
 
     def test_hit_ratelimits(self) -> None:
         obj = self.create_object('test', [(2, 3), ])