Improve docstring

Author: dandavison

temporalio/activity.py

@@ -279,18 +279,23 @@ def wait_sync(self, timeout: Optional[float] = None) -> None:
 def client() -> Client:
     """Return a Temporal Client for use in the current activity.
 
+    The client is only available in `async def` activities.
+
+    In tests it is not available automatically, but you can pass a client when creating a
+    :py:class:`temporalio.testing.ActivityEnvironment`.
+
     Returns:
         :py:class:`temporalio.client.Client` for use in the current activity.
 
     Raises:
-        RuntimeError: When not in an activity.
+        RuntimeError: When the client is not available.
     """
     client = _Context.current().client
     if not client:
         raise RuntimeError(
-            "No client available. The client is only available in async "
-            "(i.e. `async def`) activities; not in sync (i.e. `def`) activities. "
-            "In tests you can pass a client when creating ActivityEnvironment."
+            "No client available. The client is only available in `async def` "
+            "activities; not in `def` activities. In tests you can pass a "
+            "client when creating ActivityEnvironment."
         )
     return client
 

tests/worker/test_activity.py

@@ -97,9 +97,8 @@ async def get_name(name: str) -> str:
 async def test_client_available_in_async_activities(
     client: Client, worker: ExternalWorker
 ):
-    with pytest.raises(RuntimeError) as err:
+    with pytest.raises(RuntimeError, match="Not in activity context"):
         activity.client()
-    assert str(err.value) == "Not in activity context"
 
     captured_client: Optional[Client] = None
 
@@ -120,8 +119,8 @@ async def test_client_not_available_in_sync_activities(
     @activity.defn
     def some_activity() -> None:
         with pytest.raises(
-            RuntimeError, match="The client is only available in async"
-        ) as err:
+            RuntimeError, match="The client is only available in `async def`"
+        ):
             activity.client()
         nonlocal saw_error
         saw_error = True