Add unit test that fails without the fix in previous commit

Author: julianstirling

src/labthings_fastapi/actions/__init__.py

@@ -19,7 +19,7 @@
     InvocationCancelledError,
     invocation_logger,
 )
-from ..outputs.blob import BlobIOContextDep
+from ..outputs.blob import BlobIOContextDep, blobdata_to_url_ctx
 
 if TYPE_CHECKING:
     # We only need these imports for type hints, so this avoids circular imports.
@@ -29,6 +29,14 @@
 ACTION_INVOCATIONS_PATH = "/action_invocations"
 
 
+class NoBlobManagerError(RuntimeError):
+    """Raised if an API route accesses Invocation outputs without a BlobIOContextDep.
+
+    Any access to an invocation output must have BlobIOContextDep as a dependency, as
+    the output may be a blob, and the blob needs this context to resolve its URL.
+    """
+
+
 class Invocation(Thread):
     """A Thread subclass that retains output values and tracks progress
 
@@ -89,6 +97,15 @@ def output(self) -> Any:
         """
         Return value of the Action. If the Action is still running, returns None.
         """
+        try:
+            blobdata_to_url_ctx.get()
+        except LookupError as e:
+            raise NoBlobManagerError(
+                "An invocation output has been requested from a api route that "
+                "doesn't have a BlobIOContextDep dependency. This dependency is needed "
+                " for blobs to identify their url."
+            ) from e
+
         with self._status_lock:
             return self._return_value
 

tests/test_actions.py

@@ -18,6 +18,30 @@ def run(payload=None):
     return run
 
 
+def test_get_action_invocations():
+    """Test that running "get" on an action returns a list of invocations."""
+    with TestClient(server.app) as client:
+        # When we start the action has no invocations
+        invocations_before = client.get("/thing/increment_counter").json()
+        assert invocations_before == []
+        # Start the action
+        r = client.post("/thing/increment_counter")
+        assert r.status_code in (200, 201)
+        # Now it is started, there is a list of 1 dictionary containing the
+        # invocation information.
+        invocations_after = client.get("/thing/increment_counter").json()
+        assert len(invocations_after) == 1
+        assert isinstance(invocations_after, list)
+        assert isinstance(invocations_after[0], dict)
+        assert "status" in invocations_after[0]
+        assert "id" in invocations_after[0]
+        assert "action" in invocations_after[0]
+        assert "href" in invocations_after[0]
+        assert "timeStarted" in invocations_after[0]
+        # Let the task finish before ending the test
+        poll_task(client, r.json())
+
+
 def test_counter():
     with TestClient(server.app) as client:
         before_value = client.get("/thing/counter").json()