Improve test coverage of endpoint decorator

I test for an error condition, and also test using the
endpoint functions not via HTTP.

It was necessary to add a default value for Thing.path to make
sure we raise the right error - this is needed by other checks
that are introduced in #180.

Author: rwb27

src/labthings_fastapi/thing.py

@@ -77,7 +77,7 @@ class Thing:
     """A human-readable description of the Thing"""
     _labthings_blocking_portal: Optional[BlockingPortal] = None
     """See :ref:`concurrency` for why blocking portal is needed."""
-    path: Optional[str]
+    path: Optional[str] = None
     """The path at which the `.Thing` is exposed over HTTP."""
 
     async def __aenter__(self) -> Self:

tests/test_endpoint_decorator.py

@@ -1,39 +1,64 @@
 from fastapi.testclient import TestClient
-from labthings_fastapi import ThingServer, Thing, fastapi_endpoint
 from pydantic import BaseModel
+import pytest
+import labthings_fastapi as lt
 
 
 class PostBodyModel(BaseModel):
     a: int
     b: int
 
 
-class TestThing(Thing):
-    @fastapi_endpoint("get")
+class MyThing(lt.Thing):
+    @lt.fastapi_endpoint("get")
     def path_from_name(self) -> str:
         return "path_from_name"
 
-    @fastapi_endpoint("get", path="path_from_path")
+    @lt.fastapi_endpoint("get", path="path_from_path")
     def get_method(self) -> str:
         return "get_method"
 
-    @fastapi_endpoint("post", path="path_from_path")
+    @lt.fastapi_endpoint("post", path="path_from_path")
     def post_method(self, body: PostBodyModel) -> str:
         return f"post_method {body.a} {body.b}"
 
 
 def test_endpoints():
-    server = ThingServer()
-    server.add_thing(TestThing(), "/thing")
+    """Check endpoints may be added to the app and work as expected."""
+    server = lt.ThingServer()
+    thing = MyThing()
+    server.add_thing(thing, "/thing")
     with TestClient(server.app) as client:
+        # Check the function works when used directly
+        assert thing.path_from_name() == "path_from_name"
+        # Check it works identically over HTTP. The path is
+        # generated from the name of the function.
         r = client.get("/thing/path_from_name")
         r.raise_for_status()
         assert r.json() == "path_from_name"
 
+        # get_method has an explicit path - check it can be
+        # used both directly and via that path.
+        assert thing.get_method() == "get_method"
         r = client.get("/thing/path_from_path")
         r.raise_for_status()
         assert r.json() == "get_method"
 
+        # post_method uses the same path, for a different
+        # function
+        assert thing.post_method(PostBodyModel(a=1, b=2)) == "post_method 1 2"
         r = client.post("/thing/path_from_path", json={"a": 1, "b": 2})
         r.raise_for_status()
         assert r.json() == "post_method 1 2"
+
+
+def test_endpoint_notconnected(mocker):
+    """Check for the correct error if we add endpoints prematurely.
+
+    We should get this error if we call ``add_to_fastapi`` on an endpoint
+    where the `.Thing` does not have a valid ``path`` attribute.
+    """
+    thing = MyThing()
+
+    with pytest.raises(lt.exceptions.NotConnectedToServerError):
+        MyThing.get_method.add_to_fastapi(mocker.Mock(), thing)