Add a first unit test

This checks that the server can start
and perform an autofocus.
Autofocus in turn will test the camera and stage dependencies.

tests/test_dummy_server.py

@@ -0,0 +1,22 @@
+import tempfile
+
+from fastapi import Depends, FastAPI
+from fastapi.testclient import TestClient
+
+from labthings_fastapi.client import ThingClient
+
+from openflexure_microscope_server.server import ThingServer
+from openflexure_microscope_server.things.camera.simulation import SimulatedCamera
+from openflexure_microscope_server.things.stage.dummy import DummyStage
+from openflexure_microscope_server.things.autofocus import AutofocusThing
+
+temp_folder = tempfile.TemporaryDirectory()
+server = ThingServer(temp_folder.name)
+server.add_thing(SimulatedCamera(), "/camera/")
+server.add_thing(DummyStage(), "/stage/")
+server.add_thing(AutofocusThing(), "/autofocus/")
+
+def test_autofocus():
+    with TestClient(server.app) as client:
+        autofocus = ThingClient.from_url("/autofocus/", client)
+        _ = autofocus.fast_autofocus()