Update picamera tests to use new test environment

hardware-specific-tests/picamera2/cam_test_utils.py

@@ -0,0 +1,37 @@
+"""Utilities to help with testing the camera."""
+
+from contextlib import contextmanager
+from typing import Optional
+
+from openflexure_microscope_server.things.camera.picamera import StreamingPiCamera2
+
+from ..tests.utilities.lt_test_utils import LabThingsTestEnv
+
+
+@contextmanager
+def camera_test_env(settings_folder: Optional[str] = None):
+    """Yield a test environment with a server that contains just the camera.
+
+    This is a context manager, not a pytest fixture, as it needs to be created
+    multiple times in some tests.
+
+    :param settings_folder: The settings folder for the camera, if none is supplied, new
+        temporary directory will be used as the settings folder.
+    """
+    thing_conf = {"camera": StreamingPiCamera2}
+    with LabThingsTestEnv(things=thing_conf, settings_folder=settings_folder) as env:
+        yield env
+
+
+@contextmanager
+def camera_test_client(settings_folder: Optional[str] = None):
+    """Yield a camera ThingClient on a camera server.
+
+    This is a context manager, not a pytest fixture, as it needs to be created
+    multiple times in some tests.
+
+    :param settings_folder: The settings folder for the camera, if none is supplied, new
+        temporary directory will be used as the settings folder.
+    """
+    with camera_test_env(settings_folder=settings_folder) as env:
+        return env.get_thing_client("camera")