Fix typing in MJPG stream and fix system test

src/dodal/devices/areadetector/plugins/MJPG.py

@@ -1,6 +1,7 @@
 import os
 import threading
 from abc import ABC, abstractmethod
+from io import BytesIO
 from pathlib import Path
 
 import requests
@@ -70,7 +71,7 @@ def get_snapshot():
             try:
                 response = requests.get(url_str, stream=True)
                 response.raise_for_status()
-                with Image.open(response.raw) as image:
+                with Image.open(BytesIO(response.content)) as image:
                     self.post_processing(image)
                     st.set_finished()
             except requests.HTTPError as e:

tests/devices/system_tests/test_oav_system.py

@@ -27,11 +27,12 @@ def take_snapshot_with_grid(oav: OAV, snapshot_filename, snapshot_directory):
     yield from bps.trigger(oav.grid_snapshot, wait=True)
 
 
+# We need to find a better way of integrating this, see https://github.com/DiamondLightSource/mx-bluesky/issues/183
 @pytest.mark.skip(reason="Don't want to actually take snapshots during testing.")
 def test_grid_overlay(RE: RunEngine):
     beamline = "BL03I"
     oav_params = OAVConfigParams(ZOOM_LEVELS_XML, DISPLAY_CONFIGURATION)
-    oav = OAV(name="oav", prefix=f"{beamline}-DI-OAV-01", params=oav_params)
+    oav = OAV(name="oav", prefix=f"{beamline}", params=oav_params)
     snapshot_filename = "snapshot"
     snapshot_directory = "."
     RE(take_snapshot_with_grid(oav, snapshot_filename, snapshot_directory))

tests/devices/unit_tests/areadetector/plugins/test_MJPG.py

@@ -17,6 +17,7 @@ def test_given_snapshot_triggered_then_crosshair_drawn(
     patch_requests, patch_image_draw, patch_os, patch_image
 ):
     patch_line = MagicMock()
+    patch_requests.get.return_value.content = b""
     params = OAVConfigParams(ZOOM_LEVELS_XML, DISPLAY_CONFIGURATION)
     params.update_on_zoom(1.0, 100, 100)
 

tests/devices/unit_tests/test_oav.py

@@ -50,6 +50,15 @@ def fake_oav() -> OAV:
     return fake_oav
 
 
+@pytest.fixture
+def mock_get_with_valid_response():
+    patcher = patch("requests.get")
+    mock_get = patcher.start()
+    mock_get.return_value.content = b""
+    yield mock_get
+    patcher.stop()
+
+
 @patch("requests.get")
 def test_snapshot_trigger_handles_request_with_bad_status_code_correctly(
     mock_get, fake_oav: OAV
@@ -63,22 +72,20 @@ def test_snapshot_trigger_handles_request_with_bad_status_code_correctly(
         st.wait()
 
 
-@patch("requests.get")
 @patch("dodal.devices.areadetector.plugins.MJPG.Image")
 @patch("dodal.devices.areadetector.plugins.MJPG.os", new=MagicMock())
 def test_snapshot_trigger_loads_correct_url(
-    mock_image: MagicMock, mock_get: MagicMock, fake_oav: OAV
+    mock_image: MagicMock, mock_get_with_valid_response: MagicMock, fake_oav: OAV
 ):
     st = fake_oav.grid_snapshot.trigger()
     st.wait()
-    mock_get.assert_called_once_with("http://test.url", stream=True)
+    mock_get_with_valid_response.assert_called_once_with("http://test.url", stream=True)
 
 
-@patch("requests.get")
 @patch("dodal.devices.areadetector.plugins.MJPG.Image.open")
 @patch("dodal.devices.areadetector.plugins.MJPG.os", new=MagicMock())
 def test_snapshot_trigger_saves_to_correct_file(
-    mock_open: MagicMock, mock_get, fake_oav
+    mock_open: MagicMock, mock_get_with_valid_response, fake_oav
 ):
     image = Image.open("test")
     mock_open.return_value.__enter__.return_value = image
@@ -93,23 +100,21 @@ def test_snapshot_trigger_saves_to_correct_file(
         assert calls_to_save == expected_calls_to_save
 
 
-@patch("requests.get")
 @patch("dodal.devices.areadetector.plugins.MJPG.Image.open")
 @patch("dodal.devices.areadetector.plugins.MJPG.os")
 def test_given_directory_not_existing_when_snapshot_triggered_then_directory_created(
-    mock_os, mock_open: MagicMock, mock_get, fake_oav
+    mock_os, mock_open: MagicMock, mock_get_with_valid_response, fake_oav
 ):
     mock_os.path.isdir.return_value = False
     st = fake_oav.grid_snapshot.trigger()
     st.wait()
     mock_os.mkdir.assert_called_once_with("test directory")
 
 
-@patch("requests.get")
 @patch("dodal.devices.areadetector.plugins.MJPG.Image.open")
 @patch("dodal.devices.areadetector.plugins.MJPG.os", new=MagicMock())
 def test_snapshot_trigger_applies_current_microns_per_pixel_to_snapshot(
-    mock_open: MagicMock, mock_get, fake_oav
+    mock_open: MagicMock, mock_get_with_valid_response, fake_oav
 ):
     image = Image.open("test")  # type: ignore
     mock_open.return_value.__enter__.return_value = image
@@ -123,7 +128,6 @@ def test_snapshot_trigger_applies_current_microns_per_pixel_to_snapshot(
         assert fake_oav.grid_snapshot.microns_per_pixel_y.get() == expected_mpp_y
 
 
-@patch("requests.get")
 @patch("dodal.devices.areadetector.plugins.MJPG.Image.open")
 @patch("dodal.devices.oav.grid_overlay.add_grid_overlay_to_image")
 @patch("dodal.devices.oav.grid_overlay.add_grid_border_overlay_to_image")
@@ -132,7 +136,7 @@ def test_correct_grid_drawn_on_image(
     mock_border_overlay: MagicMock,
     mock_grid_overlay: MagicMock,
     mock_open: MagicMock,
-    mock_get: MagicMock,
+    mock_get_with_valid_response: MagicMock,
     fake_oav: OAV,
 ):
     st = fake_oav.grid_snapshot.trigger()