Adding even more ROM tests

src/openflexure_microscope_server/things/stage_measure.py

@@ -43,6 +43,7 @@ MEDIUM_STEP = 50
 BIG_STEP = 200
 
 PARASITIC_MOTION_TOL = 0.1
+DETECT_MOTION_TOL = 0.65
 
 
 class RomDataTracker:
@@ -196,7 +197,7 @@ class RangeofMotionThing(lt.Thing):
         }
 
     def _set_stream_resolution(self, cam: CamDep) -> None:
-        """Set the self._stream_reolution attribute by reading camera.
+        """Set the self._stream_resolution attribute by reading camera.
 
         :param cam: The camera dependency.
         """
@@ -288,7 +289,7 @@ class RangeofMotionThing(lt.Thing):
         """
         if self._stream_resolution is None:
             raise RuntimeError(
-                "Stream resolution mut be set before generating movement in coords"
+                "Stream resolution must be set before generating movement in coords"
             )
 
         img_index = 0 if axis == "x" else 1
@@ -372,13 +373,11 @@ class RangeofMotionThing(lt.Thing):
     ) -> bool:
         """Carry out 3 small moves in a given direction and axis.
 
-        Each position after the first is correlated with the previous position
-        to check the stage has moved as far as it should. If the correlation is
-        less than expected, 3 attempts are made to refocus the image to ensure that
-        image quality is not causing the correlation to be unsuccessful. If the correlation
-        is still too low then the edge is found.
-
-        Delta is updated and tracked after each move.
+        An image is taken before and after each move to check has moved as far as it
+        should. If the offset (calculated by cross correlation) is less than expected,
+        3 attempts are made to refocus the image to ensure that image quality is not
+        causing the offset to mistakenly be reported as too low be unsuccessful. If the
+        calculated offset is still too low then the edge is found.
 
         :param axis: The axis which is being measured. This must be 'x' or 'y'.
         :param direction: The direction the stage moves.
@@ -387,7 +386,7 @@ class RangeofMotionThing(lt.Thing):
         movement = self._movement_in_img_coords(
             fov_perc=SMALL_STEP, axis=axis, direction=direction
         )
-        abs_min_offset = abs(movement[axis] * 0.65)
+        abs_min_offset = abs(movement[axis] * DETECT_MOTION_TOL)
 
         for _loop in range(3):
             offset = self._move_and_measure(
@@ -472,8 +471,7 @@ class RangeofMotionThing(lt.Thing):
             if ``abs_min_offset`` is also set
         :param abs_min_offset: The absolute minimum (on-axis) offset, under which the
             autofocus is repeated.
-        :return: All required data for the next move. This includes the updated delta
-            value and offset.
+        :return: The calculated offset from cross correlation.
         """
         # Take image before move
         before_img = rom_deps.cam.grab_as_array()

tests/test_stage_measure.py

@@ -219,3 +219,53 @@ def test_move_back_until_motion_detected(rom_thing, mock_rom_deps, mocker):
     for i, call_args in enumerate(mock_move_n_meas.call_args_list):
         call_args.kwargs["movement"] = {"x": -(2**i), "y": 0}
         call_args.kwargs["perform_autofocus"] = False
+
+
+@pytest.mark.parametrize(
+    ("good_moves", "expected_to_detect_motion", "offset_calls"),
+    [
+        ([0, 1, 2], True, 3),  # First 3 pass all good
+        ([1, 2, 3], True, 4),  # First is bad, will refocus, still complete
+        ([2, 3, 4], True, 5),  # First 2 are bad, will refocus twice, still complete
+        ([3, 4, 5], True, 6),  # First 3 are bad, will refocus 3 times, still complete
+        ([4, 5, 6], False, 4),  # First 4 are bad, fails
+        # Check second and 3rd measurement can fail after first fails 3 times
+        ([3, 5, 7], True, 8),
+        ([3, 6, 9], True, 10),
+        ([3, 7, 11], True, 12),
+        # But they can't fail 4 times
+        ([3, 8, 9], False, 8),
+        ([3, 7, 12], False, 12),
+    ],
+)
+def test_stage_still_moves(
+    good_moves,
+    expected_to_detect_motion,
+    offset_calls,
+    rom_thing,
+    mock_rom_deps,
+    mocker,
+):
+    """Test _stage_still_moves correctly detects stage movement."""
+    rom_thing._stream_resolution = [800, 600]
+    min_offset = 800 * stage_measure.SMALL_STEP / 100 * stage_measure.DETECT_MOTION_TOL
+
+    def gen_offsets(*_args, **_kwargs):
+        """Generate offset dictionaries with small moves unless count matches ``good_moves``."""
+        i = 0
+        while True:
+            x = min_offset * 1.2 if i in good_moves else 0.1
+            yield {"x": x, "y": 0}
+            i += 1
+
+    mock_offset_from = mocker.patch.object(
+        rom_thing, "_offset_from", side_effect=gen_offsets()
+    )
+
+    still_moves = rom_thing._stage_still_moves(
+        axis="x",
+        direction=1,
+        rom_deps=mock_rom_deps,
+    )
+    assert still_moves is expected_to_detect_motion
+    assert mock_offset_from.call_count == offset_calls