1756 nexus generates wrong omega multipin

src/mx_bluesky/common/parameters/rotation.py

@@ -120,7 +120,8 @@ def scan_points(self) -> AxesPoints:
             start=self.omega_start_deg,
             stop=(
                 self.omega_start_deg
-                + (self.scan_width_deg - self.rotation_increment_deg)
+                + self.rotation_direction.multiplier
+                * (self.scan_width_deg - self.rotation_increment_deg)
             ),
             num=self.num_images,
         )

tests/system_tests/hyperion/external_interaction/test_nexgen.py

@@ -7,6 +7,7 @@
 
 import bluesky.preprocessors as bpp
 import pytest
+from dodal.devices.zebra.zebra import RotationDirection
 
 from mx_bluesky.common.experiment_plans.inner_plans.read_hardware import (
     standard_read_hardware_during_collection,
@@ -28,7 +29,7 @@
 
 
 @pytest.fixture
-def test_params(tmp_path, config_client):
+def test_params(tmp_path, config_client, request):
     param_dict = raw_params_from_file(
         "tests/test_data/parameter_json_files/good_test_rotation_scan_parameters.json",
         tmp_path,
@@ -41,23 +42,36 @@ def test_params(tmp_path, config_client):
     params.y_start_um = 0
     params.z_start_um = 0
     params.exposure_time_s = 0.004
+    params.rotation_direction = request.param
+    params.omega_start_deg = (
+        0 if params.rotation_direction == RotationDirection.POSITIVE else 360
+    )
     return params
 
 
 @pytest.mark.parametrize(
-    "test_data_directory, prefix, reference_file",
+    "test_data_directory, prefix, reference_file, test_params",
     [
         (
             "tests/test_data/nexus_files/rotation",
             "ins_8_5",
             "ins_8_5_expected_output.txt",
+            RotationDirection.POSITIVE,
+        ),
+        (
+            "tests/test_data/nexus_files/rotation",
+            "ins_8_5",
+            "ins_8_5_expected_output.txt",
+            RotationDirection.NEGATIVE,
         ),
         (
             "tests/test_data/nexus_files/rotation_unicode_metafile",
             "ins_8_5",
             "ins_8_5_expected_output.txt",
+            RotationDirection.POSITIVE,
         ),
     ],
+    indirect=["test_params"],
 )
 @patch(
     "mx_bluesky.common.external_interaction.nexus.nexus_utils.time.time",

tests/test_data/parameter_json_files/good_test_rotation_scan_parameters.json

@@ -5,10 +5,7 @@
     "detector_distance_mm": 100.0,
     "demand_energy_ev": 100,
     "exposure_time_s": 0.1,
-    "omega_starts_deg": [
-        0,
-        90
-    ],
+    "omega_start_deg": 0.0,
     "file_name": "file_name",
     "scan_width_deg": 180.0,
     "rotation_axis": "omega",

tests/unit_tests/common/parameters/test_rotation.py

@@ -0,0 +1,37 @@
+from pathlib import Path
+
+import numpy as np
+import pytest
+
+from mx_bluesky.common.parameters.rotation import SingleRotationScan
+
+from ...conftest import raw_params_from_file
+
+
+@pytest.mark.parametrize(
+    "omega_start_deg, rotation_direction, rotation_increment_deg, scan_width_deg, expected_omegas",
+    [
+        [0, "Positive", 0.25, 0.5, [0.0, 0.25]],
+        [0, "Negative", 0.25, 0.5, [0.0, -0.25]],
+    ],
+)
+def test_single_rotation_scan_scan_points(
+    omega_start_deg: float,
+    rotation_direction: str,
+    rotation_increment_deg: float,
+    scan_width_deg: float,
+    expected_omegas: list[float],
+    tmp_path: Path,
+):
+    params = raw_params_from_file(
+        "tests/test_data/parameter_json_files/good_test_rotation_scan_parameters.json",
+        tmp_path,
+    )
+    params |= {
+        "omega_start_deg": omega_start_deg,
+        "rotation_direction": rotation_direction,
+        "rotation_increment_deg": rotation_increment_deg,
+        "scan_width_deg": scan_width_deg,
+    }
+    rotation_scan = SingleRotationScan(**params)
+    assert np.all(rotation_scan.scan_points["omega"] == np.array(expected_omegas))