Add tests

Author: SimonHeybrock

src/ess/dream/__init__.py

@@ -6,6 +6,7 @@
 """
 import importlib.metadata
 
+from . import data
 from .io import load_nexus
 
 try:
@@ -16,5 +17,6 @@
 del importlib
 
 __all__ = [
+    "data",
     "load_nexus",
 ]

src/ess/dream/data.py

@@ -0,0 +1,34 @@
+# SPDX-License-Identifier: BSD-3-Clause
+# Copyright (c) 2023 Scipp contributors (https://github.com/scipp)
+_version = '1'
+
+__all__ = ['get_path']
+
+
+def _make_pooch():
+    import pooch
+
+    return pooch.create(
+        path=pooch.os_cache('ess/powgen'),
+        env='ESS_DATA_DIR',
+        base_url='https://public.esss.dk/groups/scipp/ess/dream/{version}/',
+        version=_version,
+        registry={
+            'DREAM_nexus_sorted-2023-12-07.nxs': 'md5:22824e14f6eb950d24a720b2a0e2cb66',
+        },
+    )
+
+
+_pooch = _make_pooch()
+
+
+def get_path(name: str, unzip: bool = False) -> str:
+    """
+    Return the path to a data file bundled with ess.dream.
+
+    This function only works with example data and cannot handle
+    paths to custom files.
+    """
+    import pooch
+
+    return _pooch.fetch(name, processor=pooch.Unzip() if unzip else None)

src/ess/dream/io.py

@@ -10,6 +10,7 @@
 
 def load_nexus(
     path: Union[str, os.PathLike],
+    *,
     load_pixel_shape: bool = False,
     entry: str = 'entry',
     fold_detectors: bool = True,
@@ -24,10 +25,10 @@ def load_nexus(
 
     - Mounting-unit, cassette, and counter roughly correspond to the azimuthal angle
       in the mantle detector. However, counter is reversed in the current files. This
-      may also be the case in the other detectors
+      may also be the case in the other detectors.
     - The endcap detectors have a irregular structure that cannot be fully folded.
-      This is not a problem but not again that the counter may be reversed. It is
-      current not clear if this is a bug in the file.
+      This is not a problem but note again that the counter may be reversed. It is
+      currently not clear if this is a bug in the file.
     - The high-resolution detector has a very odd numbering scheme. The SANS detector
       is using the same, but is not populated in the current files. The scheme
       attempts to follows some sort of physical ordering in space (x,y,z), but it

tests/dream/io_test.py

@@ -0,0 +1,77 @@
+# SPDX-License-Identifier: BSD-3-Clause
+# Copyright (c) 2023 Scipp contributors (https://github.com/scipp)
+import pytest
+
+from ess import dream
+
+
+@pytest.fixture
+def filename():
+    return dream.data.get_path('DREAM_nexus_sorted-2023-12-07.nxs')
+
+
+@pytest.mark.filterwarnings("ignore:Failed to load /entry/instrument/monitor_bunker")
+@pytest.mark.filterwarnings("ignore:Failed to load /entry/instrument/monitor_cave")
+@pytest.mark.filterwarnings("ignore:Failed to load /entry/instrument/polarizer/rate")
+@pytest.mark.filterwarnings("ignore:Failed to load /entry/instrument/sans_detector")
+def test_load_nexus_loads_file(filename):
+    dg = dream.load_nexus(filename)
+    assert 'instrument' in dg
+    instr = dg['instrument']
+    for name in (
+        'mantle',
+        'endcap_backward',
+        'endcap_forward',
+        'high_resolution',
+        'sans',
+    ):
+        assert f'{name}_detector' in instr
+        det = instr[f'{name}_detector']
+        assert 'pixel_shape' not in det
+
+
+def test_load_nexus_fails_if_entry_not_found(filename):
+    with pytest.raises(KeyError):
+        dream.load_nexus(filename, entry='foo')
+
+
+@pytest.mark.filterwarnings("ignore:Failed to load /entry/instrument/monitor_bunker")
+@pytest.mark.filterwarnings("ignore:Failed to load /entry/instrument/monitor_cave")
+@pytest.mark.filterwarnings("ignore:Failed to load /entry/instrument/polarizer/rate")
+@pytest.mark.filterwarnings("ignore:Failed to load /entry/instrument/sans_detector")
+def test_load_nexus_folds_detectors_by_default(filename):
+    dg = dream.load_nexus(filename)
+    instr = dg['instrument']
+    # sans_detector is not populated in the current files
+    for name in ('mantle', 'endcap_backward', 'endcap_forward', 'high_resolution'):
+        det = instr[f'{name}_detector']
+        # There may be other dims, but some are irregular and this may be subject to
+        # change
+        assert 'strip' in det.dims
+
+
+@pytest.mark.filterwarnings("ignore:Failed to load /entry/instrument/monitor_bunker")
+@pytest.mark.filterwarnings("ignore:Failed to load /entry/instrument/monitor_cave")
+@pytest.mark.filterwarnings("ignore:Failed to load /entry/instrument/polarizer/rate")
+@pytest.mark.filterwarnings("ignore:Failed to load /entry/instrument/sans_detector")
+def test_load_nexus_with_disabled_fold(filename):
+    dg = dream.load_nexus(filename, fold_detectors=False)
+    instr = dg['instrument']
+    for name in ('mantle', 'endcap_backward', 'endcap_forward', 'high_resolution'):
+        det = instr[f'{name}_detector']
+        assert det.dims == ('detector_number',)
+
+
+@pytest.mark.filterwarnings("ignore:Failed to load /entry/instrument/monitor_bunker")
+@pytest.mark.filterwarnings("ignore:Failed to load /entry/instrument/monitor_cave")
+@pytest.mark.filterwarnings("ignore:Failed to load /entry/instrument/polarizer/rate")
+@pytest.mark.filterwarnings("ignore:Failed to load /entry/instrument/sans_detector")
+def test_load_nexus_with_pixel_shape(filename):
+    dg = dream.load_nexus(filename, load_pixel_shape=True)
+    assert 'instrument' in dg
+    instr = dg['instrument']
+    # sans_detector is not populated in the current files
+    for name in ('mantle', 'endcap_backward', 'endcap_forward', 'high_resolution'):
+        assert f'{name}_detector' in instr
+        det = instr[f'{name}_detector']
+        assert 'pixel_shape' in det