TST: Add regression coverage for OPM topomap grouping via plot_joint() and ICA (#13842)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: PragnyaKhandelwal

doc/changes/dev/13842.other.rst

@@ -0,0 +1 @@
+Added regression coverage for colocated triaxial OPM topomap handling in ``plot_joint()`` and ``ICA.plot_components()``, by `Pragnya Khandelwal`_.

mne/conftest.py

@@ -27,12 +27,13 @@
 
 # ruff: noqa: E402
 import mne
-from mne import Epochs, pick_types, read_events
+from mne import Epochs, create_info, make_fixed_length_epochs, pick_types, read_events
+from mne._fiff.constants import FIFF
 from mne.channels import read_layout
 from mne.coreg import create_default_subject
 from mne.datasets import testing
 from mne.fixes import _compare_version, has_numba
-from mne.io import read_raw_ctf, read_raw_fif, read_raw_nirx, read_raw_snirf
+from mne.io import RawArray, read_raw_ctf, read_raw_fif, read_raw_nirx, read_raw_snirf
 from mne.stats import cluster_level
 from mne.utils import (
     Bunch,
@@ -546,6 +547,47 @@ def _bias_params(evoked, noise_cov, fwd):
     return evoked, fwd, noise_cov, data_cov, want
 
 
+@pytest.fixture
+def triaxial_raw():
+    """Create a small triaxial OPM raw for regression tests."""
+    ch_names = ["OPM001", "OPM002", "OPM003", "OPM004", "OPM005", "OPM006"]
+    info = create_info(ch_names, 1000.0, ch_types="mag")
+    positions = np.array(
+        [
+            [0.03, 0.00, 0.05],
+            [0.03, 0.00, 0.05],
+            [0.03, 0.00, 0.05],
+            [-0.03, 0.00, 0.05],
+            [-0.03, 0.00, 0.05],
+            [-0.03, 0.00, 0.05],
+        ]
+    )
+    orientations = np.array(
+        [
+            [0.5145, 0.0000, 0.8575],
+            [0.0000, 1.0000, 0.0000],
+            [0.0000, 0.0000, 1.0000],
+            [-0.5145, 0.0000, 0.8575],
+            [0.0000, 1.0000, 0.0000],
+            [0.0000, 0.0000, 1.0000],
+        ]
+    )
+    with info._unlock():
+        for idx, ch in enumerate(info["chs"]):
+            ch["coil_type"] = FIFF.FIFFV_COIL_FIELDLINE_OPM_MAG_GEN1
+            ch["loc"][:3] = positions[idx]
+            ch["loc"][9:12] = orientations[idx]
+    rng = np.random.default_rng(0)
+    data = rng.standard_normal((len(ch_names), 2000))
+    return RawArray(data, info, verbose="error")
+
+
+@pytest.fixture
+def triaxial_evoked(triaxial_raw):
+    """Create a small triaxial OPM evoked for regression tests."""
+    return make_fixed_length_epochs(triaxial_raw).average()
+
+
 @pytest.fixture
 def garbage_collect():
     """Garbage collect on exit."""

mne/viz/tests/test_ica.py

@@ -574,3 +574,15 @@ def test_plot_components_opm():
     ica.fit(RawArray(evoked.data, evoked.info), picks="mag", verbose="error")
     fig = ica.plot_components()
     assert len(fig.axes) == 10
+
+
+@pytest.mark.slowtest
+@pytest.mark.filterwarnings(
+    "ignore:FastICA did not converge.*:sklearn.exceptions.ConvergenceWarning"
+)
+def test_plot_components_opm_triaxial(triaxial_raw):
+    """Test OPM component topomaps with colocated triaxial channels."""
+    ica = ICA(max_iter=1, random_state=0, n_components=3)
+    ica.fit(triaxial_raw, picks="mag", verbose="error")
+    fig = ica.plot_components()
+    assert len(fig.axes) == 3

mne/viz/tests/test_topo.py

@@ -10,7 +10,12 @@
 import numpy as np
 import pytest
 
-from mne import Epochs, compute_proj_evoked, read_cov, read_events
+from mne import (
+    Epochs,
+    compute_proj_evoked,
+    read_cov,
+    read_events,
+)
 from mne.channels import read_layout
 from mne.io import read_raw_fif
 from mne.time_frequency.tfr import AverageTFRArray
@@ -116,7 +121,6 @@ def return_inds(d):  # to test function kwarg to zorder arg of evoked.plot
     evoked.plot_joint(
         ts_args=dict(proj="reconstruct"), topomap_args=dict(proj="reconstruct")
     )
-    plt.close("all")
 
     # test sEEG (gh:8733)
     evoked.del_proj().pick("mag")  # avoid overlapping positions error
@@ -132,6 +136,18 @@ def return_inds(d):  # to test function kwarg to zorder arg of evoked.plot
     plt.close("all")
 
 
+def test_plot_joint_opm_triaxial(triaxial_evoked):
+    """Test joint plot with triaxial colocated OPM channels."""
+    fig = triaxial_evoked.plot_joint(
+        times=[0.0],
+        picks="mag",
+        show=False,
+        ts_args=dict(time_unit="s"),
+        topomap_args=dict(time_unit="s", contours=0, res=8, sensors=False),
+    )
+    assert len(fig.axes) >= 2
+
+
 def test_plot_topo():
     """Test plotting of ERP topography."""
     # Show topography