updated spectral tests

mne_connectivity/spectral/tests/test_spectral.py

@@ -1286,7 +1286,7 @@ def test_save(tmp_path):
 def test_multivar_save_load(tmp_path):
     """Test saving and loading results of multivariate connectivity."""
     rng = np.random.RandomState(0)
-    n_epochs, n_chs, n_times, sfreq, f = 10, 4, 2000, 1000., 20.
+    n_epochs, n_chs, n_times, sfreq, f = 5, 4, 2000, 1000., 20.
     data = rng.randn(n_epochs, n_chs, n_times)
     sig = np.sin(2 * np.pi * f * np.arange(1000) / sfreq) * np.hanning(1000)
     data[:, :, 500:1500] += sig
@@ -1313,3 +1313,48 @@ def test_multivar_save_load(tmp_path):
             a = repr(this_con).split('~')[0]
             b = repr(read_con).split('~')[0]
             assert a == b
+
+
+def test_spectral_connectivity_indices_maintained(tmp_path):
+    """Test that indices values and type is maintained after saving.
+
+    If `indices` is None, `indices` in the returned connectivity object should
+    be None, otherwise, `indices` should be a tuple. The type of `indices` and
+    its values should be retained after saving and reloading.
+    """
+    rng = np.random.RandomState(0)
+    n_epochs, n_chs, n_times, sfreq, f = 5, 4, 2000, 1000., 20.
+    data = rng.randn(n_epochs, n_chs, n_times)
+    sig = np.sin(2 * np.pi * f * np.arange(1000) / sfreq) * np.hanning(1000)
+    data[:, :, 500:1500] += sig
+    info = create_info(n_chs, sfreq, 'eeg')
+    tmin = -1
+    epochs = EpochsArray(data, info, tmin=tmin)
+    freqs = np.arange(10, 31)
+    tmp_file = os.path.join(tmp_path, 'foo_mvc.nc')
+
+    bivar_indices = (np.array([0, 1]), np.array([2, 3]))
+    multivar_indices = (np.array([[0, 1]]), np.array([[2, 3]]))
+    indices = [None, bivar_indices, None, multivar_indices]
+    methods = ['coh', 'coh', 'mic', 'mic']
+
+    for this_indices, this_method in zip(indices, methods):
+        con_epochs = spectral_connectivity_epochs(
+            epochs, method=this_method, indices=this_indices, sfreq=sfreq,
+            fmin=10, fmax=30)
+        con_time = spectral_connectivity_time(
+            epochs, freqs, method=this_method, indices=this_indices,
+            sfreq=sfreq)
+
+        for con in [con_epochs, con_time]:
+            con.save(tmp_file)
+            read_con = read_connectivity(tmp_file)
+            if this_indices is not None:
+                # check indices of same type (tuples)
+                assert (isinstance(con.indices, tuple) and
+                        isinstance(read_con.indices, tuple))
+                # check indices have same values
+                assert np.all(np.array(con.indices) ==
+                              np.array(read_con.indices))
+            else:
+                assert con.indices is None and read_con.indices is None