updating tests to reproduce a previous problem

mne/channels/channels.py

@@ -560,22 +560,24 @@ def inst_has(attr):
         elif isinstance(self, Evoked):
             self.data = self.data.take(idx, axis=0)
 
-    def add_channels(self, add_list, force_update_info=False, copy=None):
+    def add_channels(self, add_list, copy=None, force_update_info=False):
         """Append new channels to the instance.
 
         Parameters
         ----------
         add_list : list
             A list of objects to append to self. Must contain all the same
             type as the current object
-        force_update_info : bool
-            If True, force the info for objects to be appended to match the
-            values in `self`. This should generally only be used when adding
-            stim channels for which important metadata won't be overwritten.
         copy : bool
             This parameter has been deprecated and will be removed in 0.13.
             Use inst.copy() instead.
             Whether to return a new instance or modify in place.
+        force_update_info : bool
+            If True, force the info for objects to be appended to match the
+            values in `self`. This should generally only be used when adding
+            stim channels for which important metadata won't be overwritten.
+
+            .. versionadded:: 0.12
 
         Returns
         -------

mne/io/fiff/tests/test_raw_fiff.py

@@ -1051,20 +1051,22 @@ def test_add_channels():
     )
     raw_new = raw_meg.copy().add_channels([raw_eeg])
 
-    # Testing force updates
-    raw_eeg_conf = raw_eeg.copy()
-    raw_eeg_conf.info['sfreq'] = 1.
-    assert_raises(RuntimeError, raw_meg.copy().add_channels, [raw_eeg_conf])
-    raw_new = raw_meg.copy().add_channels([raw_eeg_conf],
-                                          force_update_info=True)
-    assert_true(raw_eeg_conf.info['sfreq'] == 1.)
-    assert_true(raw_new.info['sfreq'] == raw_meg.info['sfreq'])
-
     assert_true(ch in raw_new.ch_names for ch in raw.ch_names)
     assert_array_equal(raw_new[:, :][0], raw_eeg_meg[:, :][0])
     assert_array_equal(raw_new[:, :][1], raw[:, :][1])
     assert_true(all(ch not in raw_new.ch_names for ch in raw_stim.ch_names))
 
+    # Testing force updates
+    raw_arr_info = create_info(['1', '2'], raw_meg.info['sfreq'], 'eeg')
+    orig_head_t = raw_arr_info['dev_head_t']
+    raw_arr = np.random.randn(2, raw_eeg.n_times)
+    raw_arr = RawArray(raw_arr, raw_arr_info)
+    # This should error because of conflicts in Info
+    assert_raises(ValueError, raw_meg.copy().add_channels, [raw_arr])
+    raw_meg.copy().add_channels([raw_arr], force_update_info=True)
+    # Make sure that values didn't get overwritten
+    assert_true(raw_arr.info['dev_head_t'] is orig_head_t)
+
     # Now test errors
     raw_badsf = raw_eeg.copy()
     raw_badsf.info['sfreq'] = 3.1415927

mne/io/meas_info.py

@@ -1504,9 +1504,10 @@ def _force_update_info(info_base, info_target):
     exclude_keys = ['chs', 'ch_names', 'nchan']
     info_target = np.atleast_1d(info_target).ravel()
     all_infos = np.hstack([info_base, info_target])
-    msg = 'Inputs must be of type Info. Found type {0}'
-    if not all([isinstance(ii, Info) for ii in all_infos]):
-        raise ValueError(msg.format(type(ii)))
+    for ii in all_infos:
+        if not isinstance(ii, Info):
+            raise ValueError('Inputs must be of type Info. '
+                             'Found type %s' % type(ii))
     for key, val in info_base.items():
         if key in exclude_keys:
             continue

mne/io/tests/test_meas_info.py

@@ -269,6 +269,7 @@ def test_merge_info():
 
     # Testing for force updates before merging
     info_c = create_info(ch_names=['g', 'h', 'i'], sfreq=500., ch_types=None)
+    # This will break because sfreq is not equal
     assert_raises(RuntimeError, _merge_info, [info_a, info_c])
     _force_update_info(info_a, info_c)
     assert_true(info_c['sfreq'] == info_a['sfreq'])