def test_drop_channels_mixin():
    evoked = read_evokeds(fname, condition=0, proj=True)
    drop_ch = evoked.ch_names[:3]
    ch_names = evoked.ch_names[3:]

    ch_names_orig = evoked.ch_names
    dummy = evoked.copy().drop_channels(drop_ch)
    assert_equal(ch_names, dummy.ch_names)
    assert_equal(ch_names_orig, evoked.ch_names)
    assert_equal(len(ch_names_orig), len(evoked.data))

    evoked.drop_channels(drop_ch)
    assert_equal(ch_names, evoked.ch_names)
    assert_equal(len(ch_names), len(evoked.data))
Test channels-dropping functionality
dataset/ETHPy150Open mne-tools/mne-python/mne/tests/test_evoked.py/test_drop_channels_mixin