'Verify append_col() with header correctly detects mismatch when
headers exist but there is no existing row data'

def test_add_column_with_header_and_headers_only_exist(self):

    data.headers = ['first_name']
    new_col = 'allen'
    def append_col_callable():
        data.append_col(new_col, header='middle_name')
    self.assertRaises(tablib.InvalidDimensions, append_col_callable)
