Unittest takes 1 positional argument but 2 were given

Question

I'm trying to unittest my code however I always obtain the following error:

ERROR: test_FlipVertically1D_empty_array (main.TestMarginSampling)

Traceback (most recent call last): File "C:\Users\s\anaconda3\lib\unittest\mock.py", line 1337, in patched return func(*newargs, **newkeywargs) TypeError: test_FlipVertically1D_empty_array() takes 1 positional argument but 2 were given

Here is the code for my class:

class FlipVertically1D:   
    @staticmethod 
    def calc(data: np.ndarray) -> np.ndarray:
        return - data

and here the code for my unittest:

import pandas as pd
import numpy as np
import unittest
from unittest.mock import patch, MagicMock

from ddt import ddt, data, file_data, idata, unpack


from augmentation.augment import FlipVertically1D as FlipV1D
from augmentation.augment import FlipHorizontally1D as FlipH1D
from augmentation.augment import RandomFlipping1D as RandF1D


@ddt
class TestMarginSampling1D(unittest.TestCase):
    
    def set_up(self):
        pass

    
    def tear_down(self):
        pass #del self.y_predict
        

    def test_FlipVertically1D_empty_array(self):
        empty = FlipV1D.calc(np.array([]))
        self.assertTrue(len(empty))
        #self.assertEqual(FlipV1D.calc(), 0)

I first assumed that somewhere I passed a self too much but this didnt solve my problem

user_1319284 · Answer

The issue is probably the ddt annotation. Normally, unittest test cases look exactly like your code, with no parameters other than self.

Example of unittest:

import unittest

class TestStringMethods(unittest.TestCase):

    def test_upper(self):
        self.assertEqual('foo'.upper(), 'FOO')

    def test_isupper(self):
        self.assertTrue('FOO'.isupper())
        self.assertFalse('Foo'.isupper())

    def test_split(self):
        s = 'hello world'
        self.assertEqual(s.split(), ['hello', 'world'])
        # check that s.split fails when the separator is not a string
        with self.assertRaises(TypeError):
            s.split(2)

if __name__ == '__main__':
    unittest.main()

But with ddt, this changes, they expect a second argument value:

https://ddt.readthedocs.io/en/latest/example.html

@ddt
class FooTestCase(unittest.TestCase):
    def test_undecorated(self):
        self.assertTrue(larger_than_two(24))

    @data(3, 4, 12, 23)
    def test_larger_than_two(self, value):
        self.assertTrue(larger_than_two(value))

Note that the first example (test_undecorated) looks like your code, so it seems like it's intended to work but maybe just doesn't and transforms the method anyway.

Unittest takes 1 positional argument but 2 were given

1 Answers