CODEWITHSUNDEEP
pythonpython-3.xtesting
Jad S
Jad S

Reputation: 3015

How to unit test if function output list of dictionaries?

I'm writing a unit test for a function that returns a list of dictionaries. What is the best way to check if the output is as expected? Here, "as expected" means the dictionaries in the lists have the same keys and values, irrespective of the order of keys within the dictionary, or of the dictionary's order within the list. So something like this:

expect_output = [ {"c":4} , {"a" : 4 , "b" : 3}]
actual_ouput = [{"b" : 3, "a" : 4 }, {"c":4}]
# some function that would return true in this case.

Upvotes: 24

Views: 19262

Answers (2)

JaDogg
JaDogg

Reputation: 1313

Here I've done a simple comparison between assertEqual and assertCountEqual as a value addition.

For assertEqual -> order of the list is important.

For assertCountEqual -> order of the list is not important.

def test_swapped_elements_1(self):
    self.assertEqual([{"b": 1}, {"a": 1, "b": 1}], [{"b": 1, "a": 1}, {"b": 1}])

def test_swapped_elements_2(self):
    self.assertCountEqual([{"b": 1}, {"a": 1, "b": 1}], [{"b": 1, "a": 1}, {"b": 1}])

def test_non_swapped_elements_1(self):
    self.assertEqual([{"a": 1, "b": 1}, {"b": 1}], [{"b": 1, "a": 1}, {"b": 1}])

def test_non_swapped_elements_2(self):
    self.assertCountEqual([{"a": 1, "b": 1}, {"b": 1}], [{"b": 1, "a": 1}, {"b": 1}])

Above results in:

PyCharm Screenshot

What failed one says: enter image description here

Therefore assertCountEqual should be used for OP's case.

This test was done in PyCharm latest version and Python 3.5

Upvotes: 4

chepner
chepner

Reputation: 531693

If you are using unittest, there is a method for this:

self.assertItemsEqual(actual_output, expected_output)

In Python-3, this method is renamed to assertCountEqual

Upvotes: 25

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