CODEWITHSUNDEEP
pythonunit-testingtddbdd
evkline
evkline

Reputation: 1511

What is the canonical way to isolate unit tests in Python with assertion-style tests?

I recently asked this question and realized that I'd also like to know if there's a way to achieve 'expectation' isolation with assertion-style tests. I've copy and pasted a simple example of what I mean by 'expectation' isolation.

I'm relatively new to Python, coming from Ruby/JavaScript and having testing libraries like Rspec and Jasmine has provided me with the ability to isolate 'expectations' when testing a single function. Since there doesnt seem to be an 'expectation'-style library for Python that is actively maintained, I was wondering if there's a way to achieve an equivalent testing style with either unittest or pytest (the 2 most popular Python testing libraries from what I understand).

foo.py

class Foo():
    def bar(self, x):
        return x + 1

Expectation-Style/Describe-It

test_foo.py

describe Foo:
    describe self.bar:
        before_each:
            f = Foo()

        it 'returns 1 more than its arguments value':
            expect f.bar(3) == 4

        it 'raises an error if no argument is passed in':
            expect f.bar() raiseError

Unittest/assertion-style

test_foo.py

 class Foo():
     def test_bar(x):
         x = 3
         self.assertEqual(4)
         x = None
         self.assertRaises(Error)

Upvotes: 4

Views: 1485

Answers (1)

chepner
chepner

Reputation: 531075

The unittest module is part of the standard library.

class TestFoo(unittest.TestCase):
    def setUp(self):
        self.f = Foo()

    def test_bar(self):
        self.assertEqual(self.f.bar(3), 4)

    def test_missing_argument(self):
        self.assertRaises(TypeError, self.f.bar())

Upvotes: 1

Related Questions