pytest is a Python testing framework to check that your code is doing what they should!

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17

# Import pytest
import pytest

# We define tests as functions
def test_something():
  pass

# We can also group our test methods into classes
class TestUS1():
  def test_normal_use(self):
    pass
    
  def test_no_items(self):
    pass
    
  def test_one_item(self):
    pass
  • Any python files that start with test_ or end with _test are included by pytest
  • Any class that starts with Test are included by pytest
  • Any method that starts with test_ are executed by pytest

Testing for Exceptions

1
2

with pytest.raises(ExceptionName):
  doSomethingThatRaisesAnException

Fixtures

If you have code which produces an object that runs for several tests, you can group them into a fixture

 1
 2
 3
 4
 5
 6
 7
 8
 9
10

@pytest.fixture
def mySystem():
  # do stuff
  sys = SomeSystemThing()
  sys.setValue(7)
  return sys

def test_checking(mySystem):
  # Fixture name here ^^^^
  assert mySystem.check() == True

Setup and Teardown

Another way to rerun the same piece of code multiple times is through a setup and teardown procedure.

Consider this excerpt from StackOverflow

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24

lh = <got log handler from logger module>

class TestClass:
    @classmethod
    def setup_class(cls):
        lh.info("starting class: {} execution".format(cls.__name__))

    @classmethod
    def teardown_class(cls):
        lh.info("starting class: {} execution".format(cls.__name__))

    def setup_method(self, method):
        lh.info("starting execution of tc: {}".format(method.__name__))

    def teardown_method(self, method):
        lh.info("starting execution of tc: {}".format(method.__name__))

    def test_tc1(self):
        <tc_content>
        assert 

    def test_tc2(self):
        <tc_content>
        assert

Now when I run my tests, when the TestClass execution is starting, it logs the details for when it is beginning execution, when it is ending execution and same for the methods..