Now, we will start with our first pytest program. We will first create a directory and thereby, create our test files in the directory.

Let us follow the steps shown below −

• Create a new directory named automation and navigate into the directory in your command line.

• Create a file named test_square.py and add the below code to that file.

import math

def test_sqrt():
   num = 25
   assert math.sqrt(num) == 5

def testsquare():
   num = 7
   assert 7*7 == 40

def tesequality():
   assert 10 == 11

Run the test using the following command −

pytest

The above command will generate the following output −

test_square.py .F
============================================== FAILURES 
==============================================
______________________________________________ testsquare 
_____________________________________________
   def testsquare():
   num=7
>  assert 7*7 == 40
E  assert (7 * 7) == 40
test_square.py:9: AssertionError
================================= 1 failed, 1 passed in 0.06 seconds 
=================================

See the first line of the result. It displays the file name and the results. F represents a test failure and dot(.) represents a test success.

Below that, we can see the details of the failed tests. It will show at which statement the test has failed. In our example, 7*7 is compared for equality against 40, which is wrong. In the end, we can see test execution summary, 1 failed and 1 passed.

The function tesequality is not executed because pytest will not consider it as a test since its name is not of the format test*.

Now, execute the below command and see the result again −

pytest -v

-v increases the verbosity.

test_square.py::test_sqrt PASSED
test_square.py::testsquare FAILED
============================================== FAILURES 
==============================================
_____________________________________________ testsquare 
_____________________________________________
   def testsquare():
   num = 7
>  assert 7*7 == 40
E  assert (7 * 7) == 40
test_square.py:9: AssertionError
================================= 1 failed, 1 passed in 0.04 seconds 
=================================

Now the result is more explanatory about the test that failed and the test that passed.

Note − pytest command will execute all the files of format test_* or *_test in the current directory and subdirectories.