PyTest

Installing PyTest

• To install python, run the following command in the windows command prompt
   

pip install pytest==2.9.1

 

• After Installing to confirm the pytest installation run 
   

py.test -h

 

Basic PyTest

In this section, we will see how to use pytest by looking into some basic examples of pytest. Create a folder code_pytest. Create our test files inside these test files. Create a file name second_PyTest.py inside the folder. Add the below code and run it with the following command

py. test

Code:-

import pytest
def test_file1_method1():
  x=4
  y=6
  assert x+1 == y,"test failed"
  assert x == y,"test failed"
def test_file1_method2():
  x=4
  y=6
  assert x+1 == y,"test failed"

Output:-

Launching pytest with arguments Second_PyTest.py::test_file1_method2 --no-header --no-summary -q in C:\Users\Admin\PycharmProjects\PyTest

============================= test session starts =============================
collecting ... collected 1 item

Second_PyTest.py::test_file1_method2 FAILED                              [100%]
Second_PyTest.py:6 (test_file1_method2)
5 != 6

Expected :6
Actual   :5
<Click to see difference>

def test_file1_method2():
     x=4
     y=6
>    assert x+1 == y,"test failed"
E    AssertionError: test failed
E    assert (4 + 1) == 6


Second_PyTest.py:10: AssertionError

============================== 1 failed in 0.09s ==============================

Process finished with exit code 1

 

You can compile it with online python compiler.

Assertion in PyTest

Assertions in Pytest are used to check the return True or False status. In PyTest, if an assertion fails in a test method, then that particular method execution is stopped there itself. Pytest will not execute the remaining code of the method, and pytest assertion will continue with the following methods.

 

Example:

assert "hello" == "Hai" is an assertion failure.
assert 4==4 is a successful assertion
assert True is a successful assertion
assert False is an assertion failure.

 

Consider the following 

assert x == y,"test failed because x=" + str(x) + " y=" + str(y)

 

Place this code in our above test_file1_method1() instead of the following  assertion

assert x == y,"test failed"

 

On running the above code, we will get an assertion error.

Also read,  Python filename extensions

Identification of Test Methods and Test Files by PyTest

PyTest, by default, only identifies file names starting with test_ or ending with _test as the text files. Test Method names should start with "test".All other names are ignored by PyTest even if we ask pyTest to run those methods explicitly.
 

Valid Methods:-

test_login.py - valid
login_test.py - valid

Invalid Methods:-

firsttestlogin.py -invalid
loginfirsttest.py -invalid

Running Multiple tests from Specific files and multiple files

We have saved a file test_sample1.py inside our folder study_pytest. Now let us assume we have multiple files like test_sample2.py,test_sample3.py. To run all the tests from all the files in the folder and subfolders, we need to run the following pytest command.

py.test

 

The above command will run all the filenames starting with test_ and the filenames ending with _test in that folder and subfolders under that folder.Now to run tests only from a specific file, we use 

py.test <filename>
py.test test_sample1.py

Must Recommended Topic, Floor Division in Python and Convert String to List Python.

Frequently Asked Questions

What is PyTest?

PyTest is a testing framework that allows its users to write test codes using python.PyTest helps us write simple and scalable test cases for databases, APIs, or UI.

What is an Assertion in PyTest?

Assertions in Pytest are used to check the return True or False status. If any assertion fails in a test method, then that particular method execution is stopped there itself, and PyTest will not execute the remaining code of the method.

What are some advantages of using PyTest?

PyTest is open source and easy to start with because of its simple, easy and no boilerplate code syntax. It can run tests in parallel and run a subset of tests or specific tests.

How to Install PyTest using windows command prompt?

To install python, run the following command in the windows command prompt

pip install pytest==2.9.1

How to confirm the installation of PyTest?

To confirm the pytest installation run the “py.test -h” command in your command prompt           

Conclusion

This article extensively discussed the PyTest, a Python testing framework, and covered its installation, the Basic PyTest program and Assertion in PyTest, Its uses, and critical concepts.

After reading about the PyTest, are you not feeling excited to read/explore more articles on the topic of Python Testing? Don't worry; Coding Ninjas has you covered. To learn, see Testing Framework in Python, Testing in Python using DocTest, and Testify in Python.

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