In this tutorial, we will learn how to use PyTest as a backend engineers.
PyTest is a popular Python testing framework. It is wisely use by backend engineers to test their applications for efficient and maintainable. It offers a simple syntax, powerful features, and extensive plugin support. It is suitable for testing a wide range of application, including web servers, APIs, databases, and many more.
Features of PyTest
Simple Syntax
It provides writing tests using Python's standard assert statements. The tests can write in a readable manner so that it will be easy for developers to understand and maintain the code.
Fixture Support:
It is the reusable pieces of setup and teardown code that can be shared across multiple tests. Fixtures help in reducing code duplication and making tests more maintainable.
Parameterized Testing:
Parameterized enable us to run the same test with different input parameters. This is particularly useful for testing functions or methods with multiple input scenarios.
Powerful Assertions:
It provides a wide range of built-in assertions for verifying the behavior of your code. PyTest supports advanced assertions such as assertRaises, assertWarns, and assertRegex.
Plugin System:
It has the robust plugin architecture that allows developers to extend its functionality according to the requirements. PyTest has many third-party plugins available.
Integration with other tools:
PyTest can integrates with other testing tools and framewords, such as coverage.py for code coverage analysis, tox for test automation, and Django for testing Django applications.
Test Discovery and Execution:
PyTest automatically discovers and executes test cases based on naming conventions and directory structures, eliminating the need for explicit configuration in most cases.
Support for Asynchronous Testing:
PyTest provides support for testing asynchronous code using native Python coroutines and async/await syntax.
Implement PyTest
We have seen the overview and features of the PyTest. Now, let's use the PyTest in our simple code.
First, we need to install PyTest, we can do it using pip command. Execute following command:
pip install pytest
Next, create a Python file and write a simple code. PyTest discover test files are typically have names that start with test_ or ends with _test.py. We can write test function also. Each test function should start with test_ by convention and we can use PyTest's assertion methods to verify the behavior of your code.
Let's create two files with the named calculator.py with function add that adds two number(We can add more function) and test_calculator.py for testing. Use your faviorite editor:
nano calculator.py
Add following code:
def add(x, y):
return x + y
Save and exit
Now, create test file:
nano test_calculator.py
Add following code:
from calculator import add
def test_add():
assert add(2, 3) == 5
assert add(0, 0) == 0
assert add(-1, 1) == 0
Save and exit.
Here, in test_calculator file, we have imported add function from calculator.py file and wrote three test cases using PyTest's assert statement.
Test Our Code
Now, let's run the test. There are two ways we can run the test. First, navigate to the directory that contain test file with named test_ file and execute following command:
pytest
Second way is, mention the test file or directories as arguments to the pytest command:
pytest test_calculator.py
Output:
================================= test session starts ===============================
platform linux -- Python 3.10.12, pytest-8.0.0, pluggy-1.4.0
rootdir: /root
collected 1 item
test_calculator.py . [100%]
================================= 1 passed in 0.01s =================================
It is the basic overview of implementing PyTest for testing Python code. We have seen how to use PyTest as a backend engineers.
