To test Python code, use the built-in unittest framework or the cleaner pytest library. 1. When using unittest, you need to create a test class inherited from unittest.TestCase, write a method that starts with test_, and use assertions to verify the result. 2. pytest does not require inheriting classes, just write a function that starts with test_ and use a normal assert statement. 3. During testing, boundary conditions, invalid input and exception handling should be covered, such as checking for zero-deletion errors. 4. Test automation can be achieved through Git hooks, CI/CD tools (such as GitHub Actions) or IDE integration to ensure that each submission is verified, thereby improving code quality and development efficiency.
Testing Python code is a cruel part of development — it helps catch bugs early and ensures your code behaves as expected. The key idea is to write tests that validate the logic of your functions, classes, or entire modules.
Use Built-in Testing Tools Like unittest
Python comes with a built-in testing framework called unittest
. It's inspired by Java's JUnit and supports test automation, setup and teardown routines, and more.
Here's how you can use it:
- Create a test class that inherits from
unittest.TestCase
- Write methods that start with
test_
(this naming convention tells unittest it's a test method) - Use assertions like
self.assertEqual()
,self.assertTrue()
, etc., to check outcomes
Example:
import unittest def add(a, b): return ab class TestMathFunctions(unittest.TestCase): def test_add(self): self.assertEqual(add(2, 3), 5) self.assertEqual(add(-1, 1), 0) if __name__ == '__main__': unittest.main()
Run this script, and unittest will run your tests and report any failures.
Try pytest
for Simpler, More Flexible Testing
If you want something less verbose than unittest
, try pytest
. It allows you to write smaller, cleaner test files without needing to subclass anything.
To get started:
- Install pytest:
pip install pytest
- Write a function that starts with
test_
- Run
pytest
in your terminal
Example:
def multiply(a, b): return a * b def test_multiply(): assert multiply(2, 3) == 6 assert multiply('a', 3) == 'aaa'
Just save this as test_math.py
and run pytest
. If all assertions pass, you'll see a success message.
One big advantage of pytest is its ecosystem — plugins like pytest-cov
help measure test coverage, and others make integration testing easier.
Don't Forget Edge Cases and Input Validation
It's easy to test the "happy path" — when everything works as expected — but real-world code often runs into unexpected inputs.
Make sure to test:
- Invalid types (eg, passing a string where an int is expected)
- Boundary conditions (like empty lists or zero)
- Error handling (does your code raise exceptions correctly?)
For example:
def divide(a, b): if b == 0: raise ValueError("Cannot divide by zero") return a / b def test_divide(): assert divide(10, 2) == 5 with pytest.raises(ValueError): divide(1, 0)
This way, you're not just checking what works — you're also making sure errors are handled properly.
Automate Your Tests Where Possible
Running tests manually every time gets old fast. You can integrate testing into your workflow using:
- Git hooks (to run tests before commits)
- CI/CD tools like GitHub Actions, GitLab CI, or Travis CI
- IDE integrations (many editors highlighting failing tests inline)
Set up a simple CI pipeline to run tests automatically on every push. That way, even if you forget to run them locally, you'll know if something breaks.
Basically that's it. Writing good tests take practice, but once you get the hang of it, it becomes second nature — and saves a lot of debugging time later.
The above is the detailed content of How do I test Python code?. For more information, please follow other related articles on the PHP Chinese website!

Hot AI Tools

Undress AI Tool
Undress images for free

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Clothoff.io
AI clothes remover

Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Article

Hot Tools

Notepad++7.3.1
Easy-to-use and free code editor

SublimeText3 Chinese version
Chinese version, very easy to use

Zend Studio 13.0.1
Powerful PHP integrated development environment

Dreamweaver CS6
Visual web development tools

SublimeText3 Mac version
God-level code editing software (SublimeText3)

Hot Topics

The key to dealing with API authentication is to understand and use the authentication method correctly. 1. APIKey is the simplest authentication method, usually placed in the request header or URL parameters; 2. BasicAuth uses username and password for Base64 encoding transmission, which is suitable for internal systems; 3. OAuth2 needs to obtain the token first through client_id and client_secret, and then bring the BearerToken in the request header; 4. In order to deal with the token expiration, the token management class can be encapsulated and automatically refreshed the token; in short, selecting the appropriate method according to the document and safely storing the key information is the key.

To test the API, you need to use Python's Requests library. The steps are to install the library, send requests, verify responses, set timeouts and retry. First, install the library through pipinstallrequests; then use requests.get() or requests.post() and other methods to send GET or POST requests; then check response.status_code and response.json() to ensure that the return result is in compliance with expectations; finally, add timeout parameters to set the timeout time, and combine the retrying library to achieve automatic retry to enhance stability.

In Python, variables defined inside a function are local variables and are only valid within the function; externally defined are global variables that can be read anywhere. 1. Local variables are destroyed as the function is executed; 2. The function can access global variables but cannot be modified directly, so the global keyword is required; 3. If you want to modify outer function variables in nested functions, you need to use the nonlocal keyword; 4. Variables with the same name do not affect each other in different scopes; 5. Global must be declared when modifying global variables, otherwise UnboundLocalError error will be raised. Understanding these rules helps avoid bugs and write more reliable functions.

To create modern and efficient APIs using Python, FastAPI is recommended; it is based on standard Python type prompts and can automatically generate documents, with excellent performance. After installing FastAPI and ASGI server uvicorn, you can write interface code. By defining routes, writing processing functions, and returning data, APIs can be quickly built. FastAPI supports a variety of HTTP methods and provides automatically generated SwaggerUI and ReDoc documentation systems. URL parameters can be captured through path definition, while query parameters can be implemented by setting default values ??for function parameters. The rational use of Pydantic models can help improve development efficiency and accuracy.

Add timeout control to Python's for loop. 1. You can record the start time with the time module, and judge whether it is timed out in each iteration and use break to jump out of the loop; 2. For polling class tasks, you can use the while loop to match time judgment, and add sleep to avoid CPU fullness; 3. Advanced methods can consider threading or signal to achieve more precise control, but the complexity is high, and it is not recommended for beginners to choose; summary key points: manual time judgment is the basic solution, while is more suitable for time-limited waiting class tasks, sleep is indispensable, and advanced methods are suitable for specific scenarios.

How to efficiently handle large JSON files in Python? 1. Use the ijson library to stream and avoid memory overflow through item-by-item parsing; 2. If it is in JSONLines format, you can read it line by line and process it with json.loads(); 3. Or split the large file into small pieces and then process it separately. These methods effectively solve the memory limitation problem and are suitable for different scenarios.

In Python, the method of traversing tuples with for loops includes directly iterating over elements, getting indexes and elements at the same time, and processing nested tuples. 1. Use the for loop directly to access each element in sequence without managing the index; 2. Use enumerate() to get the index and value at the same time. The default index is 0, and the start parameter can also be specified; 3. Nested tuples can be unpacked in the loop, but it is necessary to ensure that the subtuple structure is consistent, otherwise an unpacking error will be raised; in addition, the tuple is immutable and the content cannot be modified in the loop. Unwanted values can be ignored by \_. It is recommended to check whether the tuple is empty before traversing to avoid errors.

Python default parameters are evaluated and fixed values ??when the function is defined, which can cause unexpected problems. Using variable objects such as lists as default parameters will retain modifications, and it is recommended to use None instead; the default parameter scope is the environment variable when defined, and subsequent variable changes will not affect their value; avoid relying on default parameters to save state, and class encapsulation state should be used to ensure function consistency.
