Write simple assert statements to debug failures and scale to complex functional tests
Imagine a screen that shows you at a glance which value differed from expectations when a test fails. pytest simplifies debugging by providing detailed failure information using only plain assert statements. It is a Python testing framework that handles everything from small unit tests to full application functional tests with the same tool.
Detailed failure information from assert statements alone
pytest outputs detailed information about how values differed in failed assert statements. Developers do not need to remember specific verification function names; they only need to write plain assert statements. For example, if inc(3) == 5 fails, it clearly indicates that the actual result was 4. This detailed output reduces the time spent tracking down bugs.
Automatic discovery and flexible resource management
pytest automatically finds and runs test modules and functions. It also manages resources needed for tests through modularized components called fixtures. These resources apply flexibly, whether for small unit tests or parameterized long-lifecycle tests. Existing unittest or trial test suites can be run directly without separate conversion.
Over 1,300 plugins and supported environments
pytest features a rich plugin architecture and supports over 1,300 external plugins. This indicates that the community is growing actively. It requires a Python 3.10 or higher or PyPy3 environment, and if this condition is met, it can be applied to various projects. The documentation site provides installation methods, tutorials, and PDF materials.
Things to check before adoption
Projects using a Python 3.10 or higher or PyPy3 environment can adopt pytest. It is distributed under the MIT license, allowing free use. If you discover a security vulnerability, you must report it through the security advisory channel rather than the issue tracker. Commercial support for enterprises is provided through Tidelift subscriptions, so consider that option if commercial support is needed.