Talks - Paul Ganssle: pytest for unittesters

PyTest is now considered the standard way to do testing in Python, with broad ecosystem support and active development

Allows incremental migration from unittest - can mix PyTest and unittest code in the same codebase while transitioning

Key advantages over unittest:

• Uses plain assert statements instead of assertion methods
• Provides detailed error messages with actual vs expected values
• Optional class usage - tests can be simple functions
• Powerful fixture system for test setup/teardown
• Built-in parameterized testing support
• Extensive plugin ecosystem

Fixtures provide modular, composable test setup:

• Can be used across multiple tests
• Support setup and teardown via yield
• Can be stacked and combined
• Allow parameter passing

Strong debugging capabilities:

• –pdb flag drops into debugger on test failure
• -L flag shows local variables
• –stepwise mode to run from last failure
• xdist plugin for parallel test execution

Configuration flexibility:

• Highly customizable through plugins
• Supports various output formats
• Can maintain existing unittest conventions while adopting PyTest features

Common concerns about “magic” behavior haven’t been problematic in practice:

• Test discovery conventions are configurable
• Assertion rewriting provides better error messages
• Core functionality is stable and well-tested

Testing Django:

• Works well with django-pytest plugin
• Some database fixture scenarios need special handling
• Active community support for Django integration