This project comes with a full test suite. To install development and testing dependencies, use:

pip install -e ".[test]"

To also install 3rd party JSON libraries used for running benchmarks, use:

pip install -e ".[benchmark]"

To run the tests, just type pytest. To also run the benchmarks, use pytest --runslow. --runslow will also run the NumPy integration tests.

To properly test builds on Windows, you need both a recent version of Visual Studio as well as VS2015, patch 3. Older versions of CPython required portable C/C++ extensions to be built with the same version of VS as the interpreter. Use the Developer Command Prompt to easily switch between versions.


pysimdjson is written using Cython. However, by default will use the already-generated csimdjson.cpp instead of regenerating it. This is to avoid making Cython an install-time requirement.

To force the usage of Cython, use BUILD_WITH_CYTHON:

BUILD_WITH_CYTHON=1 python develop

This will cause Cython to regenerate the csimdjson.cpp from the csimdjson.pyx and csimdjson.pxd files.