To develop, we suggest using virtual environments together with pip or using pipenv. Once the environment is activated, clone the repo from GitHub

git clone

and install all necessary packages for development

python -m pip install --ignore-installed -U -e .[complete]

Then setup the Git pre-commit hook for Black by running

pre-commit install

as the rev gets updated through time to track changes of different hooks, simply run

pre-commit autoupdate

to have pre-commit install the new version.


Data Files

A function-scoped fixture called datadir exists for a given test module which will automatically copy files from the associated test modules data directory into a temporary directory for the given test execution. That is, for example, if a test was defined in, then data files located in test_schema/ will be copied to a temporary directory whose path is made available by the datadir fixture. Therefore, one can do:

def test_patchset(datadir):
    data_file = open(datadir.join('test.txt'))

which will load the copy of text.txt in the temporary directory. This also works for parameterizations as this will effectively sandbox the file modifications made.


pyhf tests packaging and distributing by publishing each commit to master to TestPyPI. In addition, installation of the latest test release from TestPyPI can be tested with

python -m pip install --extra-index-url --pre pyhf


This adds TestPyPI as an additional package index to search when installing pyhf specifically. PyPI will still be the default package index pip will attempt to install from for all dependencies.


Publishing to PyPI and TestPyPI is automated through the PyPA’s PyPI publish GitHub Action and the pyhf Tag Creator GitHub Actions workflow. A release can be created from any PR created by a core developer by adding a bumpversion tag to it that corresponds to the release type: major, minor, patch. Once the PR is tagged with the label, the GitHub Actions bot will post a comment with information on the actions it will take once the PR is merged. When the PR has been reviewed, approved, and merged, the Tag Creator workflow will automatically create a new release with bumpversion and then deploy the release to PyPI.