Pytest plugin for Blender testing. Executes your pytest testsuite with Blender in headless mode using its builtin Python interpreter.

pip install pytest-blender

Before execute it, you need to install your testing dependencies inside the builtin Blender Python interpreter. To get the interpreter location you can use the CLI utility pytest-blender, something like:

blender_python="$(pytest-blender)"
$blender_python -m ensurepip
$blender_python -m pip install -r test-requirements.txt

You can also get the intepreter for a custom Blender installation location with --blender-executable option:

pytest-blender --blender-executable ~/blender-2.91.2-linux64/blender

After installing dependencies, just call pytest as usually.

pytest -svv

Blender 2.82 (sub 7)
Read prefs: ~/.config/blender/2.82/config/userpref.blend
========================= test session starts ==================================
platform linux -- Python 3.8.5, pytest-6.1.2, py-1.9.0, pluggy-0.13.1 -- /usr/bin/blender
cachedir: .pytest_cache
rootdir: /home/mondeja/files/code/pytest-blender
collected 1 item

tests/test_bpy_import.py::test_inside_blender <module 'bpy' from '/usr/share/blender/scripts/modules/bpy/__init__.py'>
PASSED
=========================== 1 passed in 0.01s ==================================

You can specify a custom blender executable path using --blender-executable option:

pytest --blender-executable ~/blender-2.91.2-linux64/blender

Blender 2.91.2 (hash 5be9ef417703 built 2021-01-19 16:16:34)
Read prefs: ~/.config/blender/2.91/config/userpref.blend
found bundled python: ~/blender-2.91.2-linux64/2.91/python
============================ test session starts ===============================
platform linux -- Python 3.7.7, pytest-6.2.2, py-1.10.0, pluggy-0.13.1
rootdir: ~/pytest-blender
collected 1 item

tests/test_bpy_import.py .                                                [100%]

============================== 1 passed in 0.00s ===============================

When you call pytest, all options like --blender-executable are passed to the pytest suite running pytest-blender. If you want to pass arguments to blender in its headless execution, add a -- between pytest and blender arguments. If you want to pass arguments to the python Blender's interpreter, you need to add another -- between arguments in a third group.

For example:

pytest -svv --blender-executable ~/blender -- --enable-event-simulate -- -b

In case that you don't want to pass arguments to blender but yes to python, use double arguments group separation (-- --):

pytest -svv -- -- -b

You can use the --blender-template argument to pass a custom startup file:

pytest -svv --blender-template ~/.config/blender/2.93/config/startup.blend

Sometimes is useful to print debugging messages from pytest_blender. You can enable logging in your conftest.py file by the next way:

import logging

pytest_blender_logger = logging.getLogger("pytest_blender")
pytest_blender_logger.setLevel(logging.DEBUG)
pytest_blender_logger.addHandler(logging.StreamHandler())

# blender_executable ⇒ str

Returns the path of the executable that has started the current Blender session.

# blender_version ⇒ str

Returns the version of Blender running in the current session.

# blender_python_executable ⇒ str

Returns the path of the Python executable builtin in the Blender release of the currently running session.

# blender_python_version ⇒ str

Returns the version of the Python executable builtin in the Blender release of the currently running session.

# blender_addons_dir ⇒ str

Returns the scripts/addons directory of Blender (see [Blender Directory Layout), the directory in which by default are located the addons installed using the install_addons_from_dir fixture.

It tries to get it using the BLENDER_USER_SCRIPTS environment variable, but if is not defined attempts to discover it from the PATH.

# install_addons_from_dir(addons_dir, addon_module_names=None, save_userpref=True, default_set=True, persistent=True, quiet=True, **kwargs) ⇒ list

Function that installs and enables a set of addons which are located in a directory. By "addons" Blender understands Python scripts whose file names end with .py or .zip files for packages with multiple modules.

This function is designed to be executed before the pytest session to install the addons that you want to test, using the others fixtures disable_addons or uninstall_addons to disable or remove them after the execution of the test suite:

import os

import pytest

@pytest.fixture(scope="session", autouse=True)
def register_addons(install_addons_from_dir, disable_addons):
    addon_module_names = install_addons_from_dir(os.path.abspath("src"))
    yield
    disable_addons(addon_module_names)

import os

import pytest

@pytest.fixture(scope="session", autouse=True)
def register_addons(install_addons_from_dir, uninstall_addons):
    addon_module_names = install_addons_from_dir(os.path.abspath("src"))
    yield
    uninstall_addons(addon_module_names)

The difference between disabling addons and uninstalling them is that disabling removes the files from the Blender's addons directory but disabling keep the files there, allowing you to enable it manually from the preferences.

• addons_dir (str) Directory in which are located the files of the addons.
• addon_module_names (list) Name of the addons modules. If not defined (default) these will be discovered searching for addons in addons_dir directory.
• save_userpref (bool) Save user preferences after installation.
• default_set (bool) Set the user-preference calling addon_utils.enable.
• persistent (bool) Ensure the addon is enabled for the entire session (after loading new files).
• quiet (bool) If enabled, don't show stdout produced installing addons.
• **kwargs (dict) Subsecuent keyword arguments are passed to bpy.ops.preferences.addon_install.

Returns the addon module names as a list, ready to be passed to disable_addons or uninstall_addons.

# disable_addons(addon_module_names, save_userpref=True, default_set=True, quiet=True, **kwargs)

Function that disables a set of addons by module name. Is designed to disable your addons after a pytest suite execution (check install_addons_from_dir for an example).

• addon_module_names (list) Name of the addons modules as is returned by install_addons_from_dir.
• save_userpref (bool) Save user preferences after installation.
• default_set (bool) Set the user-preference calling addon_utils.disable.
• quiet (bool) If enabled, don't show stdout produced disabling addons.
• **kwargs (dict) Subsecuent keyword arguments are passed to addon_utils.disable.

# uninstall_addons(addon_module_names, quiet=True)

Function that uninstall a set of addons by module name. Is designed to remove your addons from the Blender's addons directory after a pytest suite execution (check install_addons_from_dir for an example).

• addon_module_names (list) Name of the addons modules as is returned by install_addons_from_dir.
• quiet (bool) If enabled, don't show stdout produced disabling addons.

You can use blender-downloader to download multiple versions of Blender in your CI and test against them. There is an example for Github Actions in the CI configuration of this repository:

jobs:
  test:
    name: Test
    runs-on: ${{ matrix.platform }}
    strategy:
      matrix:
        platform:
          - ubuntu-latest
          - macos-latest
        blender-version:
          - '3.1.2'
          - '2.93.9'
          - '2.83.9'
    steps:
      - uses: actions/checkout@v3
      - name: Set up Python v3.9
        uses: actions/setup-python@v3
        with:
          python-version: 3.9
      - name: Upgrade PIP
        run: python -m pip install --upgrade pip
      - name: Cache Blender ${{ matrix.blender-version }}
        uses: actions/cache@v3
        id: cache-blender
        with:
          path: |
            blender-*
            _blender-executable-path.txt
          key: ${{ runner.os }}-${{ matrix.blender-version }}
      - name: Download Blender ${{ matrix.blender-version }}
        if: steps.cache-blender.outputs.cache-hit != 'true'
        id: download-blender
        run: |
          python -m pip install --upgrade blender-downloader
          echo "$(blender-downloader \
          ${{ matrix.blender-version }} --extract --remove-compressed \
          --quiet --print-blender-executable)" > _blender-executable-path.txt
      - name: Install dependencies
        id: install-dependencies
        run: |
          python -m pip install .[test]
          blender_executable="$(< _blender-executable-path.txt tr -d '\n')"
          python_blender_executable="$(pytest-blender --blender-executable $blender_executable)"
          $python_blender_executable -m ensurepip
          $python_blender_executable -m pip install pytest
          echo "::set-output name=blender-executable::$blender_executable"
      - name: Test with pytest
        run: pytest -svv --blender-executable "${{ steps.install-dependencies.outputs.blender-executable }}" tests

• Latest version that officially supports Python3.6 is v1.2.1.