chore: Use setuptools_scm to manage versioning

Summary
-------
Pilots whether we can abandon versioneer in all projects, as
setuptools_scm has minimal boilerplate.

Changes
-------
The setuptools_scm module is added to the pyproject.toml file,
as recommended in the documentation.
A tiny hack is added to the root ``__init__.py`` file, so that
the version is read from ``nitransforms/_version.py`` when that
file exists or it is interpolated via ``setuptools_scm.get_version``.

To make the version traverse into container images, before building,
``python setup.py --version`` must be invoked first (and it will create
the ``nitransforms/_version.py`` file.

``nitransforms/_version.py`` has been added to ``.gitignore`` to avoid
adding it by mistake.

Finally, the CircleCI workflow is also modified, so that the packaging
is always tested and installed versions are checked both for python
packages and docker distributions.

Resolves: #82

Author: oesteban

.circleci/config.yml

@@ -41,10 +41,12 @@ jobs:
                 docker push localhost:5000/ubuntu
             fi
     - checkout
+    - run: pyenv local 3.7.0
     - run:
         name: Build Docker image & push to registry
         no_output_timeout: 60m
         command: |
+            python3 setup.py --version
             e=1 && for i in {1..5}; do
                 docker build --rm --cache-from=nitransforms:latest \
                 -t nitransforms:latest \
@@ -63,6 +65,18 @@ jobs:
         key: build-v1-{{ .Branch }}-{{ epoch }}
         paths:
           - /tmp/docker
+    - run:
+        name: Check version packaged in Docker image
+        command: |
+            THISVERSION=$(python3 setup.py --version)
+            THISVERSION=${CIRCLE_TAG:-$THISVERSION}
+            INSTALLED_VERSION=$(\
+              docker run -it --rm --entrypoint=python nitransforms \
+                  -c 'import nitransforms as nit; print(nit.__version__)')
+            INSTALLED_VERSION=${INSTALLED_VERSION%$'\r'}
+            echo "VERSION: \"$THISVERSION\""
+            echo "INSTALLED: \"$INSTALLED_VERSION\""
+            test "$INSTALLED_VERSION" = "$THISVERSION"
     - run:
         name: Store FreeSurfer license file
         command: |
@@ -74,6 +88,72 @@ jobs:
         paths:
           - fslicense
 
+  test_package:
+    docker:
+      - image: circleci/python:3.7.4
+    working_directory: /tmp/src/nitransforms
+    steps:
+      - checkout
+      - run:
+          name: Setup Python environment with virtualenvs
+          command: |
+            python -m pip install --user --upgrade virtualenv pip
+      - run:
+          name: Prepare build environment
+          command: |
+            virtualenv --python=python3 /tmp/build
+            source /tmp/build/bin/activate
+            python3 -m pip install "setuptools ~= 42.0" "setuptools_scm[toml] >= 3.4" "pip>=10.0.1" \
+                twine docutils
+      - run:
+          name: Prepare install environments
+          command: |
+            virtualenv --python=python3 /tmp/install_sdist
+            source /tmp/install_sdist/bin/activate
+            python3 -m pip install "setuptools ~= 42.0" "setuptools_scm[toml] >= 3.4" "pip>=10.0.1"
+            deactivate
+            virtualenv --python=python3 /tmp/install_wheel
+            source /tmp/install_wheel/bin/activate
+            python3 -m pip install "setuptools ~= 42.0" "setuptools_scm[toml] >= 3.4" "pip>=10.0.1"
+      - run:
+          name: Build NiTransforms in build environment
+          command: |
+            source /tmp/build/bin/activate
+            python setup.py sdist bdist_wheel
+      - store_artifacts:
+          path: /tmp/src/nitransforms/dist
+      - run:
+          name: Check sdist package in build environment
+          command: |
+            source /tmp/build/bin/activate
+            twine check dist/nitransforms*
+      - run:
+          name: Install sdist package into install environment and check version
+          command: |
+            source /tmp/install_sdist/bin/activate
+            THISVERSION=$( python setup.py --version )
+            THISVERSION=${CIRCLE_TAG:-$THISVERSION}
+            pip install dist/nitransforms*.tar.gz
+            which nitransforms | grep install_sdist\\/bin
+            INSTALLED_VERSION=$(python -c 'import nitransforms as nit; print(nit.__version__)')
+            INSTALLED_VERSION=${INSTALLED_VERSION%$'\r'}
+            echo "VERSION: \"$THISVERSION\""
+            echo "INSTALLED: \"$INSTALLED_VERSION\""
+            test "$INSTALLED_VERSION" = "$THISVERSION"
+      - run:
+          name: Install wheel into install environment and check version
+          command: |
+            source /tmp/install_wheel/bin/activate
+            THISVERSION=$( python setup.py --version )
+            THISVERSION=${CIRCLE_TAG:-$THISVERSION}
+            pip install dist/nitransforms*.whl
+            which nitransforms | grep install_wheel\\/bin
+            INSTALLED_VERSION=$(python -c 'import nitransforms as nit; print(nit.__version__)')
+            INSTALLED_VERSION=${INSTALLED_VERSION%$'\r'}
+            echo "VERSION: \"$THISVERSION\""
+            echo "INSTALLED: \"$INSTALLED_VERSION\""
+            test "$INSTALLED_VERSION" = "$THISVERSION"
+
   test_pytest:
     machine:
       image: circleci/classic:201808-01
@@ -175,6 +255,14 @@ workflows:
             tags:
               only: /.*/
 
+      - test_package:
+          filters:
+            branches:
+              ignore:
+                - /docs?\/.*/
+            tags:
+              only: /.*/
+
       - test_pytest:
           requires:
             - build
@@ -186,9 +274,10 @@ workflows:
             tags:
               only: /.*/
 
-      - test_packaging_and_deploy:
+      - deploy_pypi:
           requires:
             - test_pytest
+            - test_package
           filters:
             branches:
               ignore: /.*/

.gitignore

@@ -1,3 +1,6 @@
+# setuptools-scm
+nitransforms/_version.py
+
 # Byte-compiled / optimized / DLL files
 __pycache__/
 *.py[cod]

nitransforms/__init__.py

@@ -18,7 +18,21 @@
 """
 from .linear import Affine
 from .nonlinear import DisplacementsFieldTransform
-from .io import afni, fsl, itk
 
+try:
+    from ._version import version as __version__
+except ModuleNotFoundError:
+    from pkg_resources import get_distribution, DistributionNotFound
+    try:
+        __version__ = get_distribution('nitransforms').version
+    except DistributionNotFound:
+        __version__ = 'unknown'
+    del get_distribution
+    del DistributionNotFound
 
-__all__ = ['afni', 'fsl', 'itk', 'Affine', 'DisplacementsFieldTransform']
+
+__all__ = [
+    'Affine',
+    'DisplacementsFieldTransform',
+    '__version__',
+]

pyproject.toml

@@ -0,0 +1,10 @@
+[build-system]
+requires = ["setuptools ~= 42.0", "wheel", "setuptools_scm[toml] >= 3.4"]
+
+[tool.setuptools_scm]
+write_to = "nitransforms/_version.py"
+write_to_template = """\
+\"\"\"Version file, automatically generated by setuptools_scm.\"\"\"
+__version__ = "{version}"
+"""
+fallback_version = "0.0"

setup.cfg

@@ -14,6 +14,9 @@ test_requires =
     pytest-cov
     nose
     codecov
+setup_requires =
+    setuptools_scm
+    toml
 packages = find:
 include_package_data = True
 

setup.py

@@ -1,6 +1,13 @@
+"""Prepare package for distribution."""
+from pathlib import Path
 from setuptools import setup
+from toml import loads
 
 if __name__ == "__main__":
+    scm_cfg = loads(
+        (Path(__file__).parent / "pyproject.toml").read_text()
+    )["tool"]["setuptools_scm"]
     setup(
         name="nitransforms",
+        use_scm_version=scm_cfg,
     )