Add build-system to pyproject.toml for PEP 517 (-m build)

.github/workflows/ci.yml

@@ -6,10 +6,54 @@ on:
   pull_request:
     branches: [ master ]
 
+defaults:
+  run:
+    shell: bash
+
 jobs:
+  build:
+    name: ${{ matrix.task.name}} - ${{ matrix.os.name }} ${{ matrix.python.name }}
+    runs-on: ${{ matrix.os.runs-on }}
+    strategy:
+      fail-fast: false
+      matrix:
+        os:
+          - name: Linux
+            runs-on: ubuntu-latest
+        python:
+          - name: CPython 3.8
+            tox: py38
+            action: 3.8
+        task:
+          - name: Build
+            tox: build
+
+    steps:
+    - uses: actions/checkout@v2
+
+    - name: Set up ${{ matrix.python.name }}
+      uses: actions/setup-python@v2
+      with:
+        python-version: ${{ matrix.python.action }}
+
+    - name: Install dependencies
+      run: python -m pip install --upgrade pip tox
+
+    - uses: twisted/python-info-action@v1
+
+    - name: Tox
+      run: tox -c tox.ini -e ${{ matrix.task.tox }}
+
+    - name: Publish
+      uses: actions/upload-artifact@v2
+      with:
+        name: dist
+        path: dist/
+
   test:
     name: ${{ matrix.task.name}} - ${{ matrix.os.name }} ${{ matrix.python.name }}
     runs-on: ${{ matrix.os.runs-on }}
+    needs: build
     strategy:
       fail-fast: false
       matrix:
@@ -55,18 +99,24 @@ jobs:
     steps:
     - uses: actions/checkout@v2
 
+    - name: Download package files
+      uses: actions/download-artifact@v2
+      with:
+        name: dist
+        path: dist/
+
     - name: Set up ${{ matrix.python.name }}
       uses: actions/setup-python@v2
       with:
         python-version: ${{ matrix.python.action }}
 
-    - uses: twisted/python-info-action@v1.0.1
-
     - name: Install dependencies
       run: python -m pip install --upgrade pip tox codecov
 
-    - name: Test
-      run: tox -c tox.ini -e ${{ matrix.python.tox }}-tests
+    - uses: twisted/python-info-action@v1
+
+    - name: Tox
+      run: tox -c tox.ini --installpkg dist/*.whl -e ${{ matrix.python.tox }}-tests
 
     - name: Codecov
       run: |
@@ -102,18 +152,19 @@ jobs:
       with:
         python-version: ${{ matrix.python.action }}
 
-    - uses: twisted/python-info-action@v1.0.1
-
     - name: Install dependencies
       run: python -m pip install --upgrade pip tox
 
-    - name: Check
+    - uses: twisted/python-info-action@v1
+
+    - name: Tox
       run: tox -c tox.ini -e ${{ matrix.task.tox }}
 
   all:
     name: All
     runs-on: ubuntu-latest
     needs:
+      - build
       - test
       - check
     steps:

MANIFEST.in

@@ -4,6 +4,7 @@ include LICENSE
 include CODE_OF_CONDUCT.md
 include pyproject.toml
 include tox.ini
+include tox_build.sh
 recursive-include src *.rst
 
 exclude bin

pyproject.toml

@@ -53,3 +53,11 @@ exclude = '''
   )/
 )
 '''
+
+[build-system]
+requires = [
+    "setuptools ~= 44.1.1",
+    "wheel ~= 0.36.2",
+    "incremental == 17.5.0",
+]
+build-backend = "setuptools.build_meta"

setup.py

@@ -4,6 +4,11 @@
 
 from setuptools import setup, find_packages
 
+# If incremental is not present then setuptools just silently uses v0.0.0 so
+# let's import it and fail instead.
+import incremental
+
+
 setup(
     name="towncrier",
     maintainer="Amber Brown",
@@ -36,7 +41,6 @@
         "Programming Language :: Python :: Implementation :: PyPy",
     ],
     use_incremental=True,
-    setup_requires=["incremental"],
     install_requires=["click", "click-default-group", "incremental", "jinja2", "toml"],
     extras_require={"dev": ["packaging"]},
     package_dir={"": "src"},

src/towncrier/newsfragments/314.feature.rst

@@ -0,0 +1 @@
+Support building with PEP 517.

tox.ini

@@ -1,5 +1,6 @@
 [tox]
 envlist = cov-erase, flake8, {pypy27,pypy36,pypy37,py27,py35,py36,py37,py38,py39}-{tests,flake8,check-manifest,check-newsfragment}, cov-report
+isolated_build=true
 skip_missing_envs = true
 
 [testenv:flake8]
@@ -40,18 +41,31 @@ commands =
    coverage run -p --module twisted.trial {posargs:towncrier}
    coverage combine -a
 
+[testenv:build]
+allowlist_externals =
+   bash
+changedir = {envtmpdir}
+deps =
+   build
+setenv =
+   toxinidir={toxinidir}
+skip_install = true
+commands =
+   # could be brought inside tox.ini after https://github.com/tox-dev/tox/issues/1571
+   bash {toxinidir}/tox_build.sh
+
 [testenv:cov-report]
 deps =
    coverage
-
+skip_install = true
 commands =
    coverage html
    coverage report
 
 [testenv:cov-erase]
 deps =
    coverage
-
+skip_install = true
 commands =
    coverage erase
 

tox_build.sh

@@ -0,0 +1,6 @@
+# build the sdist
+python -m build --sdist --outdir ${toxinidir}/dist/ ${toxinidir}
+tar -xvf ${toxinidir}/dist/*
+cd *
+# build the wheel from the sdist
+python -m build --wheel --outdir ${toxinidir}/dist/ .