Explore the pep517 branch issues

.github/workflows/ci.yml

@@ -24,30 +24,39 @@ jobs:
           - name: CPython 2.7
             tox: py27
             action: 2.7
+            major: 2
           - name: CPython 3.5
             tox: py35
             action: 3.5
+            major: 3
           - name: CPython 3.6
             tox: py36
             action: 3.6
+            major: 3
           - name: CPython 3.7
             tox: py37
             action: 3.7
+            major: 3
           - name: CPython 3.8
             tox: py38
             action: 3.8
+            major: 3
           - name: CPython 3.9
             tox: py39
             action: 3.9
+            major: 3
           - name: PyPy 2.7
             tox: pypy27
             action: pypy-2.7
+            major: 2
           - name: PyPy 3.6
             tox: pypy36
             action: pypy-3.6
+            major: 3
           - name: PyPy 3.7
             tox: pypy37
             action: pypy-3.7
+            major: 3
         task:
           - name: Test
             tox: tests
@@ -70,6 +79,12 @@ jobs:
 
     - uses: twisted/python-info-action@v1.0.1
 
+    - name: Try creating an env
+      if: matrix.python.major == 3
+      run: |
+        python -m venv a_unique_env_directory
+        tree /f a_unique_env_directory
+
     - name: Install dependencies
       run: python -m pip install --upgrade pip tox codecov
 

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"],
     package_dir={"": "src"},
     packages=find_packages("src"),

src/towncrier/newsfragments/314.feature.rst

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

tox.ini

@@ -1,5 +1,9 @@
 [tox]
 envlist = cov-erase, flake8, {pypy27,pypy36,pypy37,py27,py35,py36,py37,py38,py39}-{tests,flake8,check-manifest,check-newsfragment}, cov-report
+requires=
+    virtualenv>=20.0.35
+    tox-wheel>=0.6.0
+isolated_build=true
 skip_missing_envs = true
 
 [testenv:flake8]
@@ -29,7 +33,7 @@ deps =
    coverage
    incremental
    mock
-
+wheel = True
 commands =
    python -V
    coverage --version