Implement PEP 518 and opt into PEP 517 builds

Author: dmtucker

MANIFEST.in

@@ -1,3 +1,5 @@
+include pyproject.toml
+
 # Include the README
 include *.md
 

pyproject.toml

@@ -0,0 +1,5 @@
+[build-system]
+# These are Pip's default requirements:
+# https://pip.pypa.io/en/stable/reference/pip/#pep-517-and-518-support
+requires = ["setuptools>=40.8.0", "wheel"]
+build-backend = "setuptools.build_meta"

tox.ini

@@ -13,8 +13,14 @@
 #  and also to help confirm pull requests to this project.
 
 [tox]
+minversion = 3.7.0
 envlist = py{27,35,36,37,38}
 
+# Activate isolated build environment. tox will use a virtual environment
+# to build a source distribution from the source tree. For build tools and
+# arguments use the pyproject.toml file as specified in PEP-517 and PEP-518.
+isolated_build = true
+
 [testenv]
 deps =
     check-manifest