Introduce pyproject.tomlbschubert/ensure-cython

Using pyproject.toml, defined in PEP518, allows us to have
an isolated build environment, ensuring that Cython can be installed
before calling setup.py in tox. This allows us to use cython helpers
in the setup.py script.

4 files changed, 21 insertions, 2 deletions

diff --git a/MANIFEST.in b/MANIFEST.in
index 729a3e957..1dace8a01 100644
--- a/MANIFEST.in
+++ b/MANIFEST.in
@@ -43,3 +43,6 @@ include requirements/plugin-requirements.txt
 
 # Versioneer
 include versioneer.py
+
+# setuptools.build_meta don't include setup.py by default. Add it
+include setup.py
diff --git a/pyproject.toml b/pyproject.toml
new file mode 100644
index 000000000..38bb870e3
--- /dev/null
+++ b/pyproject.toml
@@ -0,0 +1,8 @@
+[build-system]
+requires = [
+    # We need at least version 36.6.0 that introduced "build_meta"
+    "setuptools>=36.6.0",
+    # In order to build wheels, and as required by PEP 517
+    "wheel"
+]
+build-backend = "setuptools.build_meta"
diff --git a/setup.py b/setup.py
index c550fdd0b..097dd6a51 100755
--- a/setup.py
+++ b/setup.py
@@ -19,13 +19,15 @@
 #        Tristan Van Berkom <tristan.vanberkom@codethink.co.uk>
 
 import os
+from pathlib import Path
 import re
 import shutil
 import subprocess
 import sys
-import versioneer
 
-from pathlib import Path
+# Add local directory to the path, in order to be able to import versioneer
+sys.path.append(os.path.dirname(__file__))
+import versioneer
 
 
 ##################################################################
diff --git a/tox.ini b/tox.ini
index 6d5a7c575..d0c1f4452 100644
--- a/tox.ini
+++ b/tox.ini
@@ -4,6 +4,7 @@
 [tox]
 envlist = py{35,36,37}
 skip_missing_interpreters = true
+isolated_build = true
 
 #
 # Defaults for all environments
@@ -147,3 +148,8 @@ deps =
     -rrequirements/requirements.txt
     -rrequirements/dev-requirements.txt
     -rrequirements/plugin-requirements.txt
+
+# When building using PEP518 and 517, we don't want default dependencies
+# installed by the base environment.
+[testenv:.package]
+deps =