1 files changed, 82 insertions, 0 deletions
diff --git a/tools/tox_pip.py b/tools/tox_pip.py
new file mode 100644
index 00000000..9fe4f905
--- /dev/null
+++ b/tools/tox_pip.py
@@ -0,0 +1,82 @@
+import os
+import subprocess
+import sys
+import re
+
+
+def remove_setuptools():
+    """
+    Remove setuptools from the current environment.
+    """
+    print("Removing setuptools")
+    cmd = [sys.executable, '-m', 'pip', 'uninstall', '-y', 'setuptools']
+    # set cwd to something other than '.' to avoid detecting
+    # '.' as the installed package.
+    subprocess.check_call(cmd, cwd='.tox')
+
+
+def bootstrap():
+    print("Running bootstrap")
+    cmd = [sys.executable, '-m', 'bootstrap']
+    subprocess.check_call(cmd)
+
+
+def is_install_self(args):
+    """
+    Do the args represent an install of .?
+    """
+    def strip_extras(arg):
+        match = re.match(r'(.*)?\[.*\]$', arg)
+        return match.group(1) if match else arg
+
+    return (
+        'install' in args
+        and any(
+            arg in ['.', os.getcwd()]
+            for arg in map(strip_extras, args)
+        )
+    )
+
+
+def pip(*args):
+    cmd = [sys.executable, '-m', 'pip'] + list(args)
+    return subprocess.check_call(cmd)
+
+
+def test_dependencies():
+    from ConfigParser import ConfigParser
+
+    def clean(dep):
+        spec, _, _ = dep.partition('#')
+        return spec.strip()
+
+    parser = ConfigParser()
+    parser.read('setup.cfg')
+    raw = parser.get('options.extras_require', 'tests').split('\n')
+    return filter(None, map(clean, raw))
+
+
+def disable_python_requires():
+    """
+    On Python 2, install the dependencies that are selective
+    on Python version while honoring REQUIRES_PYTHON, then
+    disable REQUIRES_PYTHON so that pip can install this
+    checkout of setuptools.
+    """
+    pip('install', *test_dependencies())
+    os.environ['PIP_IGNORE_REQUIRES_PYTHON'] = 'true'
+
+
+def run(args):
+    os.environ['PIP_USE_PEP517'] = 'true'
+
+    if is_install_self(args):
+        remove_setuptools()
+        bootstrap()
+        sys.version_info > (3,) or disable_python_requires()
+
+    pip(*args)
+
+
+if __name__ == '__main__':
+    run(sys.argv[1:])