fix possible error when finalizing `install_requires`

1 files changed, 19 insertions, 0 deletions

diff --git a/setuptools/tests/test_virtualenv.py b/setuptools/tests/test_virtualenv.py
index eb8db7a6..a7f485a4 100644
--- a/setuptools/tests/test_virtualenv.py
+++ b/setuptools/tests/test_virtualenv.py
@@ -1,3 +1,4 @@
+import glob
 import os
 
 from pytest import yield_fixture
@@ -29,3 +30,21 @@ def test_clean_env_install(bare_virtualenv):
         'cd {source}',
         'python setup.py install',
     )).format(source=SOURCE_DIR))
+
+def test_pip_upgrade_from_source(virtualenv):
+    """
+    Check pip can upgrade setuptools from source.
+    """
+    dist_dir = virtualenv.workspace
+    # Generate source distribution / wheel.
+    virtualenv.run(' && '.join((
+        'cd {source}',
+        'python setup.py -q sdist -d {dist}',
+        'python setup.py -q bdist_wheel -d {dist}',
+    )).format(source=SOURCE_DIR, dist=dist_dir))
+    sdist = glob.glob(os.path.join(dist_dir, '*.zip'))[0]
+    wheel = glob.glob(os.path.join(dist_dir, '*.whl'))[0]
+    # Then update from wheel.
+    virtualenv.run('pip install ' + wheel)
+    # And finally try to upgrade from source.
+    virtualenv.run('pip install --no-cache-dir --upgrade ' + sdist)