Truncate or warn about long virtualenv paths (#12)

appveyor.yml

@@ -64,11 +64,11 @@ install:
   # target Python version and architecture
   - "pip install wheel"
 
-init:
-  - ps: iex ((new-object net.webclient).DownloadString('https://raw.githubusercontent.com/appveyor/ci/master/scripts/enable-rdp.ps1'))
+# init:
+#   - ps: iex ((new-object net.webclient).DownloadString('https://raw.githubusercontent.com/appveyor/ci/master/scripts/enable-rdp.ps1'))
 
-on_finish:
-  - ps: $blockRdp = $true; iex ((new-object net.webclient).DownloadString('https://raw.githubusercontent.com/appveyor/ci/master/scripts/enable-rdp.ps1'))
+# on_finish:
+#   - ps: $blockRdp = $true; iex ((new-object net.webclient).DownloadString('https://raw.githubusercontent.com/appveyor/ci/master/scripts/enable-rdp.ps1'))
 
 build_script:
   - "pip install ."

nox/session.py

@@ -12,6 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import hashlib
 import os
 import re
 import unicodedata
@@ -24,17 +25,31 @@
 import six
 
 
-def _normalize_path(path):
-    """Normalizes a string to be a "safe" filesystem path."""
+def _normalize_path(envdir, path):
+    """Normalizes a string to be a "safe" filesystem path for a virtualenv."""
     if isinstance(path, six.binary_type):
         path = path.decode('utf-8')
 
     path = unicodedata.normalize('NFKD', path).encode('ascii', 'ignore')
     path = path.decode('ascii')
     path = re.sub('[^\w\s-]', '-', path).strip().lower()
     path = re.sub('[-\s]+', '-', path)
-    path = path.strip('-')[:255]
-    return path
+    path = path.strip('-')
+
+    full_path = os.path.join(envdir, path)
+    if len(full_path) > 128 - len('bin/pythonX.Y'):
+        if len(envdir) < 128 - 9:
+            path = hashlib.sha1(path.encode('ascii')).hexdigest()[:8]
+            full_path = os.path.join(envdir, path)
+            logger.warning(
+                'The virtualenv name was hashed to avoid being too long.')
+        else:
+            logger.error(
+                'The virtualenv path {} is too long and will cause issues on '
+                'some environments. Use the --envdir path to modify where '
+                'nox stores virtualenvs.'.format(full_path))
+
+    return full_path
 
 
 class _SessionQuit(Exception):
@@ -175,9 +190,8 @@ def _create_venv(self):
             return
 
         self.venv = VirtualEnv(
-            os.path.join(
-                self.global_config.envdir,
-                _normalize_path(self.signature or self.name)),
+            _normalize_path(
+                self.global_config.envdir, self.signature or self.name),
             interpreter=self.config.interpreter,
             reuse_existing=(
                 self.config.reuse_existing_virtualenv or

tests/test_session.py

@@ -24,14 +24,31 @@
 
 
 def test__normalize_path():
-    assert nox.session._normalize_path(u'hello') == 'hello'
-    assert nox.session._normalize_path(b'hello') == 'hello'
-    assert nox.session._normalize_path('hello(world)') == 'hello-world'
+    envdir = 'envdir'
+    assert nox.session._normalize_path(envdir, u'hello') == 'envdir/hello'
+    assert nox.session._normalize_path(envdir, b'hello') == 'envdir/hello'
     assert nox.session._normalize_path(
-        'hello(world, meep)') == 'hello-world-meep'
+        envdir, 'hello(world)') == 'envdir/hello-world'
     assert nox.session._normalize_path(
-        'tests(interpreter="python2.7", django="1.10")') == (
-        'tests-interpreter-python2-7-django-1-10')
+        envdir, 'hello(world, meep)') == 'envdir/hello-world-meep'
+    assert nox.session._normalize_path(
+        envdir, 'tests(interpreter="python2.7", django="1.10")') == (
+        'envdir/tests-interpreter-python2-7-django-1-10')
+
+
+def test__normalize_path_hash():
+    envdir = 'd' * (128 - len('bin/pythonX.Y') - 10)
+    norm_path = nox.session._normalize_path(
+        envdir, 'a-really-long-virtualenv-path')
+    assert 'a-really-long-virtualenv-path' not in norm_path
+    assert len(norm_path) < 128
+
+
+def test__normalize_path_give_up():
+    envdir = 'd' * 128
+    norm_path = nox.session._normalize_path(
+        envdir, 'any-path')
+    assert 'any-path' in norm_path
 
 
 @pytest.fixture