Clean up how the environments work.

pre_commit/languages/node.py

@@ -8,37 +8,42 @@ from pre_commit.languages import python
 NODE_ENV = 'node_env'
 
 
-class NodeEnv(object):
-    def __init__(self, py_env):
-        self.py_env = py_env
-        self.env_prefix = '. {0}/bin/activate &&'.format(NODE_ENV)
-
-    def run(self, cmd, **kwargs):
-        return self.py_env.run(' '.join([self.env_prefix, cmd]), **kwargs)
+class NodeEnv(python.PythonEnv):
+    @property
+    def env_prefix(self):
+        base = super(NodeEnv, self).env_prefix
+        return ' '.join([base, '. {0}/bin/activate &&'.format(NODE_ENV)])
 
 
 @contextlib.contextmanager
-def in_env(py_env):
-    yield NodeEnv(py_env)
+def in_env():
+    yield NodeEnv()
 
 
 def install_environment():
     assert local.path('package.json').exists()
 
-    if local.path('node_env').exists():
+    if local.path(NODE_ENV).exists():
         return
 
     local['virtualenv'][python.PY_ENV]()
 
     with python.in_env() as python_env:
         python_env.run('pip install nodeenv')
-        python_env.run('nodeenv --jobs 4 {0}'.format(NODE_ENV))
 
-        with in_env(python_env) as node_env:
+        try:
+            # Try and use the system level node executable first
+            python_env.run('nodeenv -n system {0}'.format(NODE_ENV))
+        except Exception:
+            # TODO: log exception here
+            # cleanup
+            local.path(NODE_ENV).remove()
+            python_env.run('nodeenv --jobs 4 {0}'.format(NODE_ENV))
+
+        with in_env() as node_env:
             node_env.run('npm install -g')
 
 
 def run_hook(hook, file_args):
-    with python.in_env() as py_env:
-        with in_env(py_env) as node_env:
-            return helpers.run_hook(node_env, hook, file_args)
+    with in_env() as node_env:
+        return helpers.run_hook(node_env, hook, file_args)