Merge remote-tracking branch 'origin/master' into performance_test

Conflicts:
	pre_commit/languages/python.py

pre_commit/languages/node.py

@@ -1,7 +1,44 @@
+import contextlib
+from plumbum import local
+
+from pre_commit.languages import helpers
+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)
+
+
+@contextlib.contextmanager
+def in_env(py_env):
+    yield NodeEnv(py_env)
+
 
 def install_environment():
-    raise NotImplementedError
+    assert local.path('package.json').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 {0}'.format(NODE_ENV))
+
+        with in_env(python_env) as node_env:
+            node_env.run('npm install -g')
 
 
 def run_hook(hook, file_args):
-    raise NotImplementedError
+    with python.in_env() as py_env:
+        with in_env(py_env) as node_env:
+            return helpers.run_hook(node_env, hook, file_args)