Tests pass on windows

pre_commit/languages/python.py

@@ -1,6 +1,10 @@
 from __future__ import unicode_literals
 
 import contextlib
+import distutils.spawn
+import os
+
+import virtualenv
 
 from pre_commit.languages import helpers
 from pre_commit.util import clean_path_on_failure
@@ -12,7 +16,12 @@ ENVIRONMENT_DIR = 'py_env'
 class PythonEnv(helpers.Environment):
     @property
     def env_prefix(self):
-        return '. {{prefix}}{0}/bin/activate &&'.format(ENVIRONMENT_DIR)
+        return ". '{{prefix}}{0}activate' &&".format(
+            virtualenv.path_locations(
+                ENVIRONMENT_DIR,
+            )[-1].rstrip(os.sep) + os.sep,
+            'activate',
+        )
 
 
 @contextlib.contextmanager
@@ -20,6 +29,15 @@ def in_env(repo_cmd_runner):
     yield PythonEnv(repo_cmd_runner)
 
 
+def norm_version(version):
+    if os.name == 'nt':  # pragma: no cover (windows)
+        if not distutils.spawn.find_executable(version):
+            # The default place for python on windows is:
+            # C:\PythonXX\python.exe
+            version = r'C:\{0}\python.exe'.format(version.replace('.', ''))
+    return version
+
+
 def install_environment(repo_cmd_runner, version='default'):
     assert repo_cmd_runner.exists('setup.py')
 
@@ -27,10 +45,10 @@ def install_environment(repo_cmd_runner, version='default'):
     with clean_path_on_failure(repo_cmd_runner.path(ENVIRONMENT_DIR)):
         venv_cmd = ['virtualenv', '{{prefix}}{0}'.format(ENVIRONMENT_DIR)]
         if version != 'default':
-            venv_cmd.extend(['-p', version])
+            venv_cmd.extend(['-p', norm_version(version)])
         repo_cmd_runner.run(venv_cmd)
         with in_env(repo_cmd_runner) as env:
-            env.run('cd {prefix} && pip install .')
+            env.run("cd '{prefix}' && pip install .")
 
 
 def run_hook(repo_cmd_runner, hook, file_args):