Added path function to PrefixedCommandRunner

pre_commit/prefixed_command_runner.py

@@ -33,10 +33,13 @@ class PrefixedCommandRunner(object):
 
         return proc.returncode, stdout, stderr
 
+    def path(self, path_end):
+        path = os.path.join(self.prefix_dir, path_end)
+        return os.path.normpath(path)
+
     @classmethod
-    def from_command_runner(cls, command_runner, prefix_postfix):
+    def from_command_runner(cls, command_runner, path_end):
         """Constructs a new command runner from an existing one by appending
-        `prefix_postfix` to the command runner's prefix directory.
+        `path_end` to the command runner's prefix directory.
         """
-        new_prefix = os.path.join(command_runner.prefix_dir, prefix_postfix)
-        return cls(new_prefix, popen=command_runner.__popen)
+        return cls(command_runner.path(path_end), popen=command_runner.__popen)

pre_commit/runner.py

@@ -5,6 +5,7 @@ import os.path
 import pre_commit.constants as C
 from pre_commit import git
 from pre_commit.clientlib.validate_config import load_config
+from pre_commit.prefixed_command_runner import PrefixedCommandRunner
 from pre_commit.repository import Repository
 from pre_commit.util import cached_property
 
@@ -44,3 +45,7 @@ class Runner(object):
     @cached_property
     def pre_commit_path(self):
         return os.path.join(self.git_root, '.git/hooks/pre-commit')
+
+    @cached_property
+    def workspace_runner(self):
+        return PrefixedCommandRunner(C.HOOKS_WORKSPACE)