Allow base path overrides when running a recipe.

recipe_modules/path/config.py

 # Copyright 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 from recipe_engine.config import config_item_context, ConfigGroup, Dict, Static
 from recipe_engine.config_types import Path
+from recipe_engine.types import FrozenDict
 
-def BaseConfig(CURRENT_WORKING_DIR, TEMP_DIR, **_kwargs):
+def BaseConfig(CURRENT_WORKING_DIR, TEMP_DIR, BASE_PATH_OVERRIDES, **_kwargs):
   assert CURRENT_WORKING_DIR[0].endswith(('\\', '/'))
   assert TEMP_DIR[0].endswith(('\\', '/'))
   return ConfigGroup(
     # base path name -> [tokenized absolute path]
     base_paths    = Dict(value_type=tuple),
 
     # dynamic path name -> Path object (referencing one of the base_paths)
     dynamic_paths = Dict(value_type=(Path, type(None))),
 
     CURRENT_WORKING_DIR = Static(tuple(CURRENT_WORKING_DIR)),
     TEMP_DIR = Static(tuple(TEMP_DIR)),
+    BASE_PATH_OVERRIDES = Static(FrozenDict(BASE_PATH_OVERRIDES)),
   )
 
 def test_name(args):  # pragma: no cover
   if args['CURRENT_WORKING_DIR'][0] == '/':
     return 'posix'
   else:
     return 'windows'
 
 config_ctx = config_item_context(BaseConfig)
 
 @config_ctx(is_root=True)
 def BASE(c):
   c.base_paths['cwd'] = c.CURRENT_WORKING_DIR
   c.base_paths['tmp_base'] = c.TEMP_DIR
+  for k, v in c.BASE_PATH_OVERRIDES.iteritems():
+    c.base_paths[k] = v  # pragma: no cover
 
 @config_ctx()
 def buildbot(c):
-  c.base_paths['root'] = c.CURRENT_WORKING_DIR[:-4]
-  c.base_paths['slave_build'] = c.CURRENT_WORKING_DIR
+  c.base_paths.setdefault('root', c.CURRENT_WORKING_DIR[:-4])
+  c.base_paths.setdefault('slave_build', c.CURRENT_WORKING_DIR)
   for token in ('build_internal', 'build', 'depot_tools'):
-    c.base_paths[token] = c.base_paths['root'] + (token,)
+    c.base_paths.setdefault(token, c.base_paths['root'] + (token,))
   c.dynamic_paths['checkout'] = None
 
 @config_ctx()
 def example(c):
-  c.base_paths['slave_build'] = c.CURRENT_WORKING_DIR
+  c.base_paths.setdefault('slave_build', c.CURRENT_WORKING_DIR)
   c.dynamic_paths['borts'] = None
 
 @config_ctx(includes=['buildbot'])
 def swarming(c):
-  c.base_paths['slave_build'] = (
+  c.base_paths.setdefault('slave_build', (

[martiniss, 2016/01/19 23:29:37]

This won't work as is.... base_paths already has a value for slave_build, so
this won't change it. Should just assign here.

       c.CURRENT_WORKING_DIR[:1] +
-      ('b', 'fake_build', 'slave', 'fake_slave', 'build'))
+      ('b', 'fake_build', 'slave', 'fake_slave', 'build')))