Make it possible to use 'cwd' in api.step.context

recipe_engine/recipe_api.py

 # Copyright 2016 The LUCI Authors. All rights reserved.
 # Use of this source code is governed under the Apache License, Version 2.0
 # that can be found in the LICENSE file.
 
 from __future__ import absolute_import
 import contextlib
 import keyword
 import re
 import types
 
@@ skipping 100 matching lines @@
         len(self.result.failures), len(self.result.all_results))
     msg += ', '.join((f.reason or f.name) for f in self.result.failures)
     return msg
 
   def __str__(self):  # pragma: no cover
     return "Aggregate Step Failure"
 
 
 _FUNCTION_REGISTRY = {
   'aggregated_result': {'combine': lambda a, b: b},
+  'cwd': {'combine': lambda a, b: b},

[Sergiy Byelozyorov, 2016/06/29 13:56:30]

This would always return value passed second and never return whatever is in the
compositor... what's the point?

[Paweł Hajdan Jr., 2016/06/29 13:57:57]

See other entries here which already do this. The meaning of that is to
override/overwrite value in compositor.

[Sergiy Byelozyorov, 2016/06/29 14:00:10]

But the point is that it doesn't... it just returns the second value without
ever considering the value in the compositor. And it does not update the value
in the compositor either:
https://cs.chromium.org/chromium/infra/recipes-py/recipe_engine/field_compose....

[Paweł Hajdan Jr., 2016/06/29 14:14:31]

While I have to provide a combine function here, I've simplified step recipe
module code based on your suggestion. PTAL.

   'env': {'combine': lambda a, b: dict(a, **b)},
   'name': {'combine': lambda a, b: '%s.%s' % (a, b)},
   'nest_level': {'combine': lambda a, b: a + b},
   'ran_step': {'combine': lambda a, b: b},
 }
 
 
 class AggregatedResult(object):
   """Holds the result of an aggregated run of steps.
 
@@ skipping 531 matching lines @@
     """
     Gets the BoundProperty version of this Property. Requires a name.
     """
     return BoundProperty(
         self._default, self.help, self.kind, name, property_type, module,
         self.param_name)
 
 class UndefinedPropertyException(TypeError):
   pass