[json] improve output to get leak_to and better logging.

recipe_modules/json/api.py

 # Copyright 2013 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.
 
 import functools
 import collections
 import contextlib
 import json
 
 from recipe_engine import recipe_api
 from recipe_engine import util as recipe_util
 from recipe_engine import config_types
 
 
 class JsonOutputPlaceholder(recipe_util.OutputPlaceholder):
   """JsonOutputPlaceholder is meant to be a placeholder object which, when added
   to a step's cmd list, will be replaced by annotated_run with the path to a
   temporary file (e.g. /tmp/tmp4lp1qM) which will exist only for the duration of

[tikuta1, 2017/03/14 09:55:31]

Better to update comment near here?

[iannucci, 2017/03/14 10:02:01]

Oh, wow, this comment is very out of date! I've fixed it.

   the step. If the script requires a flag (e.g. --output-json /path/to/file),
   you must supply that flag yourself in the cmd list.
 
   This placeholder can be optionally added when you use the Steps.step()
   method in this module.
 
   FIXME
   After the termination of the step, this file is expected to contain a valid
   JSON document, which will be set as the json.output for that step in the
   step_history OrderedDict passed to your recipe generator.
   """
-  def __init__(self, api, add_json_log, name=None):
-    self.raw = api.m.raw_io.output_text('.json')
+  def __init__(self, api, add_json_log, name=None, leak_to=None):
+    self.raw = api.m.raw_io.output_text('.json', leak_to=leak_to)
     self.add_json_log = add_json_log
     super(JsonOutputPlaceholder, self).__init__(name=name)
 
   @property
   def backing_file(self):
     return self.raw.backing_file
 
   def render(self, test):
     return self.raw.render(test)
 
   def result(self, presentation, test):
     raw_data = self.raw.result(presentation, test)
 
     valid = False
     ret = None
     try:
       ret = JsonApi.loads(
           raw_data, object_pairs_hook=collections.OrderedDict)
       valid = True
     # TypeError is raised when raw_data is None, which can happen if the json
     # file was not created. We then correctly handle this as invalid result.
     except (ValueError, TypeError):  # pragma: no cover
       pass
 
     if self.add_json_log:
-      key = self.label + ('' if valid else ' (invalid)')
-      with contextlib.closing(recipe_util.StringListIO()) as listio:
-        json.dump(ret, listio, indent=2, sort_keys=True)
-      presentation.logs[key] = listio.lines
+      if valid:
+        with contextlib.closing(recipe_util.StringListIO()) as listio:
+          json.dump(ret, listio, indent=2, sort_keys=True)
+        presentation.logs[self.label] = listio.lines
+      else:
+        presentation.logs[self.label + ' (invalid)'] = raw_data.splitlines()
 
     return ret
 
 
 class JsonApi(recipe_api.RecipeApi):
   def __init__(self, **kwargs):
     super(JsonApi, self).__init__(**kwargs)
     @functools.wraps(json.dumps)
     def dumps(*args, **kwargs):
       kwargs['sort_keys'] = True
@@ skipping 26 matching lines @@
       return True
     except Exception:
       return False
 
   @recipe_util.returns_placeholder
   def input(self, data):
     """A placeholder which will expand to a file path containing <data>."""
     return self.m.raw_io.input_text(self.dumps(data), '.json')
 
   @recipe_util.returns_placeholder
-  def output(self, add_json_log=True, name=None):
-    """A placeholder which will expand to '/tmp/file'."""
-    return JsonOutputPlaceholder(self, add_json_log, name=name)
+  def output(self, add_json_log=True, name=None, leak_to=None):
+    """A placeholder which will expand to '/tmp/file'.
+
+    If leak_to is provided, it must be a Path object. This path will be used in
+    place of a random temporary file, and the file will not be deleted at the
+    end of the step.
+    """
+    return JsonOutputPlaceholder(self, add_json_log, name=name, leak_to=leak_to)
 
   # TODO(you): This method should be in the `file` recipe_module
   def read(self, name, path, add_json_log=True, output_name=None, **kwargs):
     """Returns a step that reads a JSON file."""
     return self.m.python.inline(
         name,
         """
         import shutil
         import sys
         shutil.copy(sys.argv[1], sys.argv[2])
         """,
         args=[path,
               self.output(add_json_log=add_json_log, name=output_name)],
         add_python_log=False,
         **kwargs
     )