Dump empty json to output when no shard json file is given.

Dump empty json to output when no shard json file is given.

Previously when test results presentation does not receive any json
input file, the script will raise a parser error. This is confusing to
developer, because they may mistake the parser error in this script as
the cause of the crash, instead of the reason why no json input file is
given at the first place.

In this cl, test results presentation will not raise error anymore when
no json file is given.

BUG=715972
Review-Url: https://codereview.chromium.org/2845973004
Cr-Commit-Position: refs/heads/master@{#467834}
Committed: https://chromium.googlesource.com/chromium/src/+/043d55636176cf1c5f9b0ff29c9c853bb538dbd5

[BigBossZhiling, 2017-04-27 18:33:39]

hzl@google.com changed reviewers:
+ jbudorick@chromium.org

[jbudorick, 2017-04-27 18:40:37]

https://codereview.chromium.org/2845973004/diff/20001/build/android/pylib/res...
File build/android/pylib/results/presentation/test_results_presentation.py
(right):

https://codereview.chromium.org/2845973004/diff/20001/build/android/pylib/res...
build/android/pylib/results/presentation/test_results_presentation.py:359: if
args.json_file:
Given that you're handling the two cases differently, this might be a bit more
readable if we just split it into two conditions at the top level, e.g.

  if len(args.positional) == 0 and args.json_file is None:
    if args.output_json:
      ...
  elif len(args.positional) != 0 and args.json_file:
    raise parser.error(...)

https://codereview.chromium.org/2845973004/diff/20001/build/android/pylib/res...
build/android/pylib/results/presentation/test_results_presentation.py:365:
f.write('{}')
nit: json.dump({}, f)

I know the result is the same, but I think it's a bit more clear.

[BigBossZhiling, 2017-04-27 20:41:49]

https://codereview.chromium.org/2845973004/diff/20001/build/android/pylib/res...
File build/android/pylib/results/presentation/test_results_presentation.py
(right):

https://codereview.chromium.org/2845973004/diff/20001/build/android/pylib/res...
build/android/pylib/results/presentation/test_results_presentation.py:359: if
args.json_file:
On 2017/04/27 18:40:37, jbudorick wrote:
> Given that you're handling the two cases differently, this might be a bit more
> readable if we just split it into two conditions at the top level, e.g.
> 
>   if len(args.positional) == 0 and args.json_file is None:
>     if args.output_json:
>       ...
>   elif len(args.positional) != 0 and args.json_file:
>     raise parser.error(...)

Done.

https://codereview.chromium.org/2845973004/diff/20001/build/android/pylib/res...
build/android/pylib/results/presentation/test_results_presentation.py:365:
f.write('{}')
On 2017/04/27 18:40:37, jbudorick wrote:
> nit: json.dump({}, f)
> 
> I know the result is the same, but I think it's a bit more clear.

Done.

[BigBossZhiling, 2017-04-27 20:41:49]

https://codereview.chromium.org/2845973004/diff/20001/build/android/pylib/res...
File build/android/pylib/results/presentation/test_results_presentation.py
(right):

https://codereview.chromium.org/2845973004/diff/20001/build/android/pylib/res...
build/android/pylib/results/presentation/test_results_presentation.py:359: if
args.json_file:
On 2017/04/27 18:40:37, jbudorick wrote:
> Given that you're handling the two cases differently, this might be a bit more
> readable if we just split it into two conditions at the top level, e.g.
> 
>   if len(args.positional) == 0 and args.json_file is None:
>     if args.output_json:
>       ...
>   elif len(args.positional) != 0 and args.json_file:
>     raise parser.error(...)

Done.

https://codereview.chromium.org/2845973004/diff/20001/build/android/pylib/res...
build/android/pylib/results/presentation/test_results_presentation.py:365:
f.write('{}')
On 2017/04/27 18:40:37, jbudorick wrote:
> nit: json.dump({}, f)
> 
> I know the result is the same, but I think it's a bit more clear.

Done.

[jbudorick, 2017-04-27 21:57:31]

lgtm

[BigBossZhiling, 2017-04-27 22:23:08]

The CQ bit was checked by hzl@google.com

[commit-bot: I haz the power, 2017-04-27 22:29:44]

CQ is trying da patch.

Follow status at:
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-04-28 02:08:12]

CQ is committing da patch.

Bot data: {"patchset_id": 40001, "attempt_start_ts": 1493331788658790,
"parent_rev": "b539fa1123a19e6499f58582da55ca5af9df94a4", "commit_rev":
"043d55636176cf1c5f9b0ff29c9c853bb538dbd5"}

[commit-bot: I haz the power, 2017-04-28 02:08:22]

Description was changed from

==========
Dump empty json to output when no shard json file is given.

Previously when test results presentation does not receive any json
input file, the script will raise a parser error. This is confusing to
developer, because they may mistake the parser error in this script as
the cause of the crash, instead of the reason why no json input file is
given at the first place.

In this cl, test results presentation will not raise error anymore when
no json file is given.

BUG=715972
==========

to

==========
Dump empty json to output when no shard json file is given.

Previously when test results presentation does not receive any json
input file, the script will raise a parser error. This is confusing to
developer, because they may mistake the parser error in this script as
the cause of the crash, instead of the reason why no json input file is
given at the first place.

In this cl, test results presentation will not raise error anymore when
no json file is given.

BUG=715972

Review-Url: https://codereview.chromium.org/2845973004
Cr-Commit-Position: refs/heads/master@{#467834}
Committed:
https://chromium.googlesource.com/chromium/src/+/043d55636176cf1c5f9b0ff29c9c...
==========

[commit-bot: I haz the power, 2017-04-28 02:08:23]

Committed patchset #3 (id:40001) as
https://chromium.googlesource.com/chromium/src/+/043d55636176cf1c5f9b0ff29c9c...