Fix handling of empty .analysis_options files and test this case

Fix handling of empty .analysis_options files and test this case

Fixes #24431

R=brianwilkerson@google.com

Committed: https://github.com/dart-lang/sdk/commit/9535715f928a70987d7a164b56b2e65e0ffb581e

[Cutch, 2015-09-24 19:21:56]

johnmccutchan@google.com changed reviewers:
+ brianwilkerson@google.com, pquitslund@google.com

[pquitslund, 2015-09-24 19:26:18]

https://codereview.chromium.org/1369573003/diff/1/pkg/analyzer/lib/source/ana...
File pkg/analyzer/lib/source/analysis_options_provider.dart (left):

https://codereview.chromium.org/1369573003/diff/1/pkg/analyzer/lib/source/ana...
pkg/analyzer/lib/source/analysis_options_provider.dart:38: if (doc is! YamlMap)
{
I would prefer:

  if (doc != null && doc is! YamlMap)

It's still handy to identify poorly formatted options files.

[Brian Wilkerson, 2015-09-24 19:26:20]

LGTM

[pquitslund, 2015-09-24 19:27:41]

On 2015/09/24 19:26:18, pquitslund wrote:
>
https://codereview.chromium.org/1369573003/diff/1/pkg/analyzer/lib/source/ana...
> File pkg/analyzer/lib/source/analysis_options_provider.dart (left):
> 
>
https://codereview.chromium.org/1369573003/diff/1/pkg/analyzer/lib/source/ana...
> pkg/analyzer/lib/source/analysis_options_provider.dart:38: if (doc is!
YamlMap)
> {
> I would prefer:
> 
>   if (doc != null && doc is! YamlMap)
> 
> It's still handy to identify poorly formatted options files.

The rub though is that an EMPTY file shouldn't trigger an exception (and so the
doc != null check).

[Cutch, 2015-09-24 19:37:22]

https://codereview.chromium.org/1369573003/diff/1/pkg/analyzer/lib/source/ana...
File pkg/analyzer/lib/source/analysis_options_provider.dart (left):

https://codereview.chromium.org/1369573003/diff/1/pkg/analyzer/lib/source/ana...
pkg/analyzer/lib/source/analysis_options_provider.dart:38: if (doc is! YamlMap)
{
On 2015/09/24 19:26:17, pquitslund wrote:
> I would prefer:
> 
>   if (doc != null && doc is! YamlMap)
> 
> It's still handy to identify poorly formatted options files.

Done and I've added a test for the invalid yaml case.

[Cutch, 2015-09-24 19:38:57]

Committed patchset #2 (id:20001) manually as
9535715f928a70987d7a164b56b2e65e0ffb581e (presubmit successful).

[pquitslund, 2015-09-24 20:47:21]

Awesome.  Thanks  John!