Avoid exceptions when analyzing truncated test output.

Avoid exceptions when analyzing truncated test output.

r34867 introduced a mechanism to truncate excessively long test
output.  Since the truncation may happen in the middle of a line, we
need to be tolerant of mal-formed lines when analyzing the test
output.

R=kustermann@google.com, whesse@google.com

Committed: https://code.google.com/p/dart/source/detail?r=35063

[Paul Berry, 2014-04-14 17:28:44]

whesse: this fixes the unhandled exception I emailed you about on 9 Apr.

[Bill Hesse, 2014-04-15 07:27:44]

LGTM.  Do you think we should be doing something to either:

1) Avoid truncating lines, if they aren't extremely long
or
2) Look for ERROR, PASS, etc. in what we truncate.

Both of these would be more complicated than what we have now.

[kustermann, 2014-04-15 07:43:30]

LGTM

Are we actually hitting this with the dartanalyzer?

[Do we need to increae the amount of data we keep?]

[Paul Berry, 2014-04-15 15:49:39]

Committed patchset #1 manually as r35063 (presubmit successful).

[Paul Berry, 2014-04-15 16:56:18]

On 2014/04/15 07:43:30, kustermann wrote:
> LGTM
> 
> Are we actually hitting this with the dartanalyzer?
> 
> [Do we need to increae the amount of data we keep?]

My dev machine hits this with
generated_tests/language/function_syntax_test_67.dart.  Running the test
manually it looks like a case of really poor error recovery in the analyzer (the
analyzer reports 685 errors/warnings).

IMHO there's no reason to increase the amount of data we keep--we should just
fix the analyzer to recover from errors better so that this doesn't happen. 
I've filed https://code.google.com/p/dart/issues/detail?id=18244 to remind
myself (or one of the other editor folks) to work on that.

In fact, I'm tempted to suggest that "output truncated" be considered a new
Expectation type, so that if it occurs we'll notice it as a test failure, and
then we can mark it in a .status file.  However, that's complicated because the
output contains many copies of the absolute path of the .dart file being
analyzed, so output truncation is going to vary from one user/machine to the
next (this explains why the problem I experienced didn't show up on the
buildbot).