V8 Buildbot: Pass isolate hashes from builder to tester.

scripts/slave/recipe_modules/v8/builders.py

Index: scripts/slave/recipe_modules/v8/builders.py
diff --git a/scripts/slave/recipe_modules/v8/builders.py b/scripts/slave/recipe_modules/v8/builders.py
index 25a643c11e5719874291ee4648ff9f3ba563000c..f6c6220fbc3da39722fda586d70ef7074270b309 100644
--- a/scripts/slave/recipe_modules/v8/builders.py
+++ b/scripts/slave/recipe_modules/v8/builders.py
@@ -41,7 +41,10 @@ BUILDERS = {
         'bot_type': 'builder',
         'build_gs_archive': 'linux_swarming_staging_archive',
         'enable_swarming': True,
-        'testing': {'platform': 'linux'},
+        'testing': {
+          'platform': 'linux',
+          'isolated_tests': {'default': '[dummy hash for default]'},

[kjellander_chromium, 2015/10/09 08:05:03]

This looks like test data to me, should it really be here?
Or is it because you use old-style triggering?

I don't see any of the builders in
scripts/slave/recipe_modules/chromium_tests/chromium_linux.py do this...
It seems the testers call find_isolated_tests instead, after extracting the
build.

[Paweł Hajdan Jr., 2015/10/09 08:22:09]

FWIW I'm fine with this. Alternatively, maybe I didn't understand your concern,
Henrik.
find_isolated_tests has its drawbacks as well (e.g. too much magic when it scans
the tree as opposed to being explicit about which isolated targets we want - I
actually prefer the latter, which seems to be done in this CL).

[Michael Achenbach, 2015/10/09 08:25:00]

I'd like to do this smarter. Right now, there is logic in the builder that scans
the tests to be run on the testers in order to calculate what to isolate. I
should reuse the same logic to simulate what was isolated in the tests. Will do
that in some follow up, otherwise I'd have to guess correctly for each builder
what it should simulate.

+        },
         'triggers': [
           'V8 Linux - swarming staging',
         ],