It seems that --single-process-tests is not an option of Gtest, it's implemented in Chromium code: https://cs.chromium.org/chromium/src/base/test/launcher/unit_test_launcher.cc?q=single-process-tests&sq=package:chromium&l=53&dr=C

As a hacky workaround, I can list all the tests, split them into N --gtest_filter= lists, and run it N times with --single-process-tests flag. I don't really want to do that, so keep thinking and looking into the tests launcher code.

I think sharding is already baked into the binary, maybe 

  --test-launcher-total-shards=N
    Sets the total number of shards to N.

is used for that?

btw, you mentioned that running unit_tests with --single-process-tests flag crashes, even if the tests are split into N shards, each individual shard is still using --single-process-tests, how can it help with the crash?

If I ever have to do stuff proposed in c#3, I should probably do it in the launcher: https://cs.chromium.org/chromium/src/base/test/launcher/test_launcher.cc?rcl=01e526376476bf02c445e992ac7a9359f4482b29&l=917

Yuke, I tried --test-launcher-total-shards=N and it doesn't help. For example:

$ python testing/xvfb.py out/coverage/unit_tests --test-launcher-total-shards=2 --test-launcher-jobs=1 --gtest_filter=*WithIncidentIgnoreBypass/PreferenceValidationDelegateWithIncident*

There are 24 tests from 4 testcases that match the filter I specified. As a result, there always are 4 coverage dumps unless I use --single-process-tests flag.

>> btw, you mentioned that running unit_tests with --single-process-tests flag crashes, even if the tests are split into N shards, each individual shard is still using --single-process-tests, how can it help with the crash?


Let me try that, launched with 200 shards and --single-process-tests.

Nope, still crashes.

Right, looks like the binary ignores --test-launcher-total-shards flag, as in the output "Using sharding settings from environment. This is shard 0/1", but given that each individual shard needs to use --single-process-tests anyway, I guess this won't help.

liaoyuke@liaoyuke-macpro src (master) $ ./out/Coverage/url_unittests --test-launcher-total-shards=5
IMPORTANT DEBUGGING NOTE: batches of tests are run inside their
own process. For debugging a test inside a debugger, use the
--gtest_filter=<your_test_name> flag along with
--single-process-tests.
Using sharding settings from environment. This is shard 0/1
Using 24 parallel jobs.

Yes :( Even running in a single process could be OK, but I' always have some CHECK's failing or null deref crashes, so that process cannot finish successfully.

The idea proposed here wouldn't work for us anyway, WontFix'ing this. Let's continue discussion in  issue 789733 .