How can I ask Bazel to rerun a cached test?

Ittai picture Ittai · Jun 25, 2017 · Viewed 17.6k times · Source

I'm trying to analyze and fix a flaky test which is often green.
My problem is that once the test passes Bazel doesn't re-run it until any of the inputs have changed.
I saw you can ask Bazel to re-run a target but AFAICT it's only until the first time it's green (i.e. to mitigate a flaky test and not solve it).

Is there a way to ask Bazel to run the test even if it passed?
I'd like something like bazel test --force-attempts=50 //my-package:my-target

Answer

Ittai picture Ittai · Jun 25, 2017

There's a flag for it

--cache_test_results=(yes|no|auto) (-t)

If this option is set to 'auto' (the default) then Bazel will only rerun a test if any of the following conditions applies:

  • Bazel detects changes in the test or its dependencies
  • the test is marked as external
  • multiple test runs were requested with --runs_per_test the test failed. If 'no', all tests will be executed unconditionally.

If 'yes', the caching behavior will be the same as auto except that it may cache test failures and test runs with --runs_per_test.

Note that test results are always saved in Bazel's output tree, regardless of whether this option is enabled, so you needn't have used --cache_test_results on the prior run(s) of bazel test in order to get cache hits. The option only affects whether Bazel will use previously saved results, not whether it will save results of the current run.

Users who have enabled this option by default in their .bazelrc file may find the abbreviations -t (on) or -t- (off) convenient for overriding the default on a particular run.

https://docs.bazel.build/versions/master/user-manual.html#flag--cache_test_results