User defined TEST_UNDECLARED_OUTPUT_DIR

[jxramos]

Presently bazel is the one that sets the value for this output directory TEST_UNDECLARED_OUTPUT_DIR. Our team authors some HIL tests that need to funnel all their outputs into a docker mounted folder to persist outside the docker session. How would the bazel community feel about exposing this variable to be modifiable by the user to some arbitrary path via a cli?

similar to how we have
--test_output=streamed

we could have something going like
--test_output_dir=$(pwd)/data_for_test
--test_output_dir=/projX/data_for_test

and then at runtime
TEST_UNDECLARED_OUTPUT_DIR=/projX/data_for_test

[jxramos]

Adding some context, the user would be responsible here for managing artifact overwrites and name collisions and all that sort of regular directory management and responsibilities they'd assume should they reuse the same --test_output_dir value across separate bazel test sessions.