Bazel test produces misleading error on missing stdout

[ola-rozenfeld]

When the hello_world test is run with remote execution, and the remote execution produces a result that does not contain the expected stdout_digest, Bazel produces a very non-intuitive error:

ERROR: Caught I/O exception: java.io.FileNotFoundException: /usr/local/google/home/yiyu/.cache/bazel/_bazel_yiyu/f747e05abb9ae5ddb2b2bcbf4efc8838/execroot/main/bazel-out/linux_gnu_x86-fastbuild/testlogs/hello-world_test/test.log (No such file or directory)

I think this is because Bazel tries and fails to create a test.log file, because the output is missing.

To reproduce: run with remote execution on:

cc_test(
name = "hello-world_test",
srcs = ["hello-world.cc"],
)

hello-world.cc:

#include

int main(int argc, char** argv) {
std::cout << "Hello, world!" << std::endl;
return 0;
}

and hack the remote worker to return an ActionResult with the correct test.xml, but no stdout.

See b/67038484 internally for more context.

[ola-rozenfeld]

Update: I have a patch for this in review internally.