bazel coverage: "Coverage runner: cannot locate file"

[ensonic]

Description of the problem / feature request:

Generating a test coverage report fails with the error above. It looks like this is the code
https://github.com/bazelbuild/bazel/blob/master/tools/test/collect_coverage.sh#L68
and LCOV_MERGER is empty. Running bazel coverage --combined_report=lcov //... does not help, since it leads to #6450.

Bugs: what's the simplest, easiest way to reproduce this bug? Please provide a minimal example if possible.

git clone https://github.com/googlecloudrobotics/core.git
cd core
bazel coverage //...

What operating system are you running Bazel on?

linux (debian)

What's the output of bazel info release?

release 0.22.0

Have you found anything relevant by searching the web?

Nothing on Stackoverflow/Github issues.

[ensonic]

Is something failing to pass the LcovMerger to the env? It looks like this was added here:
werkt@b00c8e7

[iirina]

@ensonic what rule sets do you use? Only the rules embedded by Bazel and that allow coverage collection (Java, C++, shell) have an attribute defined named $lcov_merger. For custom rules the owners have to also define this attribute.

[ensonic]

I just run it against the top of the project, so there is at least python and go. I understand that coverage report is not 100%, but it would be nice to find a better failure mode (eg not run the test rule if the attr is missing?).

[sgowroji]

Hi there! We're doing a clean up of old issues and will be closing this one. Please reopen if you’d like to discuss anything further. We’ll respond as soon as we have the bandwidth/resources to do so.