Fails with "Instrumentation tests require a valid test-runner-class defined." after upgrading to v21.01.0

[kubode]

Describe the bug

A clear and concise description of what the bug is.

I got Instrumentation tests require a valid test-runner-class defined. error when I run flank run android after upgrading to v21.01.0:

The documentation says:

  ### Instrumentation Test Runner Class
  ## The fully-qualified Java class name of the instrumentation test runner
  ## (default: the last name extracted from the APK manifest).
  # test-runner-class: com.foo.TestRunner

test-runner-class is not required but, I got the error.
Is the documentation is wrong?

To Reproduce

Steps to reproduce the behavior:

1. Set gcloud.type: instrumentation to your flank.yml.
2. Run flank run android.
3. Flank exits with Instrumentation tests require a valid test-runner-class defined. error.

Expected behavior

A clear and concise description of what you expected to happen.

No errors.

Details (please complete the following information):

Have you tested on the latest Flank snapshot?

Post the output of flank --version.

version: v21.01.0
revision: 66cff410ff585beffba5f150799b3f77b7065dfb

My flank.yml:

gcloud:
  type: instrumentation
  app: # [REDACTED]
  test: # [REDACTED]
  device:
    - model: walleye
      version: 28
      locale: en_US
      orientation: portrait
  environment-variables:
    timeout_msec: 20000
    coverage: true
    coverageFile: /sdcard/coverage.ec
    clearPackageData: true
  use-orchestrator: false
  directories-to-pull:
    - /sdcard/
  timeout: 10m

flank:
  max-test-shards: 8
  shard-time: 50
  smart-flank-gcs-path: # [REDACTED]
  test-targets-always-run:
    - class # [REDACTED]
  files-to-download:
    - .*/sdcard/[^/]+\.ec$

Additional context

Add any other context about the problem here.

This issue did not happen with v20.09.3.
Seems like this issue was included at #1230.

[pawelpasterz]

@kubode
Thanks for reporting it! Try without type: instrumentation (just remove/comment in config file). Yet, it's a workaround and needs to be fixed :)