Rstest Debugging Workflow

Use this skill when Rstest is slower than expected, slower than Jest or Vitest, slower than a previous Rstest baseline, or when users report that tests spend a long time before starting.

The goal is not to guess a root cause from config names alone. First identify where time is being spent, then change one variable at a time and compare the result.

1. Establish a reproducible baseline

Before changing config or code:

• Pick the narrowest representative command. Prefer a single file, package, or fixture over the whole workspace.
• Record the exact command, working directory, test environment (node, jsdom, happy-dom, browser mode), and relevant worker settings.
• Measure at least one cold run and one warm run with the same command.
• Do not change multiple config fields before the first measurement.

Common baseline commands: