[ benchmark ] unable to use the json reporter about vitest HOT 2 OPEN

It looks like the documentation of benchmark.outputFile is a little outdated. For comparison, you need to use benchmark.outputJson and benchmark.compare combo as shown in https://vitest.dev/config/#benchmark-outputJson

# save main branch's result
git checkout main
vitest bench --outputJson main.json

# change a branch and compare against main
git checkout feature
vitest bench --compare main.json

Technically, you can put a same file to both options like below, but this will always overwrite bench.json, so that's a bit different from the intended usage.

export default defineConfig({
  test: {
    benchmark: {
      outputJson: './bench.json',
      compare: './bench.json'
    },
  },
});

from vitest.

Thanks @hi-ogawa this works with a small gotcha

It will fail at the first runtime if there's no bench.json file present. might be worth adding this detail to the docs too

I updated the Stackblitz link to reflect this
thanks a bunch !

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