top level `bench` prints result twice

[marcalexiei]

Describe the bug

When bench is invoked at the top of the module his results are displayed twice.

Wrapping the bench call in a describe doesn't duplicate the results.

sum-without-describe.bench.ts

import { bench } from "vitest";

bench("sum", () => {
  1 + 1;
});

sum-with-describe.bench.ts

import { bench, describe } from "vitest";

describe("sum", () => {
  bench("a", () => {
    1 + 1;
  });
});

Result

 ✓ tests/sum-with-describe.bench.ts > sum 5789ms
     name             hz     min     max    mean     p75     p99    p995    p999     rme   samples
   · a     48,128,806.17  0.0000  0.0327  0.0000  0.0000  0.0000  0.0000  0.0001  ±0.05%  24064404

 ✓ tests/sum-without-describe.bench.ts 5748ms
     name             hz     min     max    mean     p75     p99    p995    p999     rme   samples
   · sum   48,075,917.04  0.0000  0.0334  0.0000  0.0000  0.0000  0.0000  0.0001  ±0.05%  24037959

 ✓ tests/sum-without-describe.bench.ts 5748ms
     name             hz     min     max    mean     p75     p99    p995    p999     rme   samples
   · sum   48,075,917.04  0.0000  0.0334  0.0000  0.0000  0.0000  0.0000  0.0001  ±0.05%  24037959

Reproduction

Code: https://github.com/marcalexiei/vitest-bench-playground
GitHub actions: https://github.com/marcalexiei/vitest-bench-playground/actions/runs/22277251116/job/64441360076

System Info

System:
    OS: macOS 26.3
    CPU: (8) arm64 Apple M3
    Memory: 139.19 MB / 16.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 24.12.0 - /.nvm/versions/node/v24.12.0/bin/node
    npm: 11.6.2 - /.nvm/versions/node/v24.12.0/bin/npm
    pnpm: 10.28.2 - /.nvm/versions/node/v24.12.0/bin/pnpm
  Browsers:
    Chrome: 144.0.7559.133
    Safari: 26.3
  npmPackages:
    vitest: 4.0.18 => 4.0.18

Used Package Manager

pnpm

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[idirdev]

Can reproduce this. When a bench() call sits at the top level of the module (not inside a describe block), the results get printed twice. Wrapping it in describe fixes it.

Looking at how Vitest handles benchmarks, top-level bench() calls get implicitly grouped into a default suite. I think the reporter is receiving the result event both for the individual bench task and for the implicit suite, and printing the table for each one.

Both lines in the output are identical (same hz, same samples, same timing), so the benchmark only runs once. It's purely a display thing.

Workaround is simple, just wrap your benchmarks:

import { bench, describe } from "vitest";

describe("math", () => {
  bench("sum", () => {
    1 + 1;
  });
});

Not great for quick one-off benchmarks where you just want a single bench() call, but it works until the reporter deduplication gets sorted out.

[tzh476]

The double table came from runBenchmarkSuite emitting suite-finished for the file root, after which the general runSuite wrapper emitted the same event again.

That runner is gone. 19f6e89470 (feat(benchmark)!: rewrite the public API (#10113)) replaced top-level bench() with a test-context fixture. bench is no longer a top-level export of vitest, so this report path cannot fire on current main.

5ab201eb implemented the suite.file === suite skip on the old runner but never landed on main; the rewrite superseded it.

I think this can be closed.