label experimental 4.1.3+

• Type: string
• CLI: --label=<label>

Label for the current test run. When set, the label is displayed alongside test results in the reporter output, and stored in the blob when using --reporter=blob.

During --merge-reports, results from the same test files with different labels are kept as separate entries. The label is also included in the default blob output filename (e.g. blob-linux.json) to avoid collisions between runs on different machines.

Example

Run with a label on each platform:

vitest run --reporter=blob --label=linux
vitest run --reporter=blob --label=macos

Or set it via config, typically driven by an environment variable in CI:

vitest.config.ts

import { defineConfig } from 'vitest/config'

export default defineConfig({
  test: {
    label: `${process.platform}-${process.versions.node}`,
    reporters: ['blob'],
  },
})

When merging, each label is displayed as a separate entry in the reporter output:

vitest --merge-reports

 ✓  linux  src/basic.test.ts (2 tests)
 ✓  macos  src/basic.test.ts (2 tests)

See Blob Reporter and the CI setup guide for a full example.