vitest-dev/vitest · error · Error

Tag name " " is invalid. Tag names cannot contain spaces.

Error message

Tag name "${tag.name}" is invalid. Tag names cannot contain spaces.

What it means

Tag names cannot contain whitespace (`/\s/`). Vitest uses tag names in CLI filters and boolean tag expressions where spaces would break tokenisation, so any whitespace is rejected with the offending name in the message.

Solutions

Use a single token: `smoke-test`, `smoke_test`, or `smokeTest`.
Trim and validate before export: `name: rawName.trim()` and assert `!/\s/.test(name)`.
Keep a human-readable `description`/`label` field separate from the machine `name` if your config supports it.

Example fix

// before
export default defineConfig({ test: { tags: [{ name: 'smoke test' }] } })

// after
export default defineConfig({ test: { tags: [{ name: 'smoke-test' }] } })

Defensive patterns

Strategy: validation

Validate before calling

function assertNoSpaces(name: string): void {
  if (/\s/.test(name)) {
    throw new Error(`Tag name "${name}" must not contain whitespace`)
  }
}

const clean = rawTags.map(t => ({ ...t, name: t.name.trim() }))
clean.forEach(t => assertNoSpaces(t.name))

Type guard

function isWhitespaceFreeName(name: string): boolean {
  return typeof name === 'string' && !/\s/.test(name)
}

Prevention

Use kebab-case or snake_case for machine tag names.
Trim and validate tag names at config build time.
Keep human-readable labels in a separate `description` field.

When it happens

Trigger: `{ name: 'smoke test' }`, `{ name: 'flaky\t' }`, `{ name: 'a b' }`, or names with leading/trailing spaces from copy-paste.

Common situations: Pasting human-readable labels as tag names; importing tags from a spreadsheet/CSV that preserved spaces; typos with tabs/newlines.

Related errors

AI-assisted analysis of vitest-dev/vitest@1fa9837ec2 (2026-08-11). Data as JSON: /api/errors/ddece76a943e6160. Report an issue: GitHub.

Appendix: source

Thrown at packages/vitest/src/node/config/resolveConfig.ts:296

  }

  resolved.pool ??= 'forks'

  resolved.project = toArray(resolved.project)
  resolved.provide ??= {}

  // shallow copy tags array to avoid mutating user config
  resolved.tags = [...resolved.tags || []]
  const definedTags = new Set<string>()
  resolved.tags.forEach((tag) => {
    if (!tag.name || typeof tag.name !== 'string') {
      throw new Error(`Each tag defined in "test.tags" must have a "name" property, received: ${JSON.stringify(tag)}`)
    }
    if (definedTags.has(tag.name)) {
      throw new Error(`Tag name "${tag.name}" is already defined in "test.tags". Tag names must be unique.`)
    }
    if (/\s/.test(tag.name)) {
      throw new Error(`Tag name "${tag.name}" is invalid. Tag names cannot contain spaces.`)
    }
    if (/[!()*|&]/.test(tag.name)) {
      throw new Error(`Tag name "${tag.name}" is invalid. Tag names cannot contain "!", "*", "&", "|", "(", or ")".`)
    }
    if (/^\s*(?:and|or|not)\s*$/i.test(tag.name)) {
      throw new Error(`Tag name "${tag.name}" is invalid. Tag names cannot be a logical operator like "and", "or", "not".`)
    }
    if (typeof tag.retry === 'object' && typeof tag.retry.condition === 'function') {
      throw new TypeError(`Tag "${tag.name}": retry.condition function cannot be used inside a config file. Use a RegExp pattern instead, or define the function in your test file.`)
    }
    if (tag.priority != null && (typeof tag.priority !== 'number' || tag.priority < 0)) {
      throw new TypeError(`Tag "${tag.name}": priority must be a non-negative number.`)
    }
    definedTags.add(tag.name)
  })

  resolved.name = typeof options.name === 'string'
    ? options.name

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