prefer-storybook-test-flag

Detects CI jobs that build Storybook for tests (Storybook Test Runner or Chromatic) without the --test flag.

Why it matters

Storybook 7.6 introduced a test build mode. Passing --test to storybook build (or setting SB_TESTBUILD=true) skips work that tests do not need: docs compilation, docgen analysis, and sourcemaps. Storybook measured test builds 2-4x faster with it, with smaller output.

The win is largest for docs-heavy Storybooks. It only applies to builds consumed by tests (Storybook Test Runner, Chromatic) — a build that is published with docs must not use --test.

What it flags

A finding is emitted when all of the following hold:

1. The repository Storybook dependency is 7.6 or newer (the flag is available).
2. A job runs a direct Storybook build command (build-storybook or storybook build, not via an npm/yarn/pnpm/bun script wrapper).
3. The same job also runs a test consumer (test-storybook, storybook test, @storybook/test-runner, chromatic, chromaui/action, or chromatic-com/storybook).
4. The build command does not pass --test, and the workflow does not set SB_TESTBUILD=true.

Suggested action

Add --test to the Storybook build command (or set SB_TESTBUILD=true) when the build is only used for tests, not for publishing.

- npx build-storybook
+ npx build-storybook --test

Verification

Compare build-storybook wall-clock time and output size with and without --test. Expect a larger gain when docs and autodocs are enabled.

Compatibility notes

• --test requires Storybook 7.6+.
• build.test values in main.ts only apply when --test is passed.
• Do not use --test for a Storybook build that is published with documentation.