snapshotFormat

• Type: Omit<PrettyFormatOptions, 'plugins' | 'compareKeys'> & { compareKeys?: null | undefined }

Format options for snapshot testing. These options configure the snapshot-specific formatting layer built on top of @vitest/pretty-format.

For the full option surface of PrettyFormatOptions, see @vitest/pretty-format. This page focuses on the Vitest snapshot-specific defaults and constraints.

Vitest snapshots already apply these defaults before your snapshotFormat overrides:

• printBasicPrototype: false
• escapeString: false
• escapeRegex: true
• printFunctionName: false

Vitest also supports formatter options such as printShadowRoot and maxOutputLength in snapshotFormat.

printShadowRoot controls whether shadow-root contents are included in DOM snapshots.

maxOutputLength is an approximate per-depth output budget, not a hard cap on the final rendered string.

By default, snapshot keys are sorted using the formatter's default behavior. Set compareKeys to null to disable key sorting. Custom compare functions are not supported in snapshotFormat.

TIP

Beware that plugins on this object will be ignored.

If you need to extend snapshot serialization via pretty-format plugins, use expect.addSnapshotSerializer or snapshotSerializers instead.