Configuration

A .vitest-dedup.json file is found by walking upward from the analyzed directory, or named with --config. Command-line flags override it.

{
  "include": ["src/**/*.test.ts"],
  "exclude": ["**/fixtures/**"],
  "threshold": 0,
  "rules": { "subsumed-test": "warning" }
}

Keys

Every key is optional, and an unknown key is an error.

Key	Meaning
include, exclude	Globs relative to the analyzed directory.
threshold	A percentage from 0 to 100.
rules	Maps a rule id to off, warning or error.

Files matched by .gitignore or by a .vitest-dedupignore file in the same syntax are skipped as well.

Glob semantics

Single * and ? wildcards stay within a path component; use ** to match across directories. This also applies to resolved Vitest project globs and project paths, and to the base revision --baseline-from-ref reads.

How Vitest configuration is read

VitestDedup reads test.include, test.exclude, test.globals, project lists, and the typecheck channel from vitest.config.* and vite.config.* without executing them.

Test file naming

*.test.* and *.spec.* are recognized by default. A Vitest config that declares its own include replaces that list, so a project naming **/*.unit.ts gets exactly those files. An include written in .vitest-dedup.json is an instruction and is never widened by a project’s broader list.

Differences from the set Vitest runs:

• The analyzer applies its own default exclude list when none is written: node_modules, dist, build, coverage, .idea, .git, .cache, .output and .temp. Vitest’s default excludes only node_modules and .git, so test files under build/ or coverage/ are not analyzed.
• Hidden (dot-prefixed) directories are skipped.
• includeSource is additive. A file matching it is also scanned for in-source tests, whether or not include matches it.

Monorepos

A config declaring test.projects, or a vitest.workspace.* file, is resolved entry by entry, honouring extends: false.

Globals

globals: true is detected from the resolved config. When the project list is built in a way no static reader can follow, such as a bare variable or mergeConfig with a dynamic import, the setting is reported as undetermined and the flag is needed:

vitest-dedup . --globals

The flag is opt-in because ambient describe and it cannot be told apart from Cypress, Mocha, or Jasmine without project configuration, and guessing would invent findings in those files.

Runs that analyze no tests

When no executable tests are analyzed and no quality-gate failure applies, the command exits with operational-error code 2 instead of treating an empty report as clean. A real suite-level quality failure or too many new findings under --fail-on-new remains exit 1.

• If test-shaped files were read but yielded no tests, the diagnostic reports that observation and suggests checking both test.globals (or --globals) and build-time transforms such as auto-imports. It does not claim either cause was proved.
• Known cases, such as statically empty .each/.for tables, receive a more specific diagnostic.

Limits

Source size, nesting and work limits, and the memory budget, are on Incomplete runs and limits.

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