jest collectCoverageFrom missing files: how to fix

TL;DR

collectCoverageFrom only adds files matching its globs, and coveragePathIgnorePatterns can silently remove them again. Fix the glob first, then check the ignore list. Verify with --coverage and an explicit --collectCoverageFrom on the command line before touching config.

Problem

The coverage report omits source files you expect to see, usually showing only files touched by tests.

Steps

1. Run jest with an explicit flag: npx jest --coverage --collectCoverageFrom='src/*/.[jt]s?(x)'. Expected: the report now lists untouched files.
2. If that works, move the glob into the Jest config collectCoverageFrom. Expected: plain npx jest --coverage shows the same files.
3. Check coveragePathIgnorePatterns for entries swallowing your files. Expected: removing the stray pattern brings the files back.
4. Confirm collectCoverage is true or the --coverage flag is used; without it the from-list does nothing. Expected: coverage output appears at all.
5. For files with zero tests, confirm they are still listed with 0 percent coverage. Expected: untouched files appear instead of vanishing.

When to use

• Jest 29 or 30 coverage report is missing source files.
• You want coverage enforced on untested files too.
• Migrating from an older Jest where defaults differed.

When not to use

• Coverage numbers look wrong rather than files missing; check the provider (babel vs v8).
• Files are excluded on purpose; keep them in coveragePathIgnorePatterns.
• You only care about files touched by tests; the default behavior is fine.

Tool compatibility

• Jest 29.x, 30.x: collectCoverageFrom globs are relative to rootDir.
• coverageProvider 'babel' (default) and 'v8' both honor the from-list.

Variant phrasings

jest coverage missing untested files

Same fix; untested files only appear via collectCoverageFrom.

collectCoverageFrom glob not matching

Quote the glob so the shell does not expand it, and check with --showConfig that Jest received it intact.

Why it happens

By default Jest only instruments files that tests actually require. collectCoverageFrom is the opt-in list that pulls the rest of the source tree into the report, so a wrong glob or an ignore pattern quietly drops files.

Edge cases

• The v8 provider and babel provider can disagree on which lines count; file presence is the same though.
• Negation patterns like '!src/generated/**' must come after the positive glob.
• On Windows, use forward slashes in globs; backslashes get misread.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_AU5TZw08mCx-8DD2GoEFsQ