npm / mocha

mocha

What changed in mocha 11 to 12, from its official release notes, upgrade guides and advisories. Sources checked 2026-10-17.

1 breaking2 new APIs and options15 fixes and other

See which of these apply to your code, ranked, in your agent:

npx @unstale/cli init

mocha 1214 changes

Shows the require() error for unsupported directory imports.
12.0.3release notes
Watch mode keeps running when the last test file is removed.
12.0.3release notes
The detection window for --exit is widened.
12.0.2release notes
Mocha works around ERR_PACKAGE_PATH_NOT_EXPORTED using find-up-simple.
12.0.2release notes
The spec file path is propagated when a parallel worker dies.
12.0.2release notes
A reporter option specified on the CLI takes precedence over the value in the config file.
12.0.2release notes
Existing directories are watched so the first run starts armed.
12.0.2release notes
Unknown configuration values are no longer treated as test specs.
12.0.1release notes
Only positional arguments that are entirely numeric are rejected.
12.0.1release notes
Embedded stacks render once after splitting err.stack at the trailing frame block.
12.0.1release notes
Fixes parsing of negative numbers and quoted strings.
12.0.0release notes
Preserves FIFO descriptors when respawning.
12.0.0release notes

Mocha now surfaces ts-node compile errors so developers can see failures when compiling tests.
11.7.7release notes
Fixed describe().timeout() so it works.
11.7.6release notes
Mocha swallows more require errors from TypeScript files.
11.7.5release notes