Jest 30 config loading ambiguity with concurrent .cjs and .mjs files
When a project upgrades from Jest 29 to Jest 30 and enables ES modules by setting "type": "module" in package.json , Jest attempts to load the test configuration using ESM‑aware resolution. If both jest.config.cjs and jest.config.mjs are present in the root directory, the loader that Jest 30 selects is not explicitly documented and appears to depend on Node’
jest