Typescript

If you’re authoring your package in Typescript, read this.

Path mappings

For TS modules, a path mapping to resolve the import correctly from the src folder has to be added. This can be done in the top level tsconfig.json:

{
  // ...
  compilerOptions: {
    // ...
    paths: {
      // ...
      '@exodus/networking-spec': ['./modules/networking-spec/src'],
      '@exodus/networking-spec/*': ['./modules/networking-spec/src/*'],
    },
  },
}

The jest config for these modules, then also has to define a custom moduleNameMapper that can be created from the paths definitions in our tsconfig to avoid duplication:

module.exports = {
  moduleNameMapper: pathsToModuleNameMapper(compilerOptions.paths, { prefix: '<rootDir>/../../' }),
};

A full example can be found here 

Please note that referencing files outside/above the module’s directory, will cause tsc to nest its build output in module-name/src and copy the locally referenced dependency to outDir. Make sure an adequate prepack script is provided to cleanup and prepare the build output before packing.