Sample Typescript server with Jest for running tests, configured to use aliases for path resolution.

Updating the tsconfig.json to set the baseUrl and paths specifies to the Typescript transpiler how to resolve modules.

{
  "compilerOptions": {
    "baseUrl": "src",
    "paths": {
      "@/*": ["*"], // resolve all modules prefixed with `@/` from `src` directory
      "database": ["lib/database/index.ts"] // resolves references to database module 
    },
    "module": "commonjs",
    "moduleResolution": "node",
    "outDir": "./dist",
    "target": "es6"
  },
  "exclude": [
    "node_modules"
  ],
  "include": [
    "./src/**/*"
  ]
}

Use a npm module called (module-alias)[https://www.npmjs.com/package/module-alias]. Add the following to the beginning of the src/index.ts to register the module. require('module-alias/register')

We append a _moduleAliases to our package.json.

  ...
  "_moduleAliases": {
    "@": "dist",
    "database": "dist/lib/database"
  }

We use the moduleNameMapper property to specify module resolution using regular expressions and how to resolve matching paths in jest.config.js.

module.exports = {
  // other config  goes here
  // A map from regular expressions to module names that allow to stub out resources with a single module
  moduleNameMapper: {
    "@/(.*)": "<rootDir>/src/$1",
    "database": "<rootDir>/src/lib/database"
  }
};