tsconfig.json

{
  "compilerOptions": {
    "target": "es6",
    "module": "commonjs",
    "lib": ["es2015"],
    "declaration": true,
    "declarationMap": true,
    "sourceMap": true,
    "skipLibCheck": true,

    "strict": true,
    "noImplicitReturns": true,
    "noFallthroughCasesInSwitch": true,
    "exactOptionalPropertyTypes": true,
    "noUncheckedIndexedAccess": true,
    "noPropertyAccessFromIndexSignature": true,
    "forceConsistentCasingInFileNames": true,
    "noUnusedLocals": true,
    "noUnusedParameters": true,

    "moduleResolution": "node",
    "esModuleInterop": true
  },
  // See: https://www.typescriptlang.org/docs/handbook/project-references.html#overall-structure
  //
  // Another good practice is to have a “solution” tsconfig.json file that simply has
  // references to all of your leaf-node projects and sets files to an empty array
  // (otherwise the solution file will cause double compilation of files)
  "files": [],
  "references": [{ "path": "./src" }, { "path": "./test" }]
}