node_modules/rxjs/src/tsconfig.cjs.spec.json

{
  "extends": "./tsconfig.cjs.json",
  /**
   * this is pseudo config for test case's relative path resolution to `../src`, runs
   * cjs config once more instead of manual copying to utilize incremental build.
   */
  "compilerOptions": {
    "outDir": "../dist/src"
  }
}