Extending a functionality of a module from node module jest is not seeing this

[Bubuioc]

declare module 'typeorm' {
  // eslint-disable-next-line @typescript-eslint/no-unused-vars
  interface SelectQueryBuilder<Entity> {
    andWhereNotExpired(alias?: string): this;
  }

  // eslint-disable-next-line @typescript-eslint/no-unused-vars
  interface UpdateQueryBuilder<Entity> {
    andWhereNotExpired(): this;
  }
}

For this to work i import in my main.ts this

import 'src/modules/messages/typeorm/query.builder.extension';

Run project and it is working fine but when i try to run e2e test it fails, saying that my andWhereNotExpired is not a function
package.json

 "jest": {
    "moduleFileExtensions": [
      "js",
      "json",
      "ts"
    ],
    "rootDir": "./",
    "testRegex": ".*\\.spec\\.ts$",
    "transform": {
      "^.+\\.(t|j)s$": "ts-jest"
    },
    "collectCoverageFrom": [
      "**/*.(t|j)s"
    ],
    "coverageDirectory": "../coverage",
    "testEnvironment": "node",
    "setupFiles": [
      "dotenv/config"
    ]
  },

tsconfig.json

{
  "compilerOptions": {
    "module": "commonjs",
    "declaration": true,
    "removeComments": true,
    "emitDecoratorMetadata": true,
    "experimentalDecorators": true,
    "allowSyntheticDefaultImports": true,
    "target": "ES2023",
    "sourceMap": true,
    "outDir": "./dist",
    "baseUrl": "./",
    "incremental": true,
    "skipLibCheck": true,
    "strictNullChecks": false,
    "noImplicitAny": false,
    "strictBindCallApply": false,
    "noFallthroughCasesInSwitch": false
  }
}

[sunnypatell]

@Bubuioc the declare module 'typeorm' statement only provides TypeScript types. the actual runtime code that patches SelectQueryBuilder.prototype.andWhereNotExpired = ... lives in a file that's imported by main.ts, which Jest doesn't execute during tests.

add the augmentation import to Jest's setup in your config:

{
  "jest": {
    "setupFiles": [
      "<rootDir>/src/modules/messages/typeorm/query.builder.extension"
    ]
  }
}

or in jest.config.ts:

export default {
  setupFiles: [
    './src/modules/messages/typeorm/query.builder.extension',
  ],
};

this ensures the prototype extensions are loaded before any test runs. setupFiles runs before the test framework is installed, which is the right timing for global prototype patches.

ref: Jest setupFiles docs