Unable to mock typeorm datasource - jestjs

Question

Below is the file where I am trying to mock datasource. but Getting error as
TypeError: Cannot set property DataSource of [object Object] which has only a getter
import { AppService } from '../services';
import typeorm = require('typeorm');
describe("Tests for AppService", () => {
beforeAll(() => {
typeorm.DataSource = jest.fn().mockReturnValue({
manager: {
find: jest.fn(),
query: jest.fn(),
}
})
});
it("should call getServices", () => {
const AS = new AppService();
AS.getServices(1);
expect(typeorm.DataSource).toHaveBeenCalled();
});
})
datasource file
import { DataSource } from 'typeorm';
import { services } from '../entity/services';
import { versions } from '../entity/versions';
export const connectDB = new DataSource({
type: 'postgres',
host: 'localhost',
port: 5431,
username: 'postgres',
password: 'password',
database: 'test',
synchronize: true,
logging: true,
entities: [services, versions],
subscribers: [],
migrations: [],
});
connectDB
.initialize()
.then(() => {
console.log(`Data Source has been initialized`);
})
.catch((err) => {
console.error(`Data Source initialization error`, err);
});
export default connectDB;
And I am using it like,
import { Injectable } from '#nestjs/common';
import { Like } from 'typeorm';
import connectDB from '../config/db_connection';
import { services } from '../entity/services';
import { versions } from '../entity/versions';
// handle errors //
// write function description
#Injectable()
export class AppService {
public getServices(id: number): Promise<versions[]> {
return connectDB.manager.find(versions, {
relations: {
service: true,
Is there any better way to mock typeorm datasource in jest.
Thanks

Answer 1

This is the way I implement it in a repo of mine:
import { DataSource } from 'typeorm'
const makeDataSourceMock = (): DataSource => ({
name: 'any_data_source',
options: { database: 'any_database' },
destroy: jest.fn(),
manager: { save: jest.fn() },
getRepository: jest.fn(() => ({
clear: jest.fn()
})),
entityMetadatas: [
{ name: 'any_entity_name' }
]
}) as any
Here is the complete test file if you want to take a look: https://github.com/leal32b/webapi-nodejs/blob/main/test/core/3.infra/persistence/postgres/client/postgres-client.unit.test.ts