JavaScript Guide

As you know, TypeORM also supports JavaScript. However, we need to follow a slightly different approach to create a Repository because we cannot use TypeScript-like decorators in JavaScript. So we need to use EntitySchema for that. Here’s how you can do this:

Create a Repository

import { EntitySchema } from 'typeorm'

const User = new EntitySchema({ name: 'User', tableName: 'users', columns: [] })

Mock EntitySchema methods

To mock User methods, e.g., find, here’s how you can do it:

it('test', async () => {
  const mockUsers = ['user']
  const typeorm = new MockTypeORM()
  typeorm.onMock('User').toReturn(mockUsers, 'find')

  const users = await dataSource.getRepository(User).find()

  expect(users).toEqual(mockUsers)
})

Important Note

In the onMock method, when we are using JavaScript, we always provide the Repository name as a string, and it should match the object name of the EntitySchema, e.g., we just created the User object before:

const User = new EntitySchema({ ... });

So you must provide "User" in the onMock function argument. If the object name is different, e.g.,

const UserEntity = new EntitySchema({ ... });

then you need to provide "UserEntity" in the onMock function argument. Here’s the test case for that:

it('test', async () => {
  const mockUsers = ['user']
  const typeorm = new MockTypeORM()
  typeorm.onMock('UserEntity').toReturn(mockUsers, 'find')

  const users = await dataSource.getRepository(UserEntity).find()

  expect(users).toEqual(mockUsers)
})

Everything else remains the same as we are doing with TypeScript. The only change is that when calling the onMock function, we need to provide the Repository name as a string.