Mocking LucidORM

[nickabb]

I'd like to be able to mock the AdonisJS models in order to not have to hit a live database for unit tests. I understand your comments on mocking - but I think we'll have to agree to disagree here - I'd still like to be able to do this in order to speed up tests.

Passing in each model as a parameter and then overriding them for tests works, but I'm trying to avoid that (this is the point of using an IoC container after all).

How can I do this?

[RomainLanz]

Hey @nickabb! 👋🏻

That would be way easier to create an abstraction and change that abstraction during your test.

You can follow the repository pattern, for example.

class LucidUserRepository {
  getAll() { return User.all() }
}

const users = []
class InMemoryUserRepository {
  getAll() { return users }
}

abstract class UserRepository {
  abstract getAll()
}

Register inside a provider the abstraction you want to use:

export default class AppProvider {
  constructor(protected app: ApplicationContract) {}
  
  public async boot() {
    const LucidUserRepository = await import('infrastructure/repositories/user.lucid.repository')
    this.app.container.bind('UserRepository', () =>
      this.app.container.make(LucidUserRepository.default)
    )
  }
}

Then inject the class using the IoC Container:

@inject(['UserRepository'])
class UserController {
  constructor (private repository: UserRepository) {}
  
  index() {
    return this.repository.getAll()  
  }
}

Swap the implementation during testing:

test.group('User', (group) => {
  group.setup(() => {
    Application.container.useProxies(true)

    return () => {
      Application.container.useProxies(false)
    }
  })
  
  group.each.setup(async () => {
    return () => Application.container.restore()
  })
  
  test('...', async ({ assert }) => {
    Application.container.fake('UserRepository', () => {
      return new InMemoryUserRepository()
    }))
    
    // ...
  })
}

This flow will be greatly simplified in V6.

[nickabb]

Thanks for this!

First thoughts is that this is sort of what I was trying to avoid (a ton of boilerplate just for tests) - I'd have to write an abstraction over every model to call through to a library model - and there would be a bunch of refactoring to inject the repositories into the constructors of each controller (not horrible, but still a tangible amount of work that compounds with project size)

You mentioned v6 - what will this look like in v6? Possible there are any docs so I could understand further if it would be worth an early upgrade?

[RomainLanz]

In AdonisJS 6, you will not have to use a string-based mapping.
You can watch our live stream on the subject to learn more about the new IoC.

Concerning your request, there is no other way to do it properly. Abstraction is needed to cleanly "mock" your dependency.