Mock-repo NPM | npm.io

mock-repo

A Node.js generic mock repo for simulating repositories in the Repository Pattern. Helps to avoid touching the database when testing business logic

Installation

$ npm install --save-dev mock-repo

Overview

This module exports an ES6 Class with simple methods that are most commonly present in Repositories. You can extend if you need more methods.

Usage

A Class can be persisted if it satisfies the following criteria:

1st argument of it's constructor accepts an Object that contains at least all the persistable properties.
It has a props property that contains all the props that should be persisted.

class User {
  constructor({ id_user = Guid.raw(), name }) {
    this.props = {
      id_user,
      name
    }

    // Anything outside `props` will *not* be persisted
    // - e.g `age` property will not be persisted
    this.age = 15
  }

  getName() {
    return this.name
  }
}

upsert(db, instance)

If the provided object pre-exists by primaryKey, then the repo will update the existing object, otherwise it will insert it.

get(db, filter)

Returns an item by some specified criteria.

You can include multiple criteria, but be aware that all criteria must match (it simulates an SQL andWhere()).

getAll(db, filter)

Same as get() but returns multiple instances. If no filter is provided, it returns all instances.

Example

In the following example we are going to:

Insert a user with name 'John Doe' and id_user 1.
Then update his name to 'John Doooe'.
Then get him back by the id_user we used when we first inserted him.

The following example assumes your Class looks like this:

class User {
  constructor({ id_user = Guid.raw(), name }) {
    this.props = {
      id_user,
      name
    }
  }
}

Then:

const MockRepo = require('mock-repo')
const userRepo = new MockRepo({
  primaryKey: 'id_user',
  constructAs: data => new User(data)
})

/*
 * 1st argument on *all* methods is supposed to be the `db` object in
 * production, when you actually use a real database.
 *
 * You can pass `null` when using this module
 */
userRepo.upsert(null, new User({ id_user: 1, name: 'John Doe' }))
  .then(() => {
    return userRepo.upsert(null, new User({ id_user: 1, name: 'John Doooe' }))
  })
  .then(() => {
    return userRepo.get(null, { id_user: 1 })
  })
  .then(result => {
    console.log(result) // logs `User { id_user: 1, name: 'John Doooe' }`
    console.log(userRepo.items.length) // logs '1'
    return
  })

Note: Stored items are held in the items prop of the Mock Repo, i.e userRepo.items, will return all the stored users.