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.

Tests

$ npm test

Authors

• Nicholas Kyriakides, @nicholaswmin