Knex.js Mock

knex-mock.js

import _ from 'lodash'

// In-memory Knex mock 🤯
function DB () {
  const db = function (table) {
    if (!table) return db
    db._table = table
    if (!db._db[table]) {
      db._db[table] = {
        _latestId: 0,
        _items: {},
      }
    }
    db._result = db._db[table]
    return db
  }

  db._db = {}
  db._table = null
  db._result = []
  this._select = i => i

  db.transaction = cb => cb(db)

  db.insert = item => {
    const table = db._db[db._table]
    table._latestId++
    item.id = table._latestId
    table._items[item.id] = item
    db._result = [item]
    return db
  }

  db.select = columns => {
    const all = _.includes(columns, '*')
    this._select = all ? (i => i) : (i => _.pick(i, columns))
    return db
  }

  db.where = (column, value) => {
    const table = db._db[db._table]
    db._result = _.filter(table._items, { [column]: value }).map(this._select)
    this._select = i => i
    return db
  }

  db.then = cb => {
    return cb(_.cloneDeep(db._result))
  }

  return db
}

const mock = new DB()