"no such table: users" when testing and using Bookshelf / Knex

I'm trying to run a simple test using Mocha and my Bookshelf / Knex model, however I'm getting the error "Unhandled rejection Error: SQLITE_ERROR: no such table: users". Note that I'm trying to use in memory SQLite.

Here's my Knexfile:

module.exports = {

  development: {
    client: 'sqlite3',
    connection: {
      filename: ':memory:'
    }
  },

  test: {
    client: 'mysql',
    connection: {
      host: '172.18.0.2',
      user: 'root',
      password: '',
      database: 'staging_db',
      charset  : 'utf8'
    },
    pool: {
      min: 2,
      max: 10
    },
    migrations: {
      tableName: 'knex_migrations'
    }
  },

  production: {
    client: 'mysql',
    connection: {
      host: process.env.DB_HOST || 'localhost',
      user: process.env.DB_USER || 'usr',
      password: process.env.DB_PWD || '',
      database: process.env.DB_NAME || 'db',
      charset  : 'utf8'
    },
    pool: {
      min: 2,
      max: 10
    },
    migrations: {
      tableName: 'knex_migrations'
    }
  }

};

Database.js:

var config      = require('../knexfile.js');  
var env         = process.env.NODE_ENV || 'development';  
var knex        = require('knex')(config[env]);

knex.migrate.latest([config]);

let bookshelf = require('bookshelf')(knex);

bookshelf.plugin('registry'); // Resolve circular dependencies with relations

// Export bookshelf for use elsewhere
module.exports = bookshelf;

And my User model:

let bookshelf = require('../config/database');

require('./role');

var User = bookshelf.Model.extend({
    tableName: 'users',
    role: function() {
        return this.hasOne(Role);
    }
});

module.exports = bookshelf.model('user', User);

And my test:

var User = require('../../models/user'),
    chai = require('chai'),
    expect = chai.expect;

describe('User model', function () {

    it('should return empty set before adding anything', () => {
        expect(User.collection().count()).to.equal(0); 
    });

});

Am I missing something?

UPDATE

Adding the migration file:

exports.up = function(knex, Promise) {
  return knex.schema.createTable('roles', function (table) {
        //this creates an id column as auto incremented primary key
        table.increments();
        table.string('description', 45).notNullable();
    })
    .createTable('users', function (table) {
        table.increments();
        table.string('name', 60);
        table.string('password', 45);
        table.integer('role_id').unsigned();
        table.foreign('role_id').references('roles.id');
    });
};

exports.down = function(knex, Promise) {
  return knex.schema.dropTable('users').dropTable('roles');
};