Lariat

Page object framework for end-to-end testing in Playwright.

Installation

npm

npm install lariat

Yarn

yarn add lariat

Basic Usage

At the core of Lariat is the Collection class. This class is used to represent a collection of elements in a page or section of a page and can include associated utility methods for interacting with those elements.

To create your own collections, simply create a class which extends the Collection class. You can then define elements using the Collection.el() method which we will explore more in a moment.

import Collection from 'lariat'

class TodoPage extends Collection<Page> {
  input = this.el('#todo-input')
}

With your collection defined, you can instantiate it in your test to access the elements.

test('create a todo', async ({ page }) => {
  const todoPage = new TodoPage(page)
  await todoPage.input.fill('Finish the website')
})

Elements

Elements are defined in collections using the Collection.el() method.

class TodoPage extends Collection<Page> {
  saveButton = this.el('#save-button')
}

Elements are represented using Playwright locators .

const todoPage = new TodoPage(page)
await todoPage.saveButton.click()

has and hasText

The has and hasText locator options can be passed to Collection.el() to match elements that contain a given locator or text.

class TodoPage extends Collection<Page> {
  buttonWithIcon = this.el('button', { has: this.el('svg') })
  saveButton = this.el('button', { hasText: 'Save' })
}

Dynamic selectors

Because collections in Lariat are plain JavaScript classes, you can easily create elements with dynamic selectors. Consider a todo list where we find an item based on it's name. Our collection might look something like this:

class TodoPage extends Collection<Page> {
  item = (name: string) => this.el(`#todo-item[data-name="${name}"]`)
}

const todoPage = new TodoPage(page)
const item = todoPage.item('Finish the website')
await item.click()

Portals

Sometimes, the DOM structure of a page might not match the visual structure exactly. For example, if you use React's createPortal function you can render an element outside the main React tree. To support these use cases, Lariat allows you to pass a portal option to Collection.el() to indicate that the element should not be based off the root element.

class TodoPage extends Collection<Page> {
  modal = this.el('#modal', { portal: true })
}

Utility methods

Because collections are plain JavaScript classes, you can easily add utility methods to your collections.

class TodoPage extends Collection<Page> {
  input = this.el('#todo-input')
  saveButton = this.el('#save-button')

  async create(name: string) {
    await this.input.fill(name)
    await this.input.click()
  }
}

const todoPage = new TodoPage(page)
await todoPage.create('Finish the website')

Nested collections

So far, we've shown examples of simple collections, but Lariat also gives you the ability to nest collections inside each other. With this approach, you can create a page object structure that more closely resembles your page layout.

To nest a collection, use the Collection.nest() method and pass the nested collection class and the root of the nested collection.

class TodoPage extends Collection<Page> {
  field = this.nest(TextField, '#todo-field')
}

const todoPage = new TodoPage(page)
await todoPage.field.input.fill('Finish the website')

If your nested collection is used merely to group a set of related elements together, you can use the parent's root property as the root of the child collection.

class TodoPage extends Collection<Page> {
  field = this.nest(TextField, this.root)
}

If your nested collection exists outside the DOM structure of the parent collection, you can use the parent's frame property as the root of the child collection. This behaves very similarly to the portal option for Collection.el().

class TodoPage extends Collection<Page> {
  modal = this.nest(Modal, this.frame)
}

first, last, and nth

In some cases, you may have a nested collection where multiple instances exist on the page. For example, a todo list may contain multiple todo items each of which are represented as a collection. To make these scenarios easier, Lariat provides first, last, and nth methods which will return a new instance of the nested collection scoped to that specific item.

class TodoPage extends Collection<Page> {
  item = this.nest(TodoItem, '.todo-item')
}

const todoPage = new TodoPage(page)
const firstItem = todoPage.item.first()
const secondItem = todoPage.item.nth(1)
const lastItem = todoPage.item.last()

Frames

Lariat has utilities for working with frames thanks to Playwright's FrameLocator.

The simplest way to access an element in a frame is by using the frame option of Collection.el. Simply pass a string as a selector for the frame and Lariat will take care of the rest.

class FramePage extends Collection<Page> {
  frameHeader = this.el('h1', { frame: '#my-frame' })
}

However, if you need to access multiple elements in a frame, you can use Collection.nest with a FrameLocator.

class MyFrame extends Collection<FrameLocator> {
  header = this.el('h1')
  content = this.el('main')
}

class FramePage extends Collection<Page> {
  myFrame = this.nest(MyFrame, this.page.frameLocator('#my-frame'))
}

You can use a similar method to instantiate collections with a FrameLocator as the root.

class MyFrame extends Collection<FrameLocator> {
  header = this.el('h1')
  content = this.el('main')
}

new MyFrame(page.frameLocator('#my-frame'))

Accessing the page or frame

Lariat makes it easy to access the page or frame that a collection is associated with.

class TodoPage extends Collection {
  input = this.el('#todo-input')
}

const todoPage = new TodoPage(page.locator('#my-page'))
await todoPage.frame.goto('https://google.com')
await todoPage.page.mouse.down()