expect-puppeteer

What is expect-puppeteer?

The expect-puppeteer package is a set of utility functions that integrate Jest's expect assertions with Puppeteer's browser automation capabilities. It allows for more readable and expressive tests when working with Puppeteer.

What are expect-puppeteer's main functionalities?

toMatch

This feature allows you to assert that a specific text appears on the page. It simplifies the process of checking for text content within the page.

await expect(page).toMatch('text to match');

toClick

This feature allows you to simulate a click event on a specified element. It is useful for testing interactions with buttons, links, and other clickable elements.

await expect(page).toClick('button#submit');

toFill

This feature allows you to fill out form fields with specified values. It is useful for testing form submissions and input handling.

await expect(page).toFill('input[name="username"]', 'myUsername');

toSelect

This feature allows you to select an option from a dropdown menu. It is useful for testing interactions with select elements.

await expect(page).toSelect('select#dropdown', 'optionValue');

toUploadFile

This feature allows you to simulate file uploads by specifying the file path. It is useful for testing file input elements.

await expect(page).toUploadFile('input[type="file"]', 'path/to/file.txt');

Other packages similar to expect-puppeteer

jest-puppeteer

jest-puppeteer provides a set of utilities to run Puppeteer with Jest. It offers a more comprehensive setup for integrating Puppeteer with Jest, including custom environment setup and teardown, but it does not include the same level of syntactic sugar for assertions as expect-puppeteer.

puppeteer-testing-library

puppeteer-testing-library is a set of utilities for using the Testing Library queries with Puppeteer. It focuses on providing a more user-centric approach to querying and interacting with elements, similar to the philosophy of the Testing Library family of packages.

puppeteer-extra

puppeteer-extra is a modular plugin framework for Puppeteer. It allows you to extend Puppeteer's functionality with plugins, such as stealth mode and adblocker. While it does not provide assertion utilities, it enhances Puppeteer's capabilities in other ways.

README

expect-puppeteer

Assertion library for Puppeteer.

npm install expect-puppeteer

Usage

Modify your Jest configuration:

{
  "setupFilesAfterEnv": ["expect-puppeteer"]
}

Why do I need it

Writing integration test is very hard, especially when you are testing a Single Page Applications. Data are loaded asynchronously and it is difficult to know exactly when an element will be displayed in the page.

Puppeteer API is great, but it is low level and not designed for integration testing.

This API is designed for integration testing:

• It will wait for element before running an action
• It adds additional feature like matching an element using text

Example

// Does not work if button is not in page
await page.click("button");

// Will try for 500ms to click on "button"
await page.toClick("button");

// Will click the first button with a "My button" text inside
await page.toClick("button", { text: "My button" });

The first element to match will be selected

Example

<div class="outer">
  <div class="inner">some text</div>
</div>

// Will match outer div
await expect(page).toMatchElement("div", { text: "some text" });

// Will match inner div
await expect(page).toMatchElement("div.inner", { text: "some text" });

API

Table of Contents

• toClick
• toDisplayDialog
• toFill
• toFillForm
• toMatchTextContent
• toMatchElement
• toSelect
• toUploadFile

expect(instance).toClick(selector[, options])

Expect an element to be in the page or element, then click on it.

• instance <Page|Frame|ElementHandle> Context
• selector <string|MatchSelector> A selector or a MatchSelector to click on.
• options <Object> Optional parameters
  • button <"left"|"right"|"middle"> Defaults to left.
  • count <number> defaults to 1. See UIEvent.detail.
  • delay <number> Time to wait between mousedown and mouseup in milliseconds. Defaults to 0.
  • text <string|RegExp> A text or a RegExp to match in element textContent.

await expect(page).toClick("button", { text: "Home" });
await expect(page).toClick({ type: "xpath", value: "\\a" }, { text: "Click" });

expect(page).toDisplayDialog(block)

Expect block function to trigger a dialog and returns it.

• page <Page> Context
• block <function> A function that should trigger a dialog

const dialog = await expect(page).toDisplayDialog(async () => {
  await expect(page).toClick("button", { text: "Show dialog" });
});

expect(instance).toFill(selector, value[, options])

Expect a control to be in the page or element, then fill it with text.

• instance <Page|Frame|ElementHandle> Context
• selector <string|MatchSelector> A selector or a MatchSelector to match field
• value <string> Value to fill
• options <Object> Optional parameters
  • delay <number> delay to pass to the puppeteer element.type API

await expect(page).toFill('input[name="firstName"]', "James");

expect(instance).toFillForm(selector, values[, options])

Expect a form to be in the page or element, then fill its controls.

• instance <Page|Frame|ElementHandle> Context
• selector <string|MatchSelector> A selector or a MatchSelector to match form
• values <Object> Values to fill
• options <Object> Optional parameters
  • delay <number> delay to pass to the puppeteer element.type API

await expect(page).toFillForm('form[name="myForm"]', {
  firstName: "James",
  lastName: "Bond",
});

expect(instance).toMatchTextContent(matcher[, options])

Expect a text or a string RegExp to be present in the page or element.

• instance <Page|Frame|ElementHandle> Context
• matcher <string|RegExp> A text or a RegExp to match in page
• options <Object> Optional parameters
  • polling <string|number> An interval at which the pageFunction is executed, defaults to raf. If polling is a number, then it is treated as an interval in milliseconds at which the function would be executed. If polling is a string, then it can be one of the following values:
    • raf - to constantly execute pageFunction in requestAnimationFrame callback. This is the tightest polling mode which is suitable to observe styling changes.
    • mutation - to execute pageFunction on every DOM mutation.
  • timeout <number> maximum time to wait for in milliseconds. Defaults to 30000 (30 seconds). Pass 0 to disable timeout. The default value can be changed by using the page.setDefaultTimeout(timeout) method.
  • traverseShadowRoots<boolean> Whether shadow roots should be traversed to find a match.

// Matching using text
await expect(page).toMatchTextContent("Lorem ipsum");
// Matching using RegExp
await expect(page).toMatchTextContent(/lo.*/);

expect(instance).toMatchElement(selector[, options])

Expect an element be present in the page or element.

• instance <Page|Frame|ElementHandle> Context
• selector <string|MatchSelector> A selector or a MatchSelector to match element
• options <Object> Optional parameters
  • polling <string|number> An interval at which the pageFunction is executed, defaults to raf. If polling is a number, then it is treated as an interval in milliseconds at which the function would be executed. If polling is a string, then it can be one of the following values:
    • raf - to constantly execute pageFunction in requestAnimationFrame callback. This is the tightest polling mode which is suitable to observe styling changes.
    • mutation - to execute pageFunction on every DOM mutation.
  • timeout <number> maximum time to wait for in milliseconds. Defaults to 30000 (30 seconds). Pass 0 to disable timeout. The default value can be changed by using the page.setDefaultTimeout(timeout) method.
  • text <string|RegExp> A text or a RegExp to match in element textContent.
  • visible <boolean> wait for element to be present in DOM and to be visible, i.e. to not have display: none or visibility: hidden CSS properties. Defaults to false.

// Select a row containing a text
const row = await expect(page).toMatchElement("tr", { text: "My row" });
// Click on the third column link
await expect(row).toClick("td:nth-child(3) a");

expect(instance).toSelect(selector, valueOrText)

Expect a select control to be present in the page or element, then select the specified option.

• instance <Page|Frame|ElementHandle> Context
• selector <string|MatchSelector> A selector or a MatchSelector to match select element
• valueOrText <string> Value or text matching option

await expect(page).toSelect('select[name="choices"]', "Choice 1");

expect(instance).toUploadFile(selector, filePath)

Expect a input file control to be present in the page or element, then fill it with a local file.

• instance <Page|Frame|ElementHandle> Context
• selector <string|MatchSelector> A selector or a MatchSelector to match input element
• filePath <string|Array<string>> A file path or array of file paths

import { join } from "node:path";

await expect(page).toUploadFile(
  'input[type="file"]',
  join(__dirname, "file.txt"),
);

Match Selector

An object used as parameter in order to select an element.

• type <"xpath"|"css"> The type of the selector
• value <string> The value of the selector

{type:'css', value:'form[name="myForm"]'}
{type:'xpath', value:'.\\a'}

Configure default options

To configure default options like timeout, expect-puppeteer exposes two methods: getDefaultOptions and setDefaultOptions. You can find available options in Puppeteer page.waitForFunction documentation. Default options are set to: { timeout: 500 }.

import { setDefaultOptions } from "expect-puppeteer";

setDefaultOptions({ timeout: 1000 });

Changelog

11.0.0 (2024-12-21)

Features

• @jest/globals support (#606) (911b243)
• add support for Node.js v22-23 (d67228e)

BREAKING CHANGES

• Node.js v16 is not supported