@shutter/core

Core testing library for shutter.sh. This is the framework-agnostic base code that the framework-specific packages are based on.

Sends an HTML document to the shutter.sh service in order to render a PNG snapshot and save that snapshot locally. Future test runs will re-render the content and compare it against the previously saved snapshot.

The tests will fail if the current snapshot does not match the expected one. If that visual change was intended, you can update your local snapshot.

Find it on GitHub.

Table of Contents

API

// Basic usage
import createShutter from '@shutter/core'
const shutter = createShutter(__dirname)
async function run () {
await shutter.snapshot('New UI', '<div>Renders any HTML.</div>')
await shutter.finish()
}
run()
// Uploading local files
import createShutter, { addFile } from '@shutter/core'
import * as path from 'path'
const files = await Promise.all([
addFile(path.join(__dirname, 'styles.css'), '/styles.css')
])
const head = `
<link href="/styles.css" rel="stylesheet" />
`
const shutter = createShutter(__dirname, { files, head })
async function run () {
await shutter.snapshot('New UI', '<div class="my-content">Renders any HTML.</div>')
await shutter.finish()
}
run()

createShutter(testDirectoryPath: string, options: ShutterOptions): Shutter

Creates a shutter instance. You need to pass your testing directory (can usually just use __dirname), so it knows where to save the snapshots.

interface ShutterOptions {
/** Local files to upload, like stylesheets. Use `addFile()` to populate this array. */
files?: File[],
/** Custom content to go into the <head> tag of the document. */
head?: string,
/** Layout to use for rendering. Pass a custom layout to change the overall page structure. */
layout?: (bodyContent: string, headContent: string) => string,
/** Set a custom path to your local snapshot files here. */
snapshotsPath?: string,
/** Set custom image comparison options here. Used to compare the current snapshot to the expectation. */
diffOptions?: DiffOptions,
/** Set custom rendering options here. */
renderOptions?: RenderOptions
}

Check out the @shutter/api documentation for the File, DiffOptions and RenderOptions details.

shutter.snapshot(testName: string, html: string, options: SnapshotOptions = {}): Promise

Send page contents to the shutter.sh service to be rendered.

The returned promise will resolve once the upload is done, but before the rendering has finished. That is why you need to call shutter.finish() after calling shutter.snapshot() the last time.

interface SnapshotOptions {
layout?: (htmlContent: string) => string,
diffOptions?: DiffOptions,
renderOptions?: RenderOptions
}

The options are mostly the same as the ShutterOptions. They can be used to override the options per test case.

Check out the @shutter/api documentation for the DiffOptions and RenderOptions details.

shutter.finish(): Promise<TestResult[]>

Waits until all rendering tasks have finished, then collects and evaluates the results.

Will throw with a test results summary if snapshots don't match. Prints a success message and an inspection link if everything matched.

addFile(localPath: string, serveAsPath: string): Promise

Reads a local file and prepares it for submission along the HTML content to render. Use it to submit local stylesheets, images, etc.

Pass the resulting File to createShutter() as options.files.

Note: The submitted file will be publicly accessible.

createFileFromBuffer(content: Buffer, fileName: string, options: FileCreationOptions = {}): File

Allows you to submit a file from in-memory contents.

interface FileCreationOptions {
contentType?: string
}

Note: The submitted file will be publicly accessible.