snapshot-context

snapshot-context is Context For Snapshot Testing In Zoroaster.

yarn add -DE snapshot-context

Since Zoroaster 3.8.5, the snapshot functionality is enabled by returning the result of the test, there's no need to install this package manually.

Table Of Contents

• Table Of Contents
• class SnapshotContext
• API
  • setDir(path:string)
  • async test(path:string, actual: string|object)
• Copyright & License

class SnapshotContext

The snapshot context should be passed in to a Zoroaster test suite in the context property.

import { fork } from 'spawncommand'
import SnapshotContext from 'snapshot-context'
import Context from '../context'

/**
 * @type {Object.<string, (c: Context, s: SnapshotContext)>} */
const T = {
  context:[
    context,
    snapshotContext,
  ],
  async 'produces correct output'({ TEST_SUITE_PATH }, { test, setDir }) {
    setDir(SNAPSHOT_DIR)
    const { promise } = fork(BIN, [TEST_SUITE_PATH, '--babel'], {
      stdio: 'pipe',
    })
    const { stdout } = await promise
    await test('integration-stdout.txt', s)
  },
}

export default T

API

There is a set of methods made available by the API.

setDir(path:string)

Sets the root directory to save to and read snapshots from. Otherwise, an absolute path to the file can be passed. By default, the test/snapshot directory is used.

import { resolve } from 'path'
import snapshotContext, { SnapshotContext } from 'snapshot-context' // eslint-disable-line
import erte from '../../src' // tested lib

const SNAPSHOT_DIR = resolve(__dirname, '../snapshot')

const stringContext = {
  /**
   * A string with 1 new line
   */
  s: 'I am all in a sea of wonders.\nI doubt;\nI fear;\n',
  /**
   * A string with 2 new lines
   */
  t: 'I am all in a sea of wonders.\n\nI doubt;\n\nI fear;\n\n',
}

/** @type {Object.<string, (ctxString: stringContext ctx: SnapshotContext)>} */
const T = {
  context: [
    function () {
      Object.assign(this, stringContext)
    },
    snapshotContext,
  ],
  async 'replaces new lines'({ s, t }, { setDir, test }) {
    setDir(SNAPSHOT_DIR)
    const res = erte(s, t)
    await test('new-lines.txt', res)
  },
  // absolute path without set-dir
  async 'replaces reverse new lines'({ s, t }, { test }) {
    const res = erte(t, s)
    const path = resolve(SNAPSHOT_DIR, 'new-lines-reverse.txt')
    await test(path, res)
  },
}

export default T

async test(path:string, actual: string|object)

Test whether a snapshot matches the one saved in the path. An equality of strings is asserted, and objects are deep-equal tested. Objects are serialised as JSON for writing, and back when reading.

• If there's no snapshot file existing, the user is prompted to answer the save snapshot question with a y to confirm new snapshot.
• The path to the file will be ensured, so that all directories in the path are made.
• The error stack will start at the point where test is called.

The difference between objects will be shown using deepEqual from the assert-diff

The difference between strings will be highlighted with erte.

Copyright & License

GNU Affero General Public License v3.0

	© Art Deco™ for ContextTesting 2020