@vitest/snapshot

Lightweight implementation of Jest's snapshots.

Usage

1import { SnapshotClient } from '@vitest/snapshot'
2import { NodeSnapshotEnvironment } from '@vitest/snapshot/environment'
3import { SnapshotManager } from '@vitest/snapshot/manager'
4
5const client = new SnapshotClient({
6  // you need to provide your own equality check implementation if you use it
7  // this function is called when `.toMatchSnapshot({ property: 1 })` is called
8  isEqual: (received, expected) =>
9    equals(received, expected, [iterableEquality, subsetEquality]),
10})
11
12// class that implements snapshot saving and reading
13// by default uses fs module, but you can provide your own implementation depending on the environment
14const environment = new NodeSnapshotEnvironment()
15
16// you need to implement this yourselves,
17// this depends on your runner
18function getCurrentFilepath() {
19  return '/file.spec.js'
20}
21function getCurrentTestName() {
22  return 'test1'
23}
24
25// example for inline snapshots, nothing is required to support regular snapshots,
26// just call `assert` with `isInline: false`
27function wrapper(received) {
28  function __INLINE_SNAPSHOT__(inlineSnapshot, message) {
29    client.assert({
30      received,
31      message,
32      isInline: true,
33      inlineSnapshot,
34      filepath: getCurrentFilepath(),
35      name: getCurrentTestName(),
36    })
37  }
38  return {
39    // the name is hard-coded, it should be inside another function, so Vitest can find the actual test file where it was called (parses call stack trace + 2)
40    // you can override this behaviour in SnapshotState's `_inferInlineSnapshotStack` method by providing your own SnapshotState to SnapshotClient constructor
41    toMatchInlineSnapshot: (...args) => __INLINE_SNAPSHOT__(...args),
42  }
43}
44
45const options = {
46  updateSnapshot: 'new',
47  snapshotEnvironment: environment,
48}
49
50await client.startCurrentRun(
51  getCurrentFilepath(),
52  getCurrentTestName(),
53  options
54)
55
56// this will save snapshot to a file which is returned by "snapshotEnvironment.resolvePath"
57client.assert({
58  received: 'some text',
59  isInline: false,
60})
61
62// uses "pretty-format", so it requires quotes
63// also naming is hard-coded when parsing test files
64wrapper('text 1').toMatchInlineSnapshot()
65wrapper('text 2').toMatchInlineSnapshot('"text 2"')
66
67const result = await client.finishCurrentRun() // this saves files and returns SnapshotResult
68
69// you can use manager to manage several clients
70const manager = new SnapshotManager(options)
71manager.add(result)
72
73// do something
74// and then read the summary
75
76console.log(manager.summary)