README.md•2.56 kB
# @vitest/snapshot
Lightweight implementation of Jest's snapshots.
## Usage
```js
import { SnapshotClient } from '@vitest/snapshot'
import { NodeSnapshotEnvironment } from '@vitest/snapshot/environment'
import { SnapshotManager } from '@vitest/snapshot/manager'
const client = new SnapshotClient({
// you need to provide your own equality check implementation if you use it
// this function is called when `.toMatchSnapshot({ property: 1 })` is called
isEqual: (received, expected) => equals(received, expected, [iterableEquality, subsetEquality]),
})
// class that implements snapshot saving and reading
// by default uses fs module, but you can provide your own implementation depending on the environment
const environment = new NodeSnapshotEnvironment()
// you need to implement this yourselves,
// this depends on your runner
function getCurrentFilepath() {
return '/file.spec.js'
}
function getCurrentTestName() {
return 'test1'
}
// example for inline snapshots, nothing is required to support regular snapshots,
// just call `assert` with `isInline: false`
function wrapper(received) {
function __INLINE_SNAPSHOT__(inlineSnapshot, message) {
client.assert({
received,
message,
isInline: true,
inlineSnapshot,
filepath: getCurrentFilepath(),
name: getCurrentTestName(),
})
}
return {
// 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)
// you can override this behaviour in SnapshotState's `_inferInlineSnapshotStack` method by providing your own SnapshotState to SnapshotClient constructor
toMatchInlineSnapshot: (...args) => __INLINE_SNAPSHOT__(...args),
}
}
const options = {
updateSnapshot: 'new',
snapshotEnvironment: environment,
}
await client.startCurrentRun(getCurrentFilepath(), getCurrentTestName(), options)
// this will save snapshot to a file which is returned by "snapshotEnvironment.resolvePath"
client.assert({
received: 'some text',
isInline: false,
})
// uses "pretty-format", so it requires quotes
// also naming is hard-coded when parsing test files
wrapper('text 1').toMatchInlineSnapshot()
wrapper('text 2').toMatchInlineSnapshot('"text 2"')
const result = await client.finishCurrentRun() // this saves files and returns SnapshotResult
// you can use manager to manage several clients
const manager = new SnapshotManager(options)
manager.add(result)
// do something
// and then read the summary
console.log(manager.summary)
```