feat(snapshot): introduce toMatchFileSnapshot and auto queuing expect promise (#3116)

Author: antfu

docs/api/expect.md

@@ -678,6 +678,22 @@ type Awaitable<T> = T | PromiseLike<T>
   })
   ```
 
+## toMatchFileSnapshot
+
+- **Type:** `<T>(filepath: string, message?: string) => Promise<void>`
+
+  Compare or update the snapshot with the content of a file explicitly specified (instead of the `.snap` file).
+
+  ```ts
+  import { expect, it } from 'vitest'
+
+  it('render basic', async () => {
+    const result = renderHTML(h('div', { class: 'foo' }))
+    await expect(result).toMatchFileSnapshot('./test/basic.output.html')
+  })
+  ```
+
+  Note that since file system operation is async, you need to use `await` with `toMatchFileSnapshot()`.
 
 ## toThrowErrorMatchingSnapshot
 

docs/guide/snapshot.md

@@ -79,6 +79,23 @@ Or you can use the `--update` or `-u` flag in the CLI to make Vitest update snap
 vitest -u
 ```
 
+## File Snapshots
+
+When calling `toMatchSnapshot()`, we store all snapshots in a formatted snap file. That means we need to escaping some characters (namely the double-quote `"` and backtick `\``) in the snapshot string. Meanwhile, you might lose the syntax highlighting for the snapshot content (if they are in some language).
+
+To improve this case, we introduce [`toMatchFileSnapshot()`](/api/expect#tomatchfilesnapshot) to explicitly snapshot in a file. This allows you to assign any file extension to the snapshot file, and making them more readable.
+
+```ts
+import { expect, it } from 'vitest'
+
+it('render basic', async () => {
+  const result = renderHTML(h('div', { class: 'foo' }))
+  await expect(result).toMatchFileSnapshot('./test/basic.output.html')
+})
+```
+
+It will compare with the content of `./test/basic.output.html`. And can be written back with the `--update` flag.
+
 ## Image Snapshots
 
 It's also possible to snapshot images using [`jest-image-snapshot`](https://github.com/americanexpress/jest-image-snapshot).

packages/browser/src/client/snapshot.ts

@@ -22,6 +22,10 @@ export class BrowserSnapshotEnvironment implements SnapshotEnvironment {
     return rpc().resolveSnapshotPath(filepath)
   }
 
+  resolveRawPath(testPath: string, rawPath: string): Promise<string> {
+    return rpc().resolveSnapshotRawPath(testPath, rawPath)
+  }
+
   removeSnapshotFile(filepath: string): Promise<void> {
     return rpc().removeFile(filepath)
   }

packages/expect/src/jest-expect.ts

@@ -8,6 +8,7 @@ import { arrayBufferEquality, generateToBeMessage, iterableEquality, equals as j
 import type { AsymmetricMatcher } from './jest-asymmetric-matchers'
 import { diff, stringify } from './jest-matcher-utils'
 import { JEST_MATCHERS_OBJECT } from './constants'
+import { recordAsyncExpect } from './utils'
 
 // Jest Expect Compact
 export const JestChaiExpect: ChaiPlugin = (chai, utils) => {
@@ -633,6 +634,7 @@ export const JestChaiExpect: ChaiPlugin = (chai, utils) => {
   utils.addProperty(chai.Assertion.prototype, 'resolves', function __VITEST_RESOLVES__(this: any) {
     utils.flag(this, 'promise', 'resolves')
     utils.flag(this, 'error', new Error('resolves'))
+    const test = utils.flag(this, 'vitest-test')
     const obj = utils.flag(this, 'object')
 
     if (typeof obj?.then !== 'function')
@@ -646,7 +648,7 @@ export const JestChaiExpect: ChaiPlugin = (chai, utils) => {
           return result instanceof chai.Assertion ? proxy : result
 
         return async (...args: any[]) => {
-          return obj.then(
+          const promise = obj.then(
             (value: any) => {
               utils.flag(this, 'object', value)
               return result.call(this, ...args)
@@ -655,6 +657,8 @@ export const JestChaiExpect: ChaiPlugin = (chai, utils) => {
               throw new Error(`promise rejected "${String(err)}" instead of resolving`)
             },
           )
+
+          return recordAsyncExpect(test, promise)
         }
       },
     })
@@ -665,6 +669,7 @@ export const JestChaiExpect: ChaiPlugin = (chai, utils) => {
   utils.addProperty(chai.Assertion.prototype, 'rejects', function __VITEST_REJECTS__(this: any) {
     utils.flag(this, 'promise', 'rejects')
     utils.flag(this, 'error', new Error('rejects'))
+    const test = utils.flag(this, 'vitest-test')
     const obj = utils.flag(this, 'object')
     const wrapper = typeof obj === 'function' ? obj() : obj // for jest compat
 
@@ -679,7 +684,7 @@ export const JestChaiExpect: ChaiPlugin = (chai, utils) => {
           return result instanceof chai.Assertion ? proxy : result
 
         return async (...args: any[]) => {
-          return wrapper.then(
+          const promise = wrapper.then(
             (value: any) => {
               throw new Error(`promise resolved "${String(value)}" instead of rejecting`)
             },
@@ -688,6 +693,8 @@ export const JestChaiExpect: ChaiPlugin = (chai, utils) => {
               return result.call(this, ...args)
             },
           )
+
+          return recordAsyncExpect(test, promise)
         }
       },
     })

packages/expect/src/utils.ts

@@ -0,0 +1,18 @@
+export function recordAsyncExpect(test: any, promise: Promise<any>) {
+  // record promise for test, that resolves before test ends
+  if (test) {
+    // if promise is explicitly awaited, remove it from the list
+    promise = promise.finally(() => {
+      const index = test.promises.indexOf(promise)
+      if (index !== -1)
+        test.promises.splice(index, 1)
+    })
+
+    // record promise
+    if (!test.promises)
+      test.promises = []
+    test.promises.push(promise)
+  }
+
+  return promise
+}

packages/runner/src/index.ts

@@ -2,4 +2,5 @@ export { startTests, updateTask } from './run'
 export { test, it, describe, suite, getCurrentSuite } from './suite'
 export { beforeAll, beforeEach, afterAll, afterEach, onTestFailed } from './hooks'
 export { setFn, getFn } from './map'
+export { getCurrentTest } from './test-state'
 export * from './types'

packages/runner/src/run.ts

@@ -145,6 +145,14 @@ export async function runTest(test: Test, runner: VitestRunner) {
         await fn()
       }
 
+      // some async expect will be added to this array, in case user forget to await theme
+      if (test.promises) {
+        const result = await Promise.allSettled(test.promises)
+        const errors = result.map(r => r.status === 'rejected' ? r.reason : undefined).filter(Boolean)
+        if (errors.length)
+          throw errors
+      }
+
       await runner.onAfterTryTest?.(test, retryCount)
 
       test.result.state = 'pass'
@@ -197,10 +205,15 @@ export async function runTest(test: Test, runner: VitestRunner) {
 
 function failTask(result: TaskResult, err: unknown, runner: VitestRunner) {
   result.state = 'fail'
-  const error = processError(err, runner.config)
-  result.error = error
-  result.errors ??= []
-  result.errors.push(error)
+  const errors = Array.isArray(err)
+    ? err
+    : [err]
+  for (const e of errors) {
+    const error = processError(e, runner.config)
+    result.error ??= error
+    result.errors ??= []
+    result.errors.push(error)
+  }
 }
 
 function markTasksAsSkipped(suite: Suite, runner: VitestRunner) {

packages/runner/src/types/tasks.ts

@@ -59,6 +59,10 @@ export interface Test<ExtraContext = {}> extends TaskBase {
   fails?: boolean
   context: TestContext & ExtraContext
   onFailed?: OnTestFailedHandler[]
+  /**
+   * Store promises (from async expects) to wait for them before finishing the test
+   */
+  promises?: Promise<any>[]
 }
 
 export type Task = Test | Suite | TaskCustom | File

packages/snapshot/src/client.ts

@@ -1,6 +1,7 @@
 import { deepMergeSnapshot } from './port/utils'
 import SnapshotState from './port/state'
 import type { SnapshotStateOptions } from './types'
+import type { RawSnapshotInfo } from './port/rawSnapshot'
 
 const createMismatchError = (message: string, actual: unknown, expected: unknown) => {
   const error = new Error(message)
@@ -35,6 +36,7 @@ interface AssertOptions {
   inlineSnapshot?: string
   error?: Error
   errorMessage?: string
+  rawSnapshot?: RawSnapshotInfo
 }
 
 export class SnapshotClient {
@@ -79,7 +81,7 @@ export class SnapshotClient {
   }
 
   /**
-   * Should be overriden by the consumer.
+   * Should be overridden by the consumer.
    *
    * Vitest checks equality with @vitest/expect.
    */
@@ -97,6 +99,7 @@ export class SnapshotClient {
       inlineSnapshot,
       error,
       errorMessage,
+      rawSnapshot,
     } = options
     let { received } = options
 
@@ -134,12 +137,38 @@ export class SnapshotClient {
       isInline,
       error,
       inlineSnapshot,
+      rawSnapshot,
     })
 
     if (!pass)
       throw createMismatchError(`Snapshot \`${key || 'unknown'}\` mismatched`, actual?.trim(), expected?.trim())
   }
 
+  async assertRaw(options: AssertOptions): Promise<void> {
+    if (!options.rawSnapshot)
+      throw new Error('Raw snapshot is required')
+
+    const {
+      filepath = this.filepath,
+      rawSnapshot,
+    } = options
+
+    if (rawSnapshot.content == null) {
+      if (!filepath)
+        throw new Error('Snapshot cannot be used outside of test')
+
+      const snapshotState = this.getSnapshotState(filepath)
+
+      // save the filepath, so it don't lose even if the await make it out-of-context
+      options.filepath ||= filepath
+      // resolve and read the raw snapshot file
+      rawSnapshot.file = await snapshotState.environment.resolveRawPath(filepath, rawSnapshot.file)
+      rawSnapshot.content = await snapshotState.environment.readSnapshotFile(rawSnapshot.file) || undefined
+    }
+
+    return this.assert(options)
+  }
+
   async resetCurrent() {
     if (!this.snapshotState)
       return null

packages/snapshot/src/env/node.ts

@@ -1,5 +1,5 @@
 import { existsSync, promises as fs } from 'node:fs'
-import { basename, dirname, join } from 'pathe'
+import { basename, dirname, isAbsolute, join, resolve } from 'pathe'
 import type { SnapshotEnvironment } from '../types'
 
 export class NodeSnapshotEnvironment implements SnapshotEnvironment {
@@ -11,6 +11,12 @@ export class NodeSnapshotEnvironment implements SnapshotEnvironment {
     return `// Snapshot v${this.getVersion()}`
   }
 
+  async resolveRawPath(testPath: string, rawPath: string) {
+    return isAbsolute(rawPath)
+      ? rawPath
+      : resolve(dirname(testPath), rawPath)
+  }
+
   async resolvePath(filepath: string): Promise<string> {
     return join(
       join(

packages/snapshot/src/manager.ts

@@ -1,4 +1,4 @@
-import { basename, dirname, join } from 'pathe'
+import { basename, dirname, isAbsolute, join, resolve } from 'pathe'
 import type { SnapshotResult, SnapshotStateOptions, SnapshotSummary } from './types'
 
 export class SnapshotManager {
@@ -28,6 +28,12 @@ export class SnapshotManager {
 
     return resolver(testPath, this.extension)
   }
+
+  resolveRawPath(testPath: string, rawPath: string) {
+    return isAbsolute(rawPath)
+      ? rawPath
+      : resolve(dirname(testPath), rawPath)
+  }
 }
 
 export function emptySummary(options: Omit<SnapshotStateOptions, 'snapshotEnvironment'>): SnapshotSummary {

packages/snapshot/src/port/rawSnapshot.ts

@@ -0,0 +1,22 @@
+import type { SnapshotEnvironment } from '../types'
+
+export interface RawSnapshotInfo {
+  file: string
+  readonly?: boolean
+  content?: string
+}
+
+export interface RawSnapshot extends RawSnapshotInfo {
+  snapshot: string
+  file: string
+}
+
+export async function saveRawSnapshots(
+  environment: SnapshotEnvironment,
+  snapshots: Array<RawSnapshot>,
+) {
+  await Promise.all(snapshots.map(async (snap) => {
+    if (!snap.readonly)
+      await environment.saveSnapshotFile(snap.file, snap.snapshot)
+  }))
+}

packages/snapshot/src/port/state.ts

@@ -11,6 +11,8 @@ import type { OptionsReceived as PrettyFormatOptions } from 'pretty-format'
 import type { SnapshotData, SnapshotEnvironment, SnapshotMatchOptions, SnapshotResult, SnapshotStateOptions, SnapshotUpdateState } from '../types'
 import type { InlineSnapshot } from './inlineSnapshot'
 import { saveInlineSnapshots } from './inlineSnapshot'
+import type { RawSnapshot, RawSnapshotInfo } from './rawSnapshot'
+import { saveRawSnapshots } from './rawSnapshot'
 
 import {
   addExtraLineBreaks,
@@ -43,6 +45,7 @@ export default class SnapshotState {
   private _snapshotData: SnapshotData
   private _initialData: SnapshotData
   private _inlineSnapshots: Array<InlineSnapshot>
+  private _rawSnapshots: Array<RawSnapshot>
   private _uncheckedKeys: Set<string>
   private _snapshotFormat: PrettyFormatOptions
   private _environment: SnapshotEnvironment
@@ -69,6 +72,7 @@ export default class SnapshotState {
     this._snapshotData = data
     this._dirty = dirty
     this._inlineSnapshots = []
+    this._rawSnapshots = []
     this._uncheckedKeys = new Set(Object.keys(this._snapshotData))
     this._counters = new Map()
     this.expand = options.expand || false
@@ -93,6 +97,10 @@ export default class SnapshotState {
     return new SnapshotState(testFilePath, snapshotPath, content, options)
   }
 
+  get environment() {
+    return this._environment
+  }
+
   markSnapshotsAsCheckedForTest(testName: string): void {
     this._uncheckedKeys.forEach((uncheckedKey) => {
       if (keyToTestName(uncheckedKey) === testName)
@@ -115,7 +123,7 @@ export default class SnapshotState {
   private _addSnapshot(
     key: string,
     receivedSerialized: string,
-    options: { isInline: boolean; error?: Error },
+    options: { isInline: boolean; rawSnapshot?: RawSnapshotInfo; error?: Error },
   ): void {
     this._dirty = true
     if (options.isInline) {
@@ -135,6 +143,12 @@ export default class SnapshotState {
         ...stack,
       })
     }
+    else if (options.rawSnapshot) {
+      this._rawSnapshots.push({
+        ...options.rawSnapshot,
+        snapshot: receivedSerialized,
+      })
+    }
     else {
       this._snapshotData[key] = receivedSerialized
     }
@@ -154,7 +168,8 @@ export default class SnapshotState {
   async save(): Promise<SaveStatus> {
     const hasExternalSnapshots = Object.keys(this._snapshotData).length
     const hasInlineSnapshots = this._inlineSnapshots.length
-    const isEmpty = !hasExternalSnapshots && !hasInlineSnapshots
+    const hasRawSnapshots = this._rawSnapshots.length
+    const isEmpty = !hasExternalSnapshots && !hasInlineSnapshots && !hasRawSnapshots
 
     const status: SaveStatus = {
       deleted: false,
@@ -168,6 +183,8 @@ export default class SnapshotState {
       }
       if (hasInlineSnapshots)
         await saveInlineSnapshots(this._environment, this._inlineSnapshots)
+      if (hasRawSnapshots)
+        await saveRawSnapshots(this._environment, this._rawSnapshots)
 
       status.saved = true
     }
@@ -206,6 +223,7 @@ export default class SnapshotState {
     inlineSnapshot,
     isInline,
     error,
+    rawSnapshot,
   }: SnapshotMatchOptions): SnapshotReturnOptions {
     this._counters.set(testName, (this._counters.get(testName) || 0) + 1)
     const count = Number(this._counters.get(testName))
@@ -219,14 +237,24 @@ export default class SnapshotState {
     if (!(isInline && this._snapshotData[key] !== undefined))
       this._uncheckedKeys.delete(key)
 
-    const receivedSerialized = addExtraLineBreaks(serialize(received, undefined, this._snapshotFormat))
-    const expected = isInline ? inlineSnapshot : this._snapshotData[key]
+    let receivedSerialized = rawSnapshot && typeof received === 'string'
+      ? received as string
+      : serialize(received, undefined, this._snapshotFormat)
+
+    if (!rawSnapshot)
+      receivedSerialized = addExtraLineBreaks(receivedSerialized)
+
+    const expected = isInline
+      ? inlineSnapshot
+      : rawSnapshot
+        ? rawSnapshot.content
+        : this._snapshotData[key]
     const expectedTrimmed = prepareExpected(expected)
     const pass = expectedTrimmed === prepareExpected(receivedSerialized)
     const hasSnapshot = expected !== undefined
-    const snapshotIsPersisted = isInline || this._fileExists
+    const snapshotIsPersisted = isInline || this._fileExists || (rawSnapshot && rawSnapshot.content != null)
 
-    if (pass && !isInline) {
+    if (pass && !isInline && !rawSnapshot) {
       // Executing a snapshot file as JavaScript and writing the strings back
       // when other snapshots have changed loses the proper escaping for some
       // characters. Since we check every snapshot in every test, use the newly
@@ -255,14 +283,14 @@ export default class SnapshotState {
           else
             this.added++
 
-          this._addSnapshot(key, receivedSerialized, { error, isInline })
+          this._addSnapshot(key, receivedSerialized, { error, isInline, rawSnapshot })
         }
         else {
           this.matched++
         }
       }
       else {
-        this._addSnapshot(key, receivedSerialized, { error, isInline })
+        this._addSnapshot(key, receivedSerialized, { error, isInline, rawSnapshot })
         this.added++
       }
 

packages/snapshot/src/port/utils.ts

@@ -163,6 +163,24 @@ export async function saveSnapshotFile(
   )
 }
 
+export async function saveSnapshotFileRaw(
+  environment: SnapshotEnvironment,
+  content: string,
+  snapshotPath: string,
+) {
+  const oldContent = await environment.readSnapshotFile(snapshotPath)
+  const skipWriting = oldContent && oldContent === content
+
+  if (skipWriting)
+    return
+
+  await ensureDirectoryExists(environment, snapshotPath)
+  await environment.saveSnapshotFile(
+    snapshotPath,
+    content,
+  )
+}
+
 export function prepareExpected(expected?: string) {
   function findStartIndent() {
     // Attempts to find indentation for objects.

packages/snapshot/src/types/environment.ts

@@ -2,6 +2,7 @@ export interface SnapshotEnvironment {
   getVersion(): string
   getHeader(): string
   resolvePath(filepath: string): Promise<string>
+  resolveRawPath(testPath: string, rawPath: string): Promise<string>
   prepareDirectory(filepath: string): Promise<void>
   saveSnapshotFile(filepath: string, snapshot: string): Promise<void>
   readSnapshotFile(filepath: string): Promise<string | null>

packages/snapshot/src/types/index.ts

@@ -1,4 +1,5 @@
 import type { OptionsReceived as PrettyFormatOptions } from 'pretty-format'
+import type { RawSnapshotInfo } from '../port/rawSnapshot'
 import type { SnapshotEnvironment } from './environment'
 
 export type { SnapshotEnvironment }
@@ -21,6 +22,7 @@ export interface SnapshotMatchOptions {
   inlineSnapshot?: string
   isInline: boolean
   error?: Error
+  rawSnapshot?: RawSnapshotInfo
 }
 
 export interface SnapshotResult {

packages/vitest/src/api/setup.ts

@@ -61,6 +61,9 @@ export function setup(ctx: Vitest, server?: ViteDevServer) {
         resolveSnapshotPath(testPath) {
           return ctx.snapshot.resolvePath(testPath)
         },
+        resolveSnapshotRawPath(testPath, rawPath) {
+          return ctx.snapshot.resolveRawPath(testPath, rawPath)
+        },
         removeFile(id) {
           return fs.unlink(id)
         },

packages/vitest/src/api/types.ts

@@ -15,6 +15,7 @@ export interface WebSocketHandlers {
   getPaths(): string[]
   getConfig(): ResolvedConfig
   resolveSnapshotPath(testPath: string): string
+  resolveSnapshotRawPath(testPath: string, rawPath: string): string
   getModuleGraph(id: string): Promise<ModuleGraphData>
   getTransformResult(id: string): Promise<TransformResultWithSource | undefined>
   readFile(id: string): Promise<string | null>

packages/vitest/src/integrations/chai/index.ts

@@ -1,6 +1,7 @@
 import * as chai from 'chai'
 import './setup'
 import type { Test } from '@vitest/runner'
+import { getCurrentTest } from '@vitest/runner'
 import { GLOBAL_EXPECT, getState, setState } from '@vitest/expect'
 import type { MatcherState } from '../../types/chai'
 import { getCurrentEnvironment, getFullName } from '../../utils'
@@ -10,9 +11,10 @@ export function createExpect(test?: Test) {
     const { assertionCalls } = getState(expect)
     setState({ assertionCalls: assertionCalls + 1 }, expect)
     const assert = chai.expect(value, message) as unknown as Vi.Assertion
-    if (test)
+    const _test = test || getCurrentTest()
+    if (_test)
       // @ts-expect-error internal
-      return assert.withTest(test) as Vi.Assertion
+      return assert.withTest(_test) as Vi.Assertion
     else
       return assert
   }) as Vi.ExpectStatic

packages/vitest/src/integrations/snapshot/chai.ts

@@ -3,6 +3,7 @@ import type { Test } from '@vitest/runner'
 import { getNames } from '@vitest/runner/utils'
 import type { SnapshotClient } from '@vitest/snapshot'
 import { addSerializer, stripSnapshotIndentation } from '@vitest/snapshot'
+import { recordAsyncExpect } from '../../../../expect/src/utils'
 import { VitestSnapshotClient } from './client'
 
 let _client: SnapshotClient
@@ -72,6 +73,30 @@ export const SnapshotPlugin: ChaiPlugin = (chai, utils) => {
       },
     )
   }
+
+  utils.addMethod(
+    chai.Assertion.prototype,
+    'toMatchFileSnapshot',
+    function (this: Record<string, unknown>, file: string, message?: string) {
+      const expected = utils.flag(this, 'object')
+      const test = utils.flag(this, 'vitest-test') as Test
+      const errorMessage = utils.flag(this, 'message')
+
+      const promise = getSnapshotClient().assertRaw({
+        received: expected,
+        message,
+        isInline: false,
+        rawSnapshot: {
+          file,
+        },
+        errorMessage,
+        ...getTestNames(test),
+      })
+
+      return recordAsyncExpect(test, promise)
+    },
+  )
+
   utils.addMethod(
     chai.Assertion.prototype,
     'toMatchInlineSnapshot',

packages/vitest/src/types/global.ts

@@ -66,12 +66,13 @@ declare global {
 
     interface JestAssertion<T = any> extends jest.Matchers<void, T> {
       // Snapshot
-      toMatchSnapshot<U extends { [P in keyof T]: any }>(snapshot: Partial<U>, message?: string): void
-      toMatchSnapshot(message?: string): void
       matchSnapshot<U extends { [P in keyof T]: any }>(snapshot: Partial<U>, message?: string): void
       matchSnapshot(message?: string): void
+      toMatchSnapshot<U extends { [P in keyof T]: any }>(snapshot: Partial<U>, message?: string): void
+      toMatchSnapshot(message?: string): void
       toMatchInlineSnapshot<U extends { [P in keyof T]: any }>(properties: Partial<U>, snapshot?: string, message?: string): void
       toMatchInlineSnapshot(snapshot?: string, message?: string): void
+      toMatchFileSnapshot(filepath: string, message?: string): Promise<void>
       toThrowErrorMatchingSnapshot(message?: string): void
       toThrowErrorMatchingInlineSnapshot(snapshot?: string, message?: string): void
 

test/core/test/jest-expect.test.ts

@@ -544,15 +544,15 @@ describe('async expect', () => {
     })()).resolves.not.toThrow(Error)
   })
 
-  it('resolves trows chai', async () => {
+  it('resolves throws chai', async () => {
     const assertion = async () => {
       await expect((async () => new Error('msg'))()).resolves.toThrow()
     }
 
     await expect(assertion).rejects.toThrowError('expected promise to throw an error, but it didn\'t')
   })
 
-  it('resolves trows jest', async () => {
+  it('resolves throws jest', async () => {
     const assertion = async () => {
       await expect((async () => new Error('msg'))()).resolves.toThrow(Error)
     }
@@ -679,6 +679,31 @@ describe('async expect', () => {
       expect(error).toEqual(toEqualError2)
     }
   })
+
+  describe('promise auto queuing', () => {
+    it.fails('fails', () => {
+      expect(() => new Promise((resolve, reject) => setTimeout(reject, 500)))
+        .resolves
+        .toBe('true')
+    })
+
+    let value = 0
+
+    it('pass first', () => {
+      expect((async () => {
+        await new Promise(resolve => setTimeout(resolve, 500))
+        value += 1
+        return value
+      })())
+        .resolves
+        .toBe(1)
+    })
+
+    it('pass second', () => {
+    // even if 'pass first' is sync, we will still wait the expect to resolve
+      expect(value).toBe(1)
+    })
+  })
 })
 
 it('compatible with jest', () => {

test/snapshots/test/fixtures/basic/input.json

@@ -0,0 +1,8 @@
+[
+  [
+    ".name",
+    {
+      "color": "red"
+    }
+  ]
+]

test/snapshots/test/fixtures/basic/output.css

@@ -0,0 +1,3 @@
+.name {
+  color: red;
+}

test/snapshots/test/fixtures/multiple/input.json

@@ -0,0 +1,15 @@
+[
+  [
+    ".text-red",
+    {
+      "color": "red"
+    }
+  ],
+  [
+    ".text-lg",
+    {
+      "font-size": "1.25rem",
+      "line-height": "1.75rem"
+    }
+  ]
+]

test/snapshots/test/fixtures/multiple/output.css

@@ -0,0 +1,7 @@
+.text-red {
+  color: red;
+}
+.text-lg {
+  font-size: 1.25rem;
+  line-height: 1.75rem;
+}

test/snapshots/test/shapshots-file.test.ts

@@ -0,0 +1,20 @@
+import { expect, test } from 'vitest'
+
+function objectToCSS(selector: string, obj: Record<string, string>) {
+  const body = Object.entries(obj)
+    .map(([key, value]) => `  ${key}: ${value};`)
+    .join('\n')
+  return `${selector} {\n${body}\n}`
+}
+
+describe('snapshots', () => {
+  const files = import.meta.glob('./fixtures/**/input.json', { as: 'raw' })
+
+  for (const [path, file] of Object.entries(files)) {
+    test(path, async () => {
+      const entries = JSON.parse(await file()) as any[]
+      expect(entries.map(i => objectToCSS(i[0], i[1])).join('\n'))
+        .toMatchFileSnapshot(path.replace('input.json', 'output.css'))
+    })
+  }
+})