fix: support snapshot with no object key sorting (#8136)

hi-ogawa · sheremet-va · web-flow · commit e85e396f004f · 2025-07-14T15:11:35.000+02:00
Co-authored-by: Vladimir &lt;sleuths.slews0s@icloud.com&gt;
diff --git a/packages/pretty-format/src/types.ts b/packages/pretty-format/src/types.ts
@@ -24,6 +24,9 @@ export type Theme = Required<{
   value?: string
 }>
 
+/**
+ * compare function used when sorting object keys, `null` can be used to skip over sorting.
+ */
 export type CompareKeys = ((a: string, b: string) => number) | null | undefined
 
 type RequiredOptions = Required<PrettyFormatOptions>
diff --git a/packages/vitest/src/node/config/resolveConfig.ts b/packages/vitest/src/node/config/resolveConfig.ts
@@ -489,6 +489,10 @@ export function resolveConfig(
 
   if (resolved.snapshotFormat && 'plugins' in resolved.snapshotFormat) {
     (resolved.snapshotFormat as any).plugins = []
+    // TODO: support it via separate config (like DiffOptions) or via `Function.toString()`
+    if (typeof resolved.snapshotFormat.compareKeys === 'function') {
+      throw new TypeError(`"snapshotFormat.compareKeys" function is not supported.`)
+    }
   }
 
   const UPDATE_SNAPSHOT = resolved.update || process.env.UPDATE_SNAPSHOT
diff --git a/packages/vitest/src/node/config/serializeConfig.ts b/packages/vitest/src/node/config/serializeConfig.ts
@@ -120,7 +120,6 @@ export function serializeConfig(
       updateSnapshot: coreConfig.snapshotOptions.updateSnapshot,
       snapshotFormat: {
         ...coreConfig.snapshotOptions.snapshotFormat,
-        compareKeys: undefined,
       },
       expand:
         config.snapshotOptions.expand
diff --git a/packages/vitest/src/node/types/config.ts b/packages/vitest/src/node/types/config.ts
@@ -568,7 +568,9 @@ export interface InlineConfig {
   /**
    * Format options for snapshot testing.
    */
-  snapshotFormat?: Omit<PrettyFormatOptions, 'plugins'>
+  snapshotFormat?: Omit<PrettyFormatOptions, 'plugins' | 'compareKeys'> & {
+    compareKeys?: null | undefined
+  }
 
   /**
    * Path to a module which has a default export of diff config.
diff --git a/test/snapshots/test/compare-keys.test.ts b/test/snapshots/test/compare-keys.test.ts
@@ -0,0 +1,85 @@
+import fs from 'node:fs'
+import { join } from 'node:path'
+import { expect, test } from 'vitest'
+import { runVitest } from '../../test-utils'
+
+test('compareKeys', async () => {
+  const root = join(import.meta.dirname, 'fixtures/compare-keys')
+  fs.rmSync(join(root, '__snapshots__'), { recursive: true, force: true })
+
+  // compareKeys null
+  let vitest = await runVitest({
+    root,
+    update: true,
+    snapshotFormat: {
+      compareKeys: null,
+    },
+  })
+  expect(vitest.stderr).toBe('')
+  expect(fs.readFileSync(join(root, '__snapshots__/basic.test.ts.snap'), 'utf-8')).toMatchInlineSnapshot(`
+    "// Vitest Snapshot v1, https://vitest.dev/guide/snapshot.html
+
+    exports[\`compareKeys 1\`] = \`
+    {
+      "a": 1,
+      "b": 2,
+      "c": 3,
+    }
+    \`;
+
+    exports[\`compareKeys 2\`] = \`
+    {
+      "c": 1,
+      "b": 2,
+      "a": 3,
+    }
+    \`;
+
+    exports[\`compareKeys 3\`] = \`
+    {
+      "b": 1,
+      "a": 2,
+      "c": 3,
+    }
+    \`;
+    "
+  `)
+
+  // compareKeys undefined
+  vitest = await runVitest({
+    root,
+    update: true,
+    snapshotFormat: {
+      compareKeys: undefined,
+    },
+  })
+  expect(vitest.stderr).toBe('')
+  expect(fs.readFileSync(join(root, '__snapshots__/basic.test.ts.snap'), 'utf-8')).toMatchInlineSnapshot(`
+    "// Vitest Snapshot v1, https://vitest.dev/guide/snapshot.html
+
+    exports[\`compareKeys 1\`] = \`
+    {
+      "a": 1,
+      "b": 2,
+      "c": 3,
+    }
+    \`;
+
+    exports[\`compareKeys 2\`] = \`
+    {
+      "a": 3,
+      "b": 2,
+      "c": 1,
+    }
+    \`;
+
+    exports[\`compareKeys 3\`] = \`
+    {
+      "a": 2,
+      "b": 1,
+      "c": 3,
+    }
+    \`;
+    "
+  `)
+})
diff --git a/test/snapshots/test/fixtures/compare-keys/__snapshots__/basic.test.ts.snap b/test/snapshots/test/fixtures/compare-keys/__snapshots__/basic.test.ts.snap
@@ -0,0 +1,25 @@
+// Vitest Snapshot v1, https://vitest.dev/guide/snapshot.html
+
+exports[`compareKeys 1`] = `
+{
+  "a": 1,
+  "b": 2,
+  "c": 3,
+}
+`;
+
+exports[`compareKeys 2`] = `
+{
+  "a": 3,
+  "b": 2,
+  "c": 1,
+}
+`;
+
+exports[`compareKeys 3`] = `
+{
+  "a": 2,
+  "b": 1,
+  "c": 3,
+}
+`;
diff --git a/test/snapshots/test/fixtures/compare-keys/basic.test.ts b/test/snapshots/test/fixtures/compare-keys/basic.test.ts
@@ -0,0 +1,21 @@
+import { test, expect } from 'vitest';
+
+test('compareKeys', () => {
+  expect({
+    a: 1,
+    b: 2,
+    c: 3,
+  }).toMatchSnapshot();
+
+  expect({
+    c: 1,
+    b: 2,
+    a: 3,
+  }).toMatchSnapshot();
+
+  expect({
+    b: 1,
+    a: 2,
+    c: 3,
+  }).toMatchSnapshot();
+});
diff --git a/test/snapshots/test/fixtures/compare-keys/vitest.config.ts b/test/snapshots/test/fixtures/compare-keys/vitest.config.ts
@@ -0,0 +1,9 @@
+import { defineConfig } from "vitest/config";
+
+export default defineConfig({
+  test: {
+    snapshotFormat: {
+      // compareKeys: null,
+    }
+  }
+})

Original file line number	Diff line number	Diff line change
`@@ -489,6 +489,10 @@ export function resolveConfig(`
`489`	`489`
`490`	`490`	`if (resolved.snapshotFormat && 'plugins' in resolved.snapshotFormat) {`
`491`	`491`	`(resolved.snapshotFormat as any).plugins = []`
	`492`	+ // TODO: support it via separate config (like DiffOptions) or via `Function.toString()`
	`493`	`+ if (typeof resolved.snapshotFormat.compareKeys === 'function') {`
	`494`	+ throw new TypeError(`"snapshotFormat.compareKeys" function is not supported.`)
	`495`	`+ }`
`492`	`496`	`}`
`493`	`497`
`494`	`498`	`const UPDATE_SNAPSHOT = resolved.update \|\| process.env.UPDATE_SNAPSHOT`