feat: add diff.maxDepth option and set non-Infinity value as a default to reduce crash (#7481)

Author: hi-ogawa

docs/config/index.md

@@ -2331,6 +2331,13 @@ Color of truncate annotation, default is output with no color.
 
 Print basic prototype `Object` and `Array` in diff output
 
+#### diff.maxDepth
+
+- **Type**: `number`
+- **Default**: `20` (or `8` when comparing different types)
+
+Limit the depth to recurse when printing nested objects
+
 ### fakeTimers
 
 - **Type:** `FakeTimerInstallOpts`

packages/utils/src/diff/index.ts

@@ -53,13 +53,14 @@ const PLUGINS = [
   prettyFormatPlugins.Error,
 ]
 const FORMAT_OPTIONS = {
+  maxDepth: 20,
   plugins: PLUGINS,
-}
+} satisfies PrettyFormatOptions
 const FALLBACK_FORMAT_OPTIONS = {
   callToJSON: false,
   maxDepth: 8,
   plugins: PLUGINS,
-}
+} satisfies PrettyFormatOptions
 
 // Generate a string that will highlight the difference between two values
 // with green and red. (similar to how github does code diffing)
@@ -191,12 +192,13 @@ function getFormatOptions(
   formatOptions: PrettyFormatOptions,
   options?: DiffOptions,
 ): PrettyFormatOptions {
-  const { compareKeys, printBasicPrototype } = normalizeDiffOptions(options)
+  const { compareKeys, printBasicPrototype, maxDepth } = normalizeDiffOptions(options)
 
   return {
     ...formatOptions,
     compareKeys,
     printBasicPrototype,
+    maxDepth: maxDepth ?? formatOptions.maxDepth,
   }
 }
 

packages/utils/src/diff/types.ts

@@ -27,6 +27,7 @@ export interface DiffOptions {
   omitAnnotationLines?: boolean
   patchColor?: DiffOptionsColor
   printBasicPrototype?: boolean
+  maxDepth?: number
   compareKeys?: CompareKeys
   truncateThreshold?: number
   truncateAnnotation?: string
@@ -45,6 +46,7 @@ export interface SerializedDiffOptions {
   includeChangeCounts?: boolean
   omitAnnotationLines?: boolean
   printBasicPrototype?: boolean
+  maxDepth?: number
   truncateThreshold?: number
   truncateAnnotation?: string
 }
@@ -69,6 +71,7 @@ export interface DiffOptionsNormalized {
   omitAnnotationLines: boolean
   patchColor: DiffOptionsColor
   printBasicPrototype: boolean
+  maxDepth?: number
   truncateThreshold: number
   truncateAnnotation: string
   truncateAnnotationColor: DiffOptionsColor

packages/vitest/src/node/cli/cli-config.ts

@@ -648,6 +648,10 @@ export const cliOptionsConfig: VitestCLIOptions = {
       printBasicPrototype: {
         description: 'Print basic prototype Object and Array (default: `true`)',
       },
+      maxDepth: {
+        description: 'Limit the depth to recurse when printing nested objects (default: `20`)',
+        argument: '<maxDepth>',
+      },
       truncateThreshold: {
         description: 'Number of lines to show before and after each change (default: `0`)',
         argument: '<threshold>',

test/core/test/diff.test.ts

@@ -324,6 +324,25 @@ test('truncate large diff', () => {
   expect(diff.trim()).toMatch(/\.\.\.$/)
 })
 
+test('diff default maxDepth', () => {
+  function generateCycle(n: number) {
+    const nodes = Array.from({ length: n }, (_, i) => ({ i, next: null as any }))
+    nodes.forEach((node, i) => {
+      node.next = nodes[(i + 1) % n]
+    })
+    return nodes
+  }
+
+  // diff only appears in a deeper depth than maxDepth
+  const xs = generateCycle(20)
+  const ys = generateCycle(20)
+  ys[10].i = -1
+  const diff = getErrorDiff(xs[0], ys[0], { maxDepth: 5 })
+  expect(stripVTControlCharacters(diff)).toMatchInlineSnapshot(
+    `"Compared values have no visual difference."`,
+  )
+})
+
 function getErrorDiff(actual: unknown, expected: unknown, options?: DiffOptions): string {
   try {
     expect(actual).toEqual(expected)