hmm

CHANGELOG.md

@@ -8,6 +8,8 @@
 
 ### Performance
 
+- `[jest-resolve]` Skip expensive error creation on not found stat calls. [#11749](https://github.com/facebook/jest/pull/11749)
+
 ## 27.0.7
 
 ### Chore & Maintenance

packages/jest-resolve/src/__tests__/resolve.test.ts

@@ -11,7 +11,7 @@ import * as fs from 'graceful-fs';
 import {sync as resolveSync} from 'resolve';
 import {ModuleMap} from 'jest-haste-map';
 import userResolver from '../__mocks__/userResolver';
-import defaultResolver from '../defaultResolver';
+import defaultResolver, {ResolverOptions} from '../defaultResolver';
 import nodeModulesPaths from '../nodeModulesPaths';
 import Resolver from '../resolver';
 import type {ResolverConfig} from '../types';
@@ -323,3 +323,11 @@ describe('Resolver.getModulePaths() -> nodeModulesPaths()', () => {
     expect(dirs_actual).toEqual(expect.arrayContaining(dirs_expected));
   });
 });
+
+describe('defaultResolver', () => {
+  it('does not change outwardly stackTraceLimit', () => {
+    const oldStackTraceValue = Error.stackTraceLimit;
+    expect(() => defaultResolver('test', {} as ResolverOptions)).toThrow();
+    expect(oldStackTraceValue).toBe(Error.stackTraceLimit);
+  });
+});

packages/jest-resolve/src/defaultResolver.ts

@@ -11,7 +11,7 @@ import {sync as resolveSync} from 'resolve';
 import type {Config} from '@jest/types';
 import {tryRealpath} from 'jest-util';
 
-type ResolverOptions = {
+export type ResolverOptions = {
   basedir: Config.Path;
   browser?: boolean;
   defaultResolver: typeof defaultResolver;
@@ -78,12 +78,21 @@ function statSyncCached(path: string): IPathType {
   }
 
   let stat;
+  const oldTrace = Object.getOwnPropertyDescriptors(Error).stackTraceLimit;
   try {
+    if(oldTrace.writable) {
+      Object.defineProperty(Error, 'stackTraceLimit', {
+        value: 0,
+        writable: false,
+      });
+    }
     stat = fs.statSync(path);
   } catch (e) {
     if (!(e && (e.code === 'ENOENT' || e.code === 'ENOTDIR'))) {
       throw e;
     }
+  } finally {
+    Object.defineProperty(Error, 'stackTraceLimit', oldTrace);
   }
 
   if (stat) {