fix: invalidate cache when fixture is updated via writeFile (#32161)

* fix: invalidate cache when fixture is updated via writeFile

* refactor: delete space

* fix: improve fixture path resolution

* fix: improve fixture path resolution

* fix: update cache key generation

* fix: fetch config at execution time

* fix: invalidate fixture cache entries across encodings and paths

* fix optimized dependencies failures

* fix: relative pathing on windows as path polyfill only works with unix style paths

* Update packages/driver/src/cy/commands/fixtures.ts

---------

Co-authored-by: Jennifer Shehane <[email protected]>
Co-authored-by: Bill Glesias <[email protected]>

Author: 3 people

.eslintrc.js

@@ -42,6 +42,8 @@ module.exports = {
     'npm/eslint-plugin-dev/test/fixtures/**',
     // Cloud generated
     'system-tests/lib/validations/**',
+    // ignore as the file has invalid syntax
+    'system-tests/projects/no-specs-babel-conflict/src/Invalid.jsx',
   ],
   overrides: [
     {

cli/CHANGELOG.md

@@ -37,6 +37,7 @@ _Released 08/12/2025 (PENDING)_
 - Fixed an issue where `isSecureContext` would be `false` on localhost when testing with Cypress. Addresses [#18217](https://github.com/cypress-io/cypress/issues/18217).
 - Fixed an issue where Angular legacy `Output()` decorators were broken when making component instance field references safe. Fixes [#32137](https://github.com/cypress-io/cypress/issues/32137).
 - Upgraded `tmp` from `~0.2.3` to `~0.2.4`. This removes the [CVE-2025-54798](https://github.com/advisories/GHSA-52f5-9888-hmc6) vulnerability being reported in security scans. Addresses [#32176](https://github.com/cypress-io/cypress/issues/32176).
+- Fixed an issue where `.fixture()` would not return updated content after the underlying file was modified via `.writeFile()`. The fixture cache is now properly invalidated when the backing file is written to, ensuring updated content is returned in subsequent `.fixture()` calls. Fixes [#4716](https://github.com/cypress-io/cypress/issues/4716).
 - Fixed an issue where `.fixture()` calls with a specified encoding would sometimes still attempt to parse the file based on its extension. Files with an explicit encoding are now always treated as raw content. Fixes [#32139](https://github.com/cypress-io/cypress/issues/32139).
 - Fixed an issue where `.fixture()` calls with different encoding options would return inconsistent content based on execution order. Fixes [#32138](https://github.com/cypress-io/cypress/issues/32138).
 - Fixed an issue where Angular Component Testing was printing extraneous warnings to the console by default. By default, errors only will now print to the console. This can still be overridden by passing in a custom webpack config or setting the `verbose` option inside your `angular.json`. Addresses [#26456](https://github.com/cypress-io/cypress/issues/26456).

packages/app/vite.config.mjs

@@ -22,6 +22,7 @@ const config = makeConfig({
       '@headlessui/vue',
       '@cypress-design/vue-icon',
       '@cypress-design/vue-statusicon',
+      '@module-federation/runtime',
       'human-interval',
       'floating-vue',
       'dayjs',
@@ -40,6 +41,7 @@ const config = makeConfig({
       '@opentelemetry/semantic-conventions',
       '@opentelemetry/exporter-trace-otlp-http',
       '@opentelemetry/core',
+      'semver/functions/major',
     ],
     esbuildOptions: {
       target: 'ES2022',

packages/driver/cypress/e2e/commands/fixtures.cy.js

@@ -3,6 +3,8 @@ const stripAnsi = require('strip-ansi')
 const { assertLogLength } = require('../../support/utils')
 const { Promise } = Cypress
 
+const { fixturesFolder } = Cypress.config()
+
 describe('src/cy/commands/fixtures', () => {
   beforeEach(() => {
     return Cypress.emit('clear:fixtures:cache')
@@ -266,6 +268,24 @@ describe('src/cy/commands/fixtures', () => {
         })
       })
 
+      it('should invalidate fixture cache entry when `writeFile` modifies the fixture', () => {
+        const fixtureBaseName = 'invalidate'
+        const filePath = `${fixturesFolder}/${fixtureBaseName}.json`
+        const contents = [
+          { scene: '🌸🌷🐝🦋🌱' },
+          { scene: '🌞🌊🕶️🍉🏖️' },
+          { scene: '🍁🎃🦃🌰🍎' },
+          { scene: '❄️⛄🎄🎁🦌' },
+        ]
+
+        contents.forEach((content, i) => {
+          const fixtureName = `${fixtureBaseName}${(i % 2) ? '.json' : ''}`
+
+          cy.writeFile(filePath, content)
+          cy.fixture(fixtureName).should('deep.equal', content)
+        })
+      })
+
       it('should respect encoding specification', () => {
         const fixture = 'comma-separated.csv'
 

packages/driver/src/cy/commands/files.ts

@@ -1,5 +1,5 @@
 import _ from 'lodash'
-import { basename } from 'path'
+import { basename, isAbsolute, relative, resolve } from 'path'
 
 import $errUtils from '../../cypress/error_utils'
 import type { Log } from '../../cypress/log'
@@ -157,6 +157,8 @@ export default (Commands, Cypress, cy, state) => {
 
   Commands.addAll({
     writeFile (fileName: string, contents: string, encoding: Cypress.Encodings | WriteFileOptions | undefined, userOptions: WriteFileOptions, ...extras: never[]) {
+      const { defaultCommandTimeout, fixturesFolder } = Cypress.config()
+
       if (_.isObject(encoding)) {
         userOptions = encoding
         encoding = undefined
@@ -173,7 +175,7 @@ export default (Commands, Cypress, cy, state) => {
         encoding: encoding === undefined ? 'utf8' : encoding,
         flag: userOptions.flag ? userOptions.flag : 'w',
         log: true,
-        timeout: Cypress.config('defaultCommandTimeout'),
+        timeout: defaultCommandTimeout,
       })
 
       const consoleProps = {}
@@ -225,6 +227,28 @@ export default (Commands, Cypress, cy, state) => {
         consoleProps['File Path'] = filePath
         consoleProps['Contents'] = contents
 
+        if (fixturesFolder !== false) {
+          const normalizePath = (path) => path.replace(/\\/g, '/')
+          const resolvedFixturesFolder = normalizePath(resolve(fixturesFolder))
+          const resolvedFilePath = normalizePath(resolve(filePath))
+          const relativePath = relative(resolvedFixturesFolder, resolvedFilePath)
+
+          // If `relativePath` does not start with ".." and is not equal to itself
+          // with a leading "..", then `filePath` is inside `fixturesFolder`.
+          const isInsideFixturesFolder =
+            relativePath && !relativePath.startsWith('..') && !isAbsolute(relativePath)
+
+          if (isInsideFixturesFolder) {
+            /**
+             * Relative path from the fixtures folder to the written file,
+             * normalized with forward slashes.
+             */
+            const fixtureName = relativePath.replace(/\\/g, '/')
+
+            Cypress.emit('fixture:cache:invalidate', fixtureName)
+          }
+        }
+
         return null
       })
       .catch((err) => {

packages/driver/src/cy/commands/fixtures.ts

@@ -1,9 +1,11 @@
 import _ from 'lodash'
 import Promise from 'bluebird'
-import { basename } from 'path'
+import { basename, extname, sep } from 'path'
 
 import $errUtils from '../../cypress/error_utils'
 
+const NULL_SEP = '\u0000'
+
 const clone = (obj) => {
   if (Buffer.isBuffer(obj)) {
     return Buffer.from(obj)
@@ -12,15 +14,73 @@ const clone = (obj) => {
   return JSON.parse(JSON.stringify(obj))
 }
 
+/**
+ * Given a path, returns an array containing the path with and without its extension.
+ * If there is no extension, returns an array containing only the original path.
+ *
+ * Used so invalidation can match both "foo.json" and "foo".
+ *
+ * @returns [pathWithExtension, pathWithoutExtension] if extension exists, otherwise [path].
+ */
+const withAndWithoutExt = (path: string) => {
+  const extension = extname(path)
+
+  return extension ? [path, path.slice(0, -extension.length)] : [path]
+}
+
+/**
+ * Builds path prefixes that might have been used in a cache key's fixture
+ * portion. Includes forward and backslash variants, with and without
+ * extensions, and lowercase variants on Windows.
+ */
+const buildPrefixes = (rawPath: string): string[] => {
+  const forward = rawPath.split(sep).join('/')
+  const backslash = forward.replace(/\//g, '\\')
+
+  const bases = [
+    ...withAndWithoutExt(forward),
+    ...withAndWithoutExt(backslash),
+  ]
+
+  if (Cypress.platform === 'win32') {
+    bases.push(
+      ...withAndWithoutExt(forward.toLowerCase()),
+      ...withAndWithoutExt(backslash.toLowerCase()),
+    )
+  }
+
+  return Array.from(new Set(bases))
+}
+
+/** Turn fixture path prefixes into matchable key prefixes. */
+const makeKeyPrefixes = (fixturePath: string): string[] => {
+  return buildPrefixes(fixturePath).map((prefix) => `${prefix}${NULL_SEP}`)
+}
+
 export default (Commands, Cypress, cy, state, config) => {
   // this is called at the beginning of run, so clear the cache
   let cache = {}
 
-  const reset = () => {
+  const clearCache = () => {
     cache = {}
   }
 
-  Cypress.on('clear:fixtures:cache', reset)
+  /**
+   * Removes all cached fixture entries that correspond to the given path,
+   * across all encodings.
+   */
+  const invalidateCacheEntry = (fixturePath: string) => {
+    const prefixes = makeKeyPrefixes(fixturePath)
+
+    for (const key of Object.keys(cache)) {
+      if (prefixes.some((prefix) => key.startsWith(prefix))) {
+        delete cache[key]
+      }
+    }
+  }
+
+  Cypress.on('clear:fixtures:cache', clearCache)
+  Cypress.on('fixture:cache:invalidate', invalidateCacheEntry)
 
   return Commands.addAll({
     fixture (fixture, ...args) {
@@ -40,7 +100,7 @@ export default (Commands, Cypress, cy, state, config) => {
         options.encoding = args[0]
       }
 
-      const cacheKey = `${fixture}\u0000${options.encoding || ''}`
+      const cacheKey = `${fixture}${NULL_SEP}${options.encoding || ''}`
       const cachedContent = cache[cacheKey]
 
       if (cachedContent) {

system-tests/projects/no-specs-babel-conflict/package.json

@@ -9,14 +9,14 @@
   },
   "devDependencies": {
     "@babel/core": "^7.12.0",
-    "babel-plugin-add-react-displayname": "^0.0.5",
     "@babel/plugin-proposal-class-properties": "^7.12.0",
     "@babel/plugin-proposal-decorators": "^7.12.0",
     "@babel/plugin-transform-react-jsx": "^7.12.0",
     "@babel/plugin-transform-runtime": "^7.12.0",
     "@babel/preset-env": "^7.12.0",
     "@babel/preset-react": "^7.12.0",
     "@babel/preset-typescript": "^7.12.0",
-    "@babel/runtime-corejs3": "^7.12.0"
+    "@babel/runtime-corejs3": "^7.12.0",
+    "babel-plugin-add-react-displayname": "^0.0.5"
   }
 }

system-tests/projects/no-specs-babel-conflict/src/Invalid.jsx

@@ -1,4 +1,4 @@
 import React from 'react'
 
-/*eslint-disable */
+/* eslint-disable */
 export function MyComponent (({