From a96d2068f347606950fec7a46c501d27b97e2bc5 Mon Sep 17 00:00:00 2001
From: Rob Hogan <robhogan@meta.com>
Date: Fri, 11 Jul 2025 14:18:27 -0700
Subject: [PATCH] Replace metro-memory-fs dependency in tests with OSS memfs
 (#52572)

Summary:

We'd like to stop supporting `metro-memory-fs` - there are better alternatives out there.

This replaces the one usage of `metro-memory-fs` in `react-native` with `memfs`, and swaps the dependency.

Changelog: [Internal]

Reviewed By: vzaidman

Differential Revision: D78161921
---
 package.json                                  |  2 +-
 .../hermes/__tests__/hermes-utils-test.js     | 17 +++++++----------
 yarn.lock                                     | 19 ++++++++++++-------
 3 files changed, 20 insertions(+), 18 deletions(-)

diff --git a/package.json b/package.json
index d9659229a9d..13cdb9fd3cf 100644
--- a/package.json
+++ b/package.json
@@ -93,8 +93,8 @@
     "jest-snapshot": "^29.7.0",
     "markdownlint-cli2": "^0.17.2",
     "markdownlint-rule-relative-links": "^3.0.0",
+    "memfs": "^4.7.7",
     "metro-babel-register": "^0.82.5",
-    "metro-memory-fs": "^0.82.5",
     "metro-transform-plugins": "^0.82.5",
     "micromatch": "^4.0.4",
     "node-fetch": "^2.2.0",
diff --git a/packages/react-native/scripts/hermes/__tests__/hermes-utils-test.js b/packages/react-native/scripts/hermes/__tests__/hermes-utils-test.js
index d735445b071..63d6ff59ea7 100644
--- a/packages/react-native/scripts/hermes/__tests__/hermes-utils-test.js
+++ b/packages/react-native/scripts/hermes/__tests__/hermes-utils-test.js
@@ -8,6 +8,8 @@
  * @format
  */
 
+import typeof FS from 'fs';
+
 import * as path from 'path';
 
 const {
@@ -25,9 +27,12 @@ const {
   setHermesTag,
   shouldUsePrebuiltHermesC,
 } = require('../hermes-utils');
-const MemoryFs = require('metro-memory-fs');
 const os = require('os');
 
+// $FlowFixMe[untyped-import] (OSS) memfs
+// $FlowFixMe[cannot-resolve-module] (Meta) memfs
+const {memfs} = require('memfs') as {memfs: () => {fs: FS}};
+
 const hermesTag =
   'hermes-2022-04-28-RNv0.69.0-15d07c2edd29a4ea0b8f15ab0588a0c1adb1200f';
 const tarballContents = 'dummy string';
@@ -147,16 +152,8 @@ describe('hermes-utils', () => {
   beforeEach(() => {
     jest.resetModules();
 
-    jest.mock(
-      'fs',
-      () =>
-        new MemoryFs({
-          platform: process.platform === 'win32' ? 'win32' : 'posix',
-        }),
-    );
+    jest.mock('fs', () => memfs().fs);
     fs = require('fs');
-    // $FlowFixMe[prop-missing]
-    fs.reset();
 
     populateMockFilesystemWithHermesBuildScripts();
 
diff --git a/yarn.lock b/yarn.lock
index 161363b4a85..0e09a0d0d3e 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -6823,6 +6823,13 @@ memfs-or-file-map-to-github-branch@^1.3.0:
   dependencies:
     "@octokit/rest" "*"
 
+memfs@^4.7.7:
+  version "4.7.7"
+  resolved "https://registry.yarnpkg.com/memfs/-/memfs-4.7.7.tgz#bcf09cab1646d655f659e7cf832dfc75ccb95b2d"
+  integrity sha512-x9qc6k88J/VVwnfTkJV8pRRswJ2156Rc4w5rciRqKceFDZ0y1MqsNL9pkg5sE0GOcDzZYbonreALhaHzg1siFw==
+  dependencies:
+    tslib "^2.0.0"
+
 memoize-one@^5.0.0:
   version "5.2.1"
   resolved "https://registry.yarnpkg.com/memoize-one/-/memoize-one-5.2.1.tgz#8337aa3c4335581839ec01c3d594090cebe8f00e"
@@ -6920,13 +6927,6 @@ metro-file-map@0.82.5:
     nullthrows "^1.1.1"
     walker "^1.0.7"
 
-metro-memory-fs@^0.82.5:
-  version "0.82.5"
-  resolved "https://registry.yarnpkg.com/metro-memory-fs/-/metro-memory-fs-0.82.5.tgz#ae6c4c251cd6dc9cf44540c3b1356cff54db875e"
-  integrity sha512-yMYtBwDtG84vnDfQDEGZ3EUYbHng4dMZX2AKSQFQOMdd34lyQcD1yV5yrrUTG/DqMKDxJGqmxDkeyqTlKwwuUA==
-  dependencies:
-    flow-enums-runtime "^0.0.6"
-
 metro-minify-terser@0.82.5:
   version "0.82.5"
   resolved "https://registry.yarnpkg.com/metro-minify-terser/-/metro-minify-terser-0.82.5.tgz#5dc77d53b6ef4079bd9c752ae046d557df4ae584"
@@ -9191,6 +9191,11 @@ tslib@^1.8.1, tslib@^1.9.0:
   resolved "https://registry.yarnpkg.com/tslib/-/tslib-1.14.1.tgz#cf2d38bdc34a134bcaf1091c41f6619e2f672d00"
   integrity sha512-Xni35NKzjgMrwevysHTCArtLDpPvye8zV/0E4EyYn43P7/7qvQwPh9BGkHewbMulVntbigmcT7rdX3BNo9wRJg==
 
+tslib@^2.0.0:
+  version "2.8.1"
+  resolved "https://registry.yarnpkg.com/tslib/-/tslib-2.8.1.tgz#612efe4ed235d567e8aba5f2a5fab70280ade83f"
+  integrity sha512-oJFu94HQb+KVduSUQL7wnpmqnfmLsOA/nAh6b6EH0wCEoK0/mPeXU6c3wKDV83MkOuHPRHtSXKKU99IBazS/2w==
+
 tslib@^2.1.0:
   version "2.7.0"
   resolved "https://registry.yarnpkg.com/tslib/-/tslib-2.7.0.tgz#d9b40c5c40ab59e8738f297df3087bf1a2690c01"