fix: make sure `atob` and `btoa` are writeable (#14446)

CHANGELOG.md

@@ -5,12 +5,15 @@
 ### Fixes
 
 - `[jest-core]` Fix typo in `scheduleAndRun` performance marker ([#14434](https://github.com/jestjs/jest/pull/14434))
+- `[jest-environment-node]` Make sure `atob` and `btoa` are writeable in Node 20 ([#14446](https://github.com/jestjs/jest/pull/14446))
 - `[jest-worker]` Additional error wrapper for `parentPort.postMessage` to fix unhandled `DataCloneError`. ([#14437](https://github.com/jestjs/jest/pull/14437))
 
 ### Chore & Maintenance
 
 ## 29.6.3
 
+### Fixes
+
 - `[expect, @jest/expect-utils]` `ObjectContaining` support `sumbol` as key ([#14414](https://github.com/jestjs/jest/pull/14414))
 - `[expect]` Remove `@types/node` from dependencies ([#14385](https://github.com/jestjs/jest/pull/14385))
 - `[jest-core]` Use workers in watch mode by default to avoid crashes ([#14059](https://github.com/facebook/jest/pull/14059) & [#14085](https://github.com/facebook/jest/pull/14085)).

e2e/override-globals/__tests__/index.js

@@ -27,4 +27,13 @@ describe('parent', () => {
       }, 10);
     });
   });
+
+  it('can override atob and btoa', () => {
+    // eslint-disable-next-line no-restricted-globals
+    global.atob = () => 'hello';
+    // eslint-disable-next-line no-restricted-globals
+    global.btoa = () => 'there';
+
+    expect(`${atob()} ${btoa()}`).toBe('hello there');
+  });
 });

packages/jest-environment-node/src/index.ts

@@ -27,6 +27,7 @@ const denyList = new Set([
   'GLOBAL',
   'root',
   'global',
+  'globalThis',
   'Buffer',
   'ArrayBuffer',
   'Uint8Array',
@@ -34,9 +35,11 @@ const denyList = new Set([
   'jest-symbol-do-not-touch',
 ]);
 
+type GlobalProperties = Array<keyof typeof globalThis>;
+
 const nodeGlobals = new Map(
-  Object.getOwnPropertyNames(globalThis)
-    .filter(global => !denyList.has(global))
+  (Object.getOwnPropertyNames(globalThis) as GlobalProperties)
+    .filter(global => !denyList.has(global as string))
     .map(nodeGlobalsKey => {
       const descriptor = Object.getOwnPropertyDescriptor(
         globalThis,
@@ -76,7 +79,9 @@ export default class NodeEnvironment implements JestEnvironment<Timer> {
     ) as Global.Global;
     this.global = global;
 
-    const contextGlobals = new Set(Object.getOwnPropertyNames(global));
+    const contextGlobals = new Set(
+      Object.getOwnPropertyNames(global) as GlobalProperties,
+    );
     for (const [nodeGlobalsKey, descriptor] of nodeGlobals) {
       if (!contextGlobals.has(nodeGlobalsKey)) {
         if (descriptor.configurable) {
@@ -84,27 +89,24 @@ export default class NodeEnvironment implements JestEnvironment<Timer> {
             configurable: true,
             enumerable: descriptor.enumerable,
             get() {
-              // @ts-expect-error: no index signature
-              const val = globalThis[nodeGlobalsKey] as unknown;
+              const value = globalThis[nodeGlobalsKey];
 
               // override lazy getter
               Object.defineProperty(global, nodeGlobalsKey, {
                 configurable: true,
                 enumerable: descriptor.enumerable,
-                value: val,
-                writable:
-                  descriptor.writable === true ||
-                  // Node 19 makes performance non-readable. This is probably not the correct solution.
-                  nodeGlobalsKey === 'performance',
+                value,
+                writable: true,
               });
-              return val;
+
+              return value;
             },
-            set(val: unknown) {
+            set(value: unknown) {
               // override lazy getter
               Object.defineProperty(global, nodeGlobalsKey, {
                 configurable: true,
                 enumerable: descriptor.enumerable,
-                value: val,
+                value,
                 writable: true,
               });
             },