fix: support node20

Author: OrKoN

.github/workflows/run-tests.yml

@@ -20,6 +20,7 @@ jobs:
           - windows-latest
           - macos-latest
         node:
+          - 20
           - 22
           - 24
     steps:
@@ -32,16 +33,30 @@ jobs:
         uses: actions/setup-node@a0853c24544627f65ddf259abe73b1d18a591444 # v5.0.0
         with:
           cache: npm
-          node-version: ${{ matrix.node }}
+          node-version: 22
 
       - name: Install dependencies
         run: npm ci
 
+      - name: Build
+        run: npm run build
+
+      - name: Set up Node.js
+        uses: actions/setup-node@a0853c24544627f65ddf259abe73b1d18a591444 # v5.0.0
+        with:
+          cache: npm
+          node-version: ${{ matrix.node }}
+
       - name: Disable AppArmor
         if: ${{ matrix.os == 'ubuntu-latest' }}
         run: echo 0 | sudo tee /proc/sys/kernel/apparmor_restrict_unprivileged_userns
 
+      - name: Run tests (node20)
+        if: ${{ matrix.node == '20' }}
+        run: npm run test:node20
+
       - name: Run tests
+        if: ${{ matrix.node != '20' }}
         run: npm run test
 
   # Gating job for branch protection.

README.md

@@ -26,7 +26,7 @@ MCP clients.
 
 ## Requirements
 
-- [Node.js 22](https://nodejs.org/) or newer.
+- [Node.js 20](https://nodejs.org/) or newer.
 - [Chrome](https://www.google.com/chrome/) current stable version or newer.
 - [npm](https://www.npmjs.com/).
 

package-lock.json

@@ -16,6 +16,7 @@
     "docs:generate": "node --experimental-strip-types scripts/generate-docs.ts",
     "start": "npm run build && node build/src/index.js",
     "start-debug": "DEBUG=mcp:* DEBUG_COLORS=false npm run build && node build/src/index.js",
+    "test:node20": "node --require ./build/tests/setup.js --test-reporter spec --test-force-exit --test 'build/tests'",
     "test": "npm run build && node --require ./build/tests/setup.js --test-reporter spec --test-force-exit --test 'build/tests/**/*.test.js'",
     "test:only": "npm run build && node --require ./build/tests/setup.js --test-reporter spec --test-force-exit --test --test-only 'build/tests/**/*.test.js'",
     "test:only:no-build": "node --require ./build/tests/setup.js --test-reporter spec --test-force-exit --test --test-only 'build/tests/**/*.test.js'",
@@ -50,7 +51,7 @@
     "@types/yargs": "^17.0.33",
     "@typescript-eslint/eslint-plugin": "^8.43.0",
     "@typescript-eslint/parser": "^8.43.0",
-    "chrome-devtools-frontend": "1.0.1515796",
+    "chrome-devtools-frontend": "1.0.1516909",
     "eslint": "^9.35.0",
     "globals": "^16.4.0",
     "prettier": "^3.6.2",

package.json

@@ -5,6 +5,8 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
+import './polyfill.js';
+
 import {McpServer} from '@modelcontextprotocol/sdk/server/mcp.js';
 import {StdioServerTransport} from '@modelcontextprotocol/sdk/server/stdio.js';
 import {

src/index.ts

@@ -0,0 +1,19 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+// For Node 20.
+if (!Promise.withResolvers) {
+  Promise.withResolvers = function <T>() {
+    let resolve, reject;
+    const promise = new Promise<T>((_resolve, _reject) => {
+      resolve = _resolve;
+      reject = _reject;
+    });
+    return {promise, resolve, reject} as unknown as ReturnType<
+      typeof Promise.withResolvers<T>
+    >;
+  };
+}

src/polyfill.ts

@@ -5,6 +5,13 @@
  */
 import {it} from 'node:test';
 
+if (!it.snapshot) {
+  it.snapshot = {
+    setResolveSnapshotPath: () => {},
+    setDefaultSnapshotSerializers: () => {},
+  };
+}
+
 // This is run by Node when we execute the tests via the --require flag.
 it.snapshot.setResolveSnapshotPath(testPath => {
   // By default the snapshots go into the build directory, but we want them

tests/setup.ts

@@ -5,18 +5,18 @@ exports[`performance > performance_analyze_insight > returns the information on
 This insight is used to analyze the time spent that contributed to the final LCP time and identify which of the 4 phases (or 2 if there was no LCP resource) are contributing most to the delay in rendering the LCP element.
 
 ## Detailed analysis:
-The Largest Contentful Paint (LCP) time for this navigation was 129.2 ms.
+The Largest Contentful Paint (LCP) time for this navigation was 129 ms.
 The LCP element is an image fetched from \`https://web-dev.imgix.net/image/kheDArv5csY6rvQUJDbWRscckLr1/4i7JstVZvgTFk9dxCe4a.svg\`.
 ## LCP resource network request: https://web-dev.imgix.net/image/kheDArv5csY6rvQUJDbWRscckLr1/4i7JstVZvgTFk9dxCe4a.svg
 Timings:
-- Queued at: 41.1 ms
-- Request sent at: 46.6 ms
-- Download complete at: 55.8 ms
-- Main thread processing completed at: 58.2 ms
+- Queued at: 41 ms
+- Request sent at: 47 ms
+- Download complete at: 56 ms
+- Main thread processing completed at: 58 ms
 Durations:
 - Download time: 0.3 ms
-- Main thread processing time: 2.3 ms
-- Total duration: 17.1 ms
+- Main thread processing time: 2 ms
+- Total duration: 17 ms
 Redirects: no redirects
 Status code: 200
 MIME Type: image/svg+xml
@@ -29,10 +29,10 @@ Initiators (root request to the request that directly loaded this one): none
 
 We can break this time down into the 4 phases that combine to make the LCP time:
 
-- Time to first byte: 7.9 ms (6.1% of total LCP time)
-- Resource load delay: 33.2 ms (25.7% of total LCP time)
-- Resource load duration: 14.7 ms (11.4% of total LCP time)
-- Element render delay: 73.4 ms (56.8% of total LCP time)
+- Time to first byte: 8 ms (6.1% of total LCP time)
+- Resource load delay: 33 ms (25.7% of total LCP time)
+- Resource load duration: 15 ms (11.4% of total LCP time)
+- Element render delay: 73 ms (56.8% of total LCP time)
 
 ## Estimated savings: none
 

tests/tools/performance.test.js.snapshot

@@ -161,7 +161,7 @@ describe('performance', () => {
           context,
         );
 
-        t.assert.snapshot(response.responseLines.join('\n'));
+        t.assert.snapshot?.(response.responseLines.join('\n'));
       });
     });
 

tests/tools/performance.test.ts

@@ -6,10 +6,10 @@ Network throttling: none
 Metrics (lab / observed):
   - LCP: 129 ms, event: (eventKey: r-6063, ts: 122411126100)
   - LCP breakdown:
-    - TTFB: 7.9 ms, bounds: {min: 122410996889, max: 122411004828}
-    - Load delay: 33.2 ms, bounds: {min: 122411004828, max: 122411037986}
-    - Load duration: 14.7 ms, bounds: {min: 122411037986, max: 122411052690}
-    - Render delay: 73.4 ms, bounds: {min: 122411052690, max: 122411126100}
+    - TTFB: 8 ms, bounds: {min: 122410996889, max: 122411004828}
+    - Load delay: 33 ms, bounds: {min: 122411004828, max: 122411037986}
+    - Load duration: 15 ms, bounds: {min: 122411037986, max: 122411052690}
+    - Render delay: 73 ms, bounds: {min: 122411052690, max: 122411126100}
   - CLS: 0.00
 Metrics (field / real users): n/a – no data for this page in CrUX
 Available insights: