From 995560fad01c7b57d78af7833f165a8fd5238a57 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Simon=20Z=C3=BCnd?= <szuend@chromium.org>
Date: Fri, 6 Feb 2026 08:14:35 +0100
Subject: [PATCH] chore: implement formatting of Error console.log arguments

---
 src/DevtoolsUtils.ts                          |  8 ++++
 src/formatters/ConsoleFormatter.ts            | 12 +++++-
 .../ConsoleFormatter.test.js.snapshot         | 10 +++++
 tests/formatters/ConsoleFormatter.test.ts     | 39 +++++++++++++++++++
 4 files changed, 68 insertions(+), 1 deletion(-)

diff --git a/src/DevtoolsUtils.ts b/src/DevtoolsUtils.ts
index d6058169d..38a66bce4 100644
--- a/src/DevtoolsUtils.ts
+++ b/src/DevtoolsUtils.ts
@@ -292,6 +292,14 @@ export class SymbolizedError {
     }
     return details.text;
   }
+
+  static createForTesting(
+    message: string,
+    stackTrace?: DevTools.StackTrace.StackTrace.StackTrace,
+    cause?: SymbolizedError,
+  ) {
+    return new SymbolizedError(message, stackTrace, cause);
+  }
 }
 
 export async function createStackTraceForConsoleMessage(
diff --git a/src/formatters/ConsoleFormatter.ts b/src/formatters/ConsoleFormatter.ts
index 40e265f4d..71968393e 100644
--- a/src/formatters/ConsoleFormatter.ts
+++ b/src/formatters/ConsoleFormatter.ts
@@ -136,6 +136,14 @@ export class ConsoleFormatter {
   }
 
   #formatArg(arg: unknown) {
+    if (arg instanceof SymbolizedError) {
+      return [
+        arg.message,
+        this.#formatStackTrace(arg.stackTrace, /* includeHeading */ false),
+      ]
+        .filter(line => !!line)
+        .join('\n');
+    }
     return typeof arg === 'object' ? JSON.stringify(arg) : String(arg);
   }
 
@@ -157,13 +165,15 @@ export class ConsoleFormatter {
 
   #formatStackTrace(
     stackTrace: DevTools.DevTools.StackTrace.StackTrace.StackTrace | undefined,
+    includeHeading = true,
   ): string {
     if (!stackTrace) {
       return '';
     }
 
+    const heading = includeHeading ? ['### Stack trace'] : [];
     return [
-      '### Stack trace',
+      ...heading,
       this.#formatFragment(stackTrace.syncFragment),
       ...stackTrace.asyncFragments.map(this.#formatAsyncFragment.bind(this)),
       'Note: line and column numbers use 1-based indexing',
diff --git a/tests/formatters/ConsoleFormatter.test.js.snapshot b/tests/formatters/ConsoleFormatter.test.js.snapshot
index 67a6e59e9..87c16e94b 100644
--- a/tests/formatters/ConsoleFormatter.test.js.snapshot
+++ b/tests/formatters/ConsoleFormatter.test.js.snapshot
@@ -25,6 +25,16 @@ at schedule (util.ts:5:2)
 Note: line and column numbers use 1-based indexing
 `;
 
+exports[`ConsoleFormatter > toStringDetailed > formats a console message with an Error object argument 1`] = `
+ID: 8
+Message: log> JSHandle@error
+### Arguments
+Arg #0: TypeError: Cannot read properties of undefined
+at foo (foo.ts:10:2)
+at bar (foo.ts:20:2)
+Note: line and column numbers use 1-based indexing
+`;
+
 exports[`ConsoleFormatter > toStringDetailed > formats a console.error message 1`] = `
 ID: 4
 Message: error> Something went wrong
diff --git a/tests/formatters/ConsoleFormatter.test.ts b/tests/formatters/ConsoleFormatter.test.ts
index 58e727f3f..efc1a3b72 100644
--- a/tests/formatters/ConsoleFormatter.test.ts
+++ b/tests/formatters/ConsoleFormatter.test.ts
@@ -7,6 +7,7 @@
 import assert from 'node:assert';
 import {describe, it} from 'node:test';
 
+import {SymbolizedError} from '../../src/DevtoolsUtils.js';
 import {ConsoleFormatter} from '../../src/formatters/ConsoleFormatter.js';
 import {UncaughtError} from '../../src/PageCollector.js';
 import type {ConsoleMessage} from '../../src/third_party/index.js';
@@ -260,6 +261,44 @@ describe('ConsoleFormatter', () => {
       ).toStringDetailed();
       t.assert.snapshot?.(result);
     });
+
+    it('formats a console message with an Error object argument', async t => {
+      const message = createMockMessage({
+        type: () => 'log',
+        text: () => 'JSHandle@error',
+      });
+      const stackTrace = {
+        syncFragment: {
+          frames: [
+            {
+              line: 10,
+              column: 2,
+              url: 'foo.ts',
+              name: 'foo',
+            },
+            {
+              line: 20,
+              column: 2,
+              url: 'foo.ts',
+              name: 'bar',
+            },
+          ],
+        },
+        asyncFragments: [],
+      } as unknown as DevTools.StackTrace.StackTrace.StackTrace;
+      const error = SymbolizedError.createForTesting(
+        'TypeError: Cannot read properties of undefined',
+        stackTrace,
+      );
+
+      const result = (
+        await ConsoleFormatter.from(message, {
+          id: 8,
+          resolvedArgsForTesting: [error],
+        })
+      ).toStringDetailed();
+      t.assert.snapshot?.(result);
+    });
   });
   describe('toJSON', () => {
     it('formats a console.log message', async () => {