fix(fetch): preserve node error fields across serialization

packages/playwright-core/src/client/errors.ts

@@ -15,7 +15,7 @@
  */
 
 import { isError } from '@isomorphic/rtti';
-import { parseSerializedValue, serializeValue } from '@protocol/serializers';
+import { parseSerializedValue, parseSystemErrorFields, serializeSystemErrorFields, serializeValue, systemErrorMessage } from '@protocol/serializers';
 
 import type { SerializedError } from './channels';
 
@@ -51,7 +51,7 @@ export function isTargetClosedError(error: Error) {
 
 export function serializeError(e: any): SerializedError {
   if (isError(e))
-    return { error: { message: e.message, stack: e.stack, name: e.name } };
+    return { error: { message: systemErrorMessage(e), stack: e.stack, name: e.name, ...serializeSystemErrorFields(e) } };
   return { value: serializeValue(e, value => ({ fallThrough: value })) };
 }
 
@@ -71,5 +71,6 @@ export function parseError(error: SerializedError): PlaywrightError {
   else
     e = Object.assign(new PlaywrightError(error.error.message), { name: error.error.name });
   e.stack = error.error.stack || '';
+  parseSystemErrorFields(error.error, e);
   return e;
 }

packages/playwright-core/src/server/errors.ts

@@ -15,7 +15,7 @@
  */
 
 import { isError } from '@isomorphic/rtti';
-import { parseSerializedValue, serializeValue } from '@protocol/serializers';
+import { parseSerializedValue, parseSystemErrorFields, serializeSystemErrorFields, serializeValue, systemErrorMessage } from '@protocol/serializers';
 
 import type { SerializedError } from './channels';
 
@@ -50,7 +50,7 @@ export function isTargetClosedError(error: Error) {
 
 export function serializeError(e: any): SerializedError {
   if (isError(e))
-    return { error: { message: e.message, stack: e.stack, name: e.name } };
+    return { error: { message: systemErrorMessage(e), stack: e.stack, name: e.name, ...serializeSystemErrorFields(e) } };
   return { value: serializeValue(e, value => ({ fallThrough: value })) };
 }
 
@@ -63,5 +63,6 @@ export function parseError(error: SerializedError): Error {
   const e = new Error(error.error.message);
   e.stack = error.error.stack || '';
   e.name = error.error.name;
+  parseSystemErrorFields(error.error, e);
   return e;
 }

packages/protocol/spec/serialized.yml

@@ -104,4 +104,11 @@ SerializedError:
         message: string
         name: string
         stack: string?
+        # See https://nodejs.org/api/errors.html#class-systemerror
+        code: string?
+        errno: int?
+        syscall: string?
+        address: string?
+        port: int?
+        hostname: string?
     value: SerializedValue?

packages/protocol/src/serializers.ts

@@ -14,7 +14,42 @@
  * limitations under the License.
  */
 
-import type { SerializedValue } from '@protocol/structs';
+import type { SerializedError, SerializedValue } from '@protocol/structs';
+
+type SerializedSystemError = NonNullable<SerializedError['error']>;
+
+// Structured fields of a Node.js system error, see https://nodejs.org/api/errors.html#class-systemerror.
+const systemErrorFields: { [key in keyof SerializedSystemError]?: 'string' | 'number' } = {
+  code: 'string',
+  errno: 'number',
+  syscall: 'string',
+  address: 'string',
+  port: 'number',
+  hostname: 'string',
+};
+
+export function serializeSystemErrorFields(error: any): Partial<SerializedSystemError> {
+  const result: any = {};
+  for (const [field, type] of Object.entries(systemErrorFields)) {
+    if (typeof error[field] === type)
+      result[field] = error[field];
+  }
+  return result;
+}
+
+export function parseSystemErrorFields(error: SerializedSystemError, target: Error) {
+  for (const [field, type] of Object.entries(systemErrorFields)) {
+    if (typeof (error as any)[field] === type)
+      (target as any)[field] = (error as any)[field];
+  }
+}
+
+export function systemErrorMessage(error: any): string {
+  const message = error.message;
+  if (typeof error.code !== 'string' || !/^E[A-Z0-9]+$/.test(error.code) || message.includes(error.code))
+    return message;
+  return `${message} (${error.code})`;
+}
 
 export function parseSerializedValue(value: SerializedValue, handles: any[] | undefined): any {
   return innerParseSerializedValue(value, handles, new Map(), []);

packages/protocol/src/structs.d.ts

@@ -314,6 +314,12 @@ export type SerializedError = {
     message: string,
     name: string,
     stack?: string,
+    code?: string,
+    errno?: number,
+    syscall?: string,
+    address?: string,
+    port?: number,
+    hostname?: string,
   },
   value?: SerializedValue,
 };

packages/protocol/src/validator.ts

@@ -2998,6 +2998,12 @@ scheme.SerializedError = tObject({
     message: tString,
     name: tString,
     stack: tOptional(tString),
+    code: tOptional(tString),
+    errno: tOptional(tInt),
+    syscall: tOptional(tString),
+    address: tOptional(tString),
+    port: tOptional(tInt),
+    hostname: tOptional(tString),
   })),
   value: tOptional(tType('SerializedValue')),
 });

tests/library/global-fetch.spec.ts

@@ -719,6 +719,32 @@ it('should retry ECONNRESET', {
   await request.dispose();
 });
 
+it('should expose node error fields on network errors', {
+  annotation: { type: 'issue', description: 'https://github.com/microsoft/playwright/issues/42532' }
+}, async ({ playwright, server }) => {
+  // Reset the connection so that node reports a system error instead of a plain 'socket hang up'.
+  server.setRoute('/reset', req => req.socket.resetAndDestroy());
+  const request = await playwright.request.newContext();
+  const error = await request.get(server.PREFIX + '/reset', { maxRetries: 0 }).catch(e => e);
+  expect(error.message).toContain('ECONNRESET');
+  expect(error.code).toBe('ECONNRESET');
+  expect(error.syscall).toBe('read');
+  expect(typeof error.errno).toBe('number');
+  await request.dispose();
+});
+
+it('should append node error code to the message', {
+  annotation: { type: 'issue', description: 'https://github.com/microsoft/playwright/issues/42532' }
+}, async ({ playwright, server }) => {
+  // Node reports this one as a plain 'socket hang up' that does not mention the code.
+  server.setRoute('/hangup', req => req.socket.destroy());
+  const request = await playwright.request.newContext();
+  const error = await request.get(server.PREFIX + '/hangup', { maxRetries: 0 }).catch(e => e);
+  expect(error.message).toContain('socket hang up (ECONNRESET)');
+  expect(error.code).toBe('ECONNRESET');
+  await request.dispose();
+});
+
 it('should not crash when server refuses body before reading it', {
   annotation: { type: 'issue', description: 'https://github.com/microsoft/playwright/issues/42074' }
 }, async ({ playwright, server }) => {