1 files changed, 44 insertions, 7 deletions
diff --git a/dom/webgpu/tests/cts/checkout/src/common/internal/logging/log_message.ts b/dom/webgpu/tests/cts/checkout/src/common/internal/logging/log_message.ts
index ee006cdeb3..b01c08b56e 100644
--- a/dom/webgpu/tests/cts/checkout/src/common/internal/logging/log_message.ts
+++ b/dom/webgpu/tests/cts/checkout/src/common/internal/logging/log_message.ts
@@ -1,19 +1,36 @@
 import { ErrorWithExtra } from '../../util/util.js';
 import { extractImportantStackTrace } from '../stack.js';
 
+import { LogMessageRawData } from './result.js';
+
 export class LogMessageWithStack extends Error {
   readonly extra: unknown;
 
   private stackHiddenMessage: string | undefined = undefined;
 
-  constructor(name: string, ex: Error | ErrorWithExtra) {
-    super(ex.message);
+  /**
+   * Wrap an Error (which was created to capture the stack at that point) into a
+   * LogMessageWithStack (which has extra stuff for good log messages).
+   *
+   * The original `ex.name` is ignored. Inclued it in the `name` parameter if it
+   * needs to be preserved.
+   */
+  static wrapError(name: string, ex: Error | ErrorWithExtra) {
+    return new LogMessageWithStack({
+      name,
+      message: ex.message,
+      stackHiddenMessage: undefined,
+      stack: ex.stack,
+      extra: 'extra' in ex ? ex.extra : undefined,
+    });
+  }
 
-    this.name = name;
-    this.stack = ex.stack;
-    if ('extra' in ex) {
-      this.extra = ex.extra;
-    }
+  constructor(o: LogMessageRawData) {
+    super(o.message);
+    this.name = o.name;
+    this.stackHiddenMessage = o.stackHiddenMessage;
+    this.stack = o.stack;
+    this.extra = o.extra;
   }
 
   /** Set a flag so the stack is not printed in toJSON(). */
@@ -21,6 +38,11 @@ export class LogMessageWithStack extends Error {
     this.stackHiddenMessage ??= stackHiddenMessage;
   }
 
+  /**
+   * Print the message for display.
+   *
+   * Note: This is toJSON instead of toString to make it easy to save logs using JSON.stringify.
+   */
   toJSON(): string {
     let m = this.name;
     if (this.message) m += ': ' + this.message;
@@ -33,6 +55,21 @@ export class LogMessageWithStack extends Error {
     }
     return m;
   }
+
+  /**
+   * Flatten the message for sending over a message channel.
+   *
+   * Note `extra` may get mangled by postMessage.
+   */
+  toRawData(): LogMessageRawData {
+    return {
+      name: this.name,
+      message: this.message,
+      stackHiddenMessage: this.stackHiddenMessage,
+      stack: this.stack,
+      extra: this.extra,
+    };
+  }
 }
 
 /**