1 files changed, 44 insertions, 0 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
new file mode 100644
index 0000000000..ee006cdeb3
--- /dev/null
+++ b/dom/webgpu/tests/cts/checkout/src/common/internal/logging/log_message.ts
@@ -0,0 +1,44 @@
+import { ErrorWithExtra } from '../../util/util.js';
+import { extractImportantStackTrace } from '../stack.js';
+
+export class LogMessageWithStack extends Error {
+  readonly extra: unknown;
+
+  private stackHiddenMessage: string | undefined = undefined;
+
+  constructor(name: string, ex: Error | ErrorWithExtra) {
+    super(ex.message);
+
+    this.name = name;
+    this.stack = ex.stack;
+    if ('extra' in ex) {
+      this.extra = ex.extra;
+    }
+  }
+
+  /** Set a flag so the stack is not printed in toJSON(). */
+  setStackHidden(stackHiddenMessage: string) {
+    this.stackHiddenMessage ??= stackHiddenMessage;
+  }
+
+  toJSON(): string {
+    let m = this.name;
+    if (this.message) m += ': ' + this.message;
+    if (this.stack) {
+      if (this.stackHiddenMessage === undefined) {
+        m += '\n' + extractImportantStackTrace(this);
+      } else if (this.stackHiddenMessage) {
+        m += `\n  at (elided: ${this.stackHiddenMessage})`;
+      }
+    }
+    return m;
+  }
+}
+
+/**
+ * Returns a string, nicely indented, for debug logs.
+ * This is used in the cmdline and wpt runtimes. In WPT, it shows up in the `*-actual.txt` file.
+ */
+export function prettyPrintLog(log: LogMessageWithStack): string {
+  return '  - ' + log.toJSON().replace(/\n/g, '\n    ');
+}