feat: add detail field to PaginatedResult and extend ErrorInfo tests

- We also need the detail returned from errorDetail field in the paginated response, since this can also come over REST.

Author: splindsay-92

ably.d.ts

@@ -3384,6 +3384,10 @@ export declare interface HttpPaginatedResponse<T = any> extends PaginatedResult<
    * The error message if the `X-Ably-Errormessage` HTTP header is sent in the response.
    */
   errorMessage: string;
+  /**
+   * Optional map of string key-value pairs containing structured error metadata, extracted from the response body when present.
+   */
+  errorDetail?: Record<string, string>;
   /**
    * The headers of the response.
    */
@@ -3706,6 +3710,7 @@ export declare class ErrorInfo extends Error {
    * @param code - Ably [error code](https://github.com/ably/ably-common/blob/main/protocol/errors.json).
    * @param statusCode - HTTP Status Code corresponding to this error.
    * @param cause - The underlying cause of the error.
+   * @param detail - Optional map of string key-value pairs containing structured metadata associated with the error.
    */
-  constructor(message: string, code: number, statusCode: number, cause?: ErrorInfo);
+  constructor(message: string, code: number, statusCode: number, cause?: ErrorInfo, detail?: Record<string, string>);
 }

src/common/lib/client/paginatedresource.ts

@@ -197,6 +197,7 @@ export class HttpPaginatedResponse<T> extends PaginatedResult<T> {
   headers: ResponseHeaders;
   errorCode?: number | null;
   errorMessage?: string | null;
+  errorDetail?: Record<string, string>;
 
   constructor(
     resource: PaginatedResource,
@@ -212,6 +213,7 @@ export class HttpPaginatedResponse<T> extends PaginatedResult<T> {
     this.headers = headers;
     this.errorCode = err && err.code;
     this.errorMessage = err && err.message;
+    this.errorDetail = err?.detail;
   }
 
   toJSON() {
@@ -222,6 +224,7 @@ export class HttpPaginatedResponse<T> extends PaginatedResult<T> {
       headers: this.headers,
       errorCode: this.errorCode,
       errorMessage: this.errorMessage,
+      errorDetail: this.errorDetail,
     };
   }
 }

src/common/lib/types/errorinfo.ts

@@ -41,14 +41,15 @@ export default class ErrorInfo extends Error implements IPartialErrorInfo, API.E
   href?: string;
   detail?: Record<string, string>;
 
-  constructor(message: string, code: number, statusCode: number, cause?: ErrorInfo) {
+  constructor(message: string, code: number, statusCode: number, cause?: ErrorInfo, detail?: Record<string, string>) {
     super(message);
     if (typeof Object.setPrototypeOf !== 'undefined') {
       Object.setPrototypeOf(this, ErrorInfo.prototype);
     }
     this.code = code;
     this.statusCode = statusCode;
     this.cause = cause;
+    this.detail = detail;
   }
 
   toString(): string {

test/unit/errorinfo.test.js

@@ -61,6 +61,33 @@ define(['chai', 'ably'], function (chai, Ably) {
 
         expect(str).to.not.contain('detail=');
       });
+
+      it('should accept detail as a constructor parameter', function () {
+        const detail = { reason: 'content policy violation', category: 'moderation' };
+        const errorInfo = new ErrorInfo('Rejected', 42211, 400, undefined, detail);
+
+        expect(errorInfo).to.be.instanceOf(ErrorInfo);
+        expect(errorInfo.message).to.equal('Rejected');
+        expect(errorInfo.code).to.equal(42211);
+        expect(errorInfo.statusCode).to.equal(400);
+        expect(errorInfo.cause).to.be.undefined;
+        expect(errorInfo.detail).to.deep.equal({ reason: 'content policy violation', category: 'moderation' });
+      });
+
+      it('should accept both cause and detail as constructor parameters', function () {
+        const cause = new ErrorInfo('Root cause', 50000, 500);
+        const detail = { reason: 'spam' };
+        const errorInfo = new ErrorInfo('Rejected', 42211, 400, cause, detail);
+
+        expect(errorInfo.cause).to.equal(cause);
+        expect(errorInfo.detail).to.deep.equal({ reason: 'spam' });
+      });
+
+      it('should leave detail undefined when not passed to constructor', function () {
+        const errorInfo = new ErrorInfo('Some error', 50000, 500);
+
+        expect(errorInfo.detail).to.be.undefined;
+      });
     });
   });
 });