[Lists] Add an instance of ExceptionListClient with server extensio…

…n points turned off to context object provided to callbacks (#123885)

* Add an instance of ExceptionListClient with server extension points turned off to the `context` provided to callbacks
* Unit test cases to validate context

x-pack/plugins/lists/server/services/exception_lists/exception_list_client.test.ts

@@ -12,6 +12,7 @@ import {
   createExtensionPointStorageMock,
 } from '../extension_points/extension_point_storage.mock';
 import type { ExtensionPointCallbackDataArgument } from '../extension_points';
+import { httpServerMock } from '../../../../../../src/core/server/mocks';
 
 import {
   getCreateExceptionListItemOptionsMock,
@@ -49,13 +50,16 @@ describe('exception_list_client', () => {
   describe('server extension points execution', () => {
     let extensionPointStorageContext: ExtensionPointStorageContextMock;
     let exceptionListClient: ExceptionListClient;
+    let kibanaRequest: ReturnType<typeof httpServerMock.createKibanaRequest>;
 
     beforeEach(() => {
       extensionPointStorageContext = createExtensionPointStorageMock();
+      kibanaRequest = httpServerMock.createKibanaRequest();
     });
 
     it('should initialize class instance with `enableServerExtensionPoints` enabled by default', async () => {
       exceptionListClient = new ExceptionListClient({
+        request: kibanaRequest,
         savedObjectsClient: getExceptionListSavedObjectClientMock(),
         serverExtensionsClient: extensionPointStorageContext.extensionPointStorage.getClient(),
         user: 'elastic',
@@ -98,6 +102,7 @@ describe('exception_list_client', () => {
         describe('and server extension points are enabled', () => {
           beforeEach(() => {
             exceptionListClient = new ExceptionListClient({
+              request: kibanaRequest,
               savedObjectsClient: getExceptionListSavedObjectClientMock(),
               serverExtensionsClient:
                 extensionPointStorageContext.extensionPointStorage.getClient(),
@@ -111,6 +116,15 @@ describe('exception_list_client', () => {
             expect(getExtensionPointCallback()).toHaveBeenCalled();
           });
 
+          it('should provide `context` object to extension point callbacks', async () => {
+            await callExceptionListClientMethod();
+
+            expect(getExtensionPointCallback().mock.calls[0][0].context).toEqual({
+              exceptionListClient: expect.any(ExceptionListClient),
+              request: kibanaRequest,
+            });
+          });
+
           it('should error if extension point callback throws an error', async () => {
             const error = new Error('foo');
             const extensionCallback = getExtensionPointCallback();
@@ -157,6 +171,7 @@ describe('exception_list_client', () => {
           beforeEach(() => {
             exceptionListClient = new ExceptionListClient({
               enableServerExtensionPoints: false,
+              request: kibanaRequest,
               savedObjectsClient: getExceptionListSavedObjectClientMock(),
               serverExtensionsClient:
                 extensionPointStorageContext.extensionPointStorage.getClient(),
@@ -305,6 +320,7 @@ describe('exception_list_client', () => {
       (methodName, callExceptionListClientMethod, getExtensionPointCallback) => {
         beforeEach(() => {
           exceptionListClient = new ExceptionListClient({
+            request: kibanaRequest,
             savedObjectsClient: getExceptionListSavedObjectClientMock(),
             serverExtensionsClient: extensionPointStorageContext.extensionPointStorage.getClient(),
             user: 'elastic',
@@ -317,6 +333,15 @@ describe('exception_list_client', () => {
           expect(getExtensionPointCallback()).toHaveBeenCalled();
         });
 
+        it('should provide `context` object to extension point callbacks', async () => {
+          await callExceptionListClientMethod();
+
+          expect(getExtensionPointCallback().mock.calls[0][0].context).toEqual({
+            exceptionListClient: expect.any(ExceptionListClient),
+            request: kibanaRequest,
+          });
+        });
+
         it('should error if extension point callback throws an error', async () => {
           const error = new Error('foo');
           const extensionCallback = getExtensionPointCallback();
@@ -332,6 +357,7 @@ describe('exception_list_client', () => {
           beforeEach(() => {
             exceptionListClient = new ExceptionListClient({
               enableServerExtensionPoints: false,
+              request: kibanaRequest,
               savedObjectsClient: getExceptionListSavedObjectClientMock(),
               serverExtensionsClient:
                 extensionPointStorageContext.extensionPointStorage.getClient(),

x-pack/plugins/lists/server/services/exception_lists/exception_list_client.ts

@@ -103,7 +103,24 @@ export class ExceptionListClient {
   }
 
   private getServerExtensionCallbackContext(): ServerExtensionCallbackContext {
+    const { user, serverExtensionsClient, savedObjectsClient, request } = this;
+    let exceptionListClient: undefined | ExceptionListClient;
+
     return {
+      // Lazy getter so that we only initialize a new instance of the class if needed
+      get exceptionListClient(): ExceptionListClient {
+        if (!exceptionListClient) {
+          exceptionListClient = new ExceptionListClient({
+            enableServerExtensionPoints: false,
+            request,
+            savedObjectsClient,
+            serverExtensionsClient,
+            user,
+          });
+        }
+
+        return exceptionListClient;
+      },
       request: this.request,
     };
   }

x-pack/plugins/lists/server/services/extension_points/extension_point_storage.mock.ts

@@ -8,6 +8,7 @@
 import { MockedLogger, loggerMock } from '@kbn/logging/mocks';
 
 import { httpServerMock } from '../../../../../../src/core/server/mocks';
+import { ExceptionListClient } from '../exception_lists/exception_list_client';
 
 import { ExtensionPointStorage } from './extension_point_storage';
 import {
@@ -122,6 +123,7 @@ export const createExtensionPointStorageMock = (
 
   return {
     callbackContext: {
+      exceptionListClient: {} as unknown as ExceptionListClient,
       request: httpServerMock.createKibanaRequest(),
     },
     exceptionPreCreate,

x-pack/plugins/lists/server/services/extension_points/extension_point_storage_client.test.ts

@@ -138,9 +138,7 @@ describe('When using the ExtensionPointStorageClient', () => {
         if (extensionPointsMock.type === 'exceptionsListPreCreateItem') {
           expect(extensionPointsMock.callback).toHaveBeenCalledWith(
             expect.objectContaining({
-              context: {
-                request: expect.any(Object),
-              },
+              context: callbackContext,
             })
           );
         }

x-pack/plugins/lists/server/services/extension_points/types.ts

@@ -19,6 +19,7 @@ import {
   UpdateExceptionListItemOptions,
 } from '../exception_lists/exception_list_client_types';
 import { PromiseFromStreams } from '../exception_lists/import_exception_list_and_items';
+import type { ExceptionListClient } from '../exception_lists/exception_list_client';
 
 /**
  * The `this` context provided to extension point's callback function
@@ -30,6 +31,13 @@ export interface ServerExtensionCallbackContext {
    * is not triggered via one of the HTTP handlers
    */
   request?: KibanaRequest;
+
+  /**
+   * An `ExceptionListClient` instance that **DOES NOT** execute server extension point callbacks.
+   * This client should be used when needing to access Exception List content from within an Extension
+   * Point to avoid circular infinite loops
+   */
+  exceptionListClient: ExceptionListClient;
 }
 
 export type ServerExtensionCallback<A extends object | void = void, R = A> = (args: {