perf(core): Batch items sent in runonceforeachitem mode (no-changelog) (#11870)

Co-authored-by: Iván Ovejero <ivov.src@gmail.com>

packages/nodes-base/nodes/Code/test/JsTaskRunnerSandbox.test.ts

@@ -0,0 +1,61 @@
+import { mock } from 'jest-mock-extended';
+import type { IExecuteFunctions } from 'n8n-workflow';
+import { createResultOk } from 'n8n-workflow';
+
+import { JsTaskRunnerSandbox } from '../JsTaskRunnerSandbox';
+
+describe('JsTaskRunnerSandbox', () => {
+	describe('runCodeForEachItem', () => {
+		it('should chunk the input items and execute the code for each chunk', async () => {
+			const jsCode = 'console.log($item);';
+			const nodeMode = 'runOnceForEachItem';
+			const workflowMode = 'manual';
+			const executeFunctions = mock<IExecuteFunctions>();
+			const sandbox = new JsTaskRunnerSandbox(jsCode, nodeMode, workflowMode, executeFunctions, 2);
+			let i = 1;
+			executeFunctions.startJob.mockResolvedValue(createResultOk([{ json: { item: i++ } }]));
+
+			const numInputItems = 5;
+			await sandbox.runCodeForEachItem(numInputItems);
+
+			// eslint-disable-next-line @typescript-eslint/unbound-method
+			expect(executeFunctions.startJob).toHaveBeenCalledTimes(3);
+			const calls = executeFunctions.startJob.mock.calls;
+			expect(calls).toEqual([
+				[
+					'javascript',
+					{
+						code: jsCode,
+						nodeMode,
+						workflowMode,
+						continueOnFail: executeFunctions.continueOnFail(),
+						chunk: { startIndex: 0, count: 2 },
+					},
+					0,
+				],
+				[
+					'javascript',
+					{
+						code: jsCode,
+						nodeMode,
+						workflowMode,
+						continueOnFail: executeFunctions.continueOnFail(),
+						chunk: { startIndex: 2, count: 2 },
+					},
+					0,
+				],
+				[
+					'javascript',
+					{
+						code: jsCode,
+						nodeMode,
+						workflowMode,
+						continueOnFail: executeFunctions.continueOnFail(),
+						chunk: { startIndex: 4, count: 1 },
+					},
+					0,
+				],
+			]);
+		});
+	});
+});