feat(Default Data Loader Node): Add default text splitter (#15786)

Co-authored-by: cubic-dev-ai[bot] <191113872+cubic-dev-ai[bot]@users.noreply.github.com>

packages/@n8n/nodes-langchain/nodes/document_loaders/DocumentDefaultDataLoader/test/DocumentDefaultDataLoader.node.test.ts

@@ -0,0 +1,72 @@
+import { RecursiveCharacterTextSplitter } from '@langchain/textsplitters';
+import type { ISupplyDataFunctions } from 'n8n-workflow';
+import { NodeConnectionTypes } from 'n8n-workflow';
+
+import { DocumentDefaultDataLoader } from '../DocumentDefaultDataLoader.node';
+
+jest.mock('@langchain/textsplitters', () => ({
+	RecursiveCharacterTextSplitter: jest.fn().mockImplementation(() => ({
+		splitDocuments: jest.fn(
+			async (docs: Array<Record<string, unknown>>): Promise<Array<Record<string, unknown>>> =>
+				docs.map((doc) => ({ ...doc, split: true })),
+		),
+	})),
+}));
+
+describe('DocumentDefaultDataLoader', () => {
+	let loader: DocumentDefaultDataLoader;
+
+	beforeEach(() => {
+		loader = new DocumentDefaultDataLoader();
+		jest.clearAllMocks();
+	});
+
+	it('should supply data with recursive char text splitter', async () => {
+		const context = {
+			getNode: jest.fn(() => ({ typeVersion: 1.1 })),
+			getNodeParameter: jest.fn().mockImplementation((paramName, _itemIndex) => {
+				switch (paramName) {
+					case 'dataType':
+						return 'json';
+					case 'textSplittingMode':
+						return 'simple';
+					case 'binaryDataKey':
+						return 'data';
+					default:
+						return;
+				}
+			}),
+		} as unknown as ISupplyDataFunctions;
+
+		await loader.supplyData.call(context, 0);
+		expect(RecursiveCharacterTextSplitter).toHaveBeenCalledWith({
+			chunkSize: 1000,
+			chunkOverlap: 200,
+		});
+	});
+
+	it('should supply data with custom text splitter', async () => {
+		const customSplitter = { splitDocuments: jest.fn(async (docs) => docs) };
+		const context = {
+			getNode: jest.fn(() => ({ typeVersion: 1.1 })),
+			getNodeParameter: jest.fn().mockImplementation((paramName, _itemIndex) => {
+				switch (paramName) {
+					case 'dataType':
+						return 'json';
+					case 'textSplittingMode':
+						return 'custom';
+					case 'binaryDataKey':
+						return 'data';
+					default:
+						return;
+				}
+			}),
+			getInputConnectionData: jest.fn(async () => customSplitter),
+		} as unknown as ISupplyDataFunctions;
+		await loader.supplyData.call(context, 0);
+		expect(context.getInputConnectionData).toHaveBeenCalledWith(
+			NodeConnectionTypes.AiTextSplitter,
+			0,
+		);
+	});
+});