test(geschichten): cover DocumentMultiSelect search, chip add/remove

Browser-based component spec mirroring PersonTypeahead.svelte.spec.ts:
renders empty input, surfaces pre-selected chips with formatted date,
emits hidden documentIds inputs for each chip, debounces the search
against /api/documents/search, adds a chip on click, hides already-
selected docs from new dropdown results, and removes a chip on × click.

Closes Felix's review B2 on PR #382.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

frontend/src/lib/components/DocumentMultiSelect.svelte.spec.ts

@@ -0,0 +1,126 @@
+import { afterEach, describe, expect, it, vi } from 'vitest';
+import { cleanup, render } from 'vitest-browser-svelte';
+import { page, userEvent } from 'vitest/browser';
+import DocumentMultiSelect from './DocumentMultiSelect.svelte';
+
+const waitForDebounce = () => new Promise((r) => setTimeout(r, 350));
+
+const docFactory = (id: string, title: string, date = '1880-01-01') => ({
+	id,
+	title,
+	documentDate: date,
+	originalFilename: `${title}.pdf`,
+	status: 'UPLOADED',
+	metadataComplete: false,
+	scriptType: 'UNKNOWN' as const,
+	createdAt: '2024-01-01T00:00:00',
+	updatedAt: '2024-01-01T00:00:00'
+});
+
+function mockSearchResponse(items: ReturnType<typeof docFactory>[]) {
+	vi.stubGlobal(
+		'fetch',
+		vi.fn().mockResolvedValue({
+			ok: true,
+			json: vi.fn().mockResolvedValue({ items: items.map((document) => ({ document })) })
+		})
+	);
+}
+
+afterEach(() => {
+	cleanup();
+	vi.unstubAllGlobals();
+});
+
+describe('DocumentMultiSelect — rendering', () => {
+	it('renders an empty chip-input by default', async () => {
+		render(DocumentMultiSelect);
+		await expect.element(page.getByPlaceholder('Dokument suchen…')).toBeInTheDocument();
+	});
+
+	it('renders pre-selected documents as chips with their date', async () => {
+		render(DocumentMultiSelect, {
+			selectedDocuments: [docFactory('d1', 'Brief vom 1. Mai', '1882-05-01')]
+		});
+		await expect.element(page.getByText(/Brief vom 1\. Mai/)).toBeInTheDocument();
+		await expect.element(page.getByText(/01\.05\.1882/)).toBeInTheDocument();
+	});
+
+	it('emits a hidden documentIds input for each pre-selected document', async () => {
+		render(DocumentMultiSelect, {
+			selectedDocuments: [docFactory('d1', 'A'), docFactory('d2', 'B')]
+		});
+		const inputs = document.querySelectorAll<HTMLInputElement>(
+			'input[type="hidden"][name="documentIds"]'
+		);
+		expect(inputs).toHaveLength(2);
+		expect([inputs[0].value, inputs[1].value].sort()).toEqual(['d1', 'd2']);
+	});
+});
+
+describe('DocumentMultiSelect — search and select', () => {
+	it('queries /api/documents/search after debounce and shows results', async () => {
+		mockSearchResponse([docFactory('d1', 'Brief von Eugenie')]);
+		render(DocumentMultiSelect);
+
+		await userEvent.fill(page.getByPlaceholder('Dokument suchen…'), 'Eug');
+		await waitForDebounce();
+
+		expect(globalThis.fetch).toHaveBeenCalledWith(
+			expect.stringMatching(/^\/api\/documents\/search\?q=Eug/)
+		);
+		await expect.element(page.getByText(/Brief von Eugenie/)).toBeInTheDocument();
+	});
+
+	it('adds a chip when a search result is clicked', async () => {
+		mockSearchResponse([docFactory('d1', 'Brief von Eugenie')]);
+		render(DocumentMultiSelect);
+
+		await userEvent.fill(page.getByPlaceholder('Dokument suchen…'), 'Eug');
+		await waitForDebounce();
+		await userEvent.click(page.getByText(/Brief von Eugenie/));
+
+		// After selection the search field clears and the chip is rendered
+		const hidden = document.querySelector<HTMLInputElement>(
+			'input[type="hidden"][name="documentIds"]'
+		);
+		expect(hidden?.value).toBe('d1');
+	});
+
+	it('hides already-selected documents from new search results', async () => {
+		const fetchMock = vi.fn().mockResolvedValue({
+			ok: true,
+			json: vi.fn().mockResolvedValue({
+				items: [
+					{ document: docFactory('d1', 'Already attached') },
+					{ document: docFactory('d2', 'Not attached') }
+				]
+			})
+		});
+		vi.stubGlobal('fetch', fetchMock);
+
+		render(DocumentMultiSelect, {
+			selectedDocuments: [docFactory('d1', 'Already attached')]
+		});
+
+		await userEvent.fill(page.getByPlaceholder('Dokument suchen…'), 'attached');
+		await waitForDebounce();
+
+		// "Not attached" appears in the dropdown; "Already attached" only as the chip.
+		const matches = await page.getByText(/Already attached/).all();
+		expect(matches.length).toBe(1); // chip only, not in dropdown
+		await expect.element(page.getByText(/Not attached/)).toBeInTheDocument();
+	});
+});
+
+describe('DocumentMultiSelect — remove', () => {
+	it('removes a chip when its × button is clicked', async () => {
+		render(DocumentMultiSelect, {
+			selectedDocuments: [docFactory('d1', 'Brief A')]
+		});
+		await userEvent.click(page.getByLabelText('Entfernen'));
+		expect(
+			document.querySelector<HTMLInputElement>('input[type="hidden"][name="documentIds"]')
+		).toBeNull();
+	});
+});