test(briefwechsel): cover CorrespondenzPersonBar branches

Two PersonTypeahead inputs render, swap button visibility tied to
both-persons-set, sort button label/aria-pressed switch on DESC vs ASC,
document count rendering, sort and swap callback wirings.

9 tests covering ~25 branches.

Refs #496.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/routes/briefwechsel/CorrespondenzPersonBar.svelte.test.ts

@@ -0,0 +1,95 @@
+import { describe, it, expect, vi, afterEach } from 'vitest';
+import { cleanup, render } from 'vitest-browser-svelte';
+import { page } from 'vitest/browser';
+import CorrespondenzPersonBar from './CorrespondenzPersonBar.svelte';
+
+afterEach(cleanup);
+
+const baseProps = (overrides: Record<string, unknown> = {}) => ({
+	senderId: '',
+	receiverId: '',
+	initialSenderName: '',
+	initialReceiverName: '',
+	sortDir: 'DESC',
+	showAdvanced: false,
+	documentCount: 0,
+	onapplyFilters: () => {},
+	onswapPersons: () => {},
+	ontoggleSort: () => {},
+	ontoggleAdvanced: () => {},
+	...overrides
+});
+
+describe('CorrespondenzPersonBar', () => {
+	it('renders the two PersonTypeahead inputs', async () => {
+		render(CorrespondenzPersonBar, { props: baseProps() });
+
+		const inputs = document.querySelectorAll('input');
+		expect(inputs.length).toBeGreaterThanOrEqual(2);
+	});
+
+	it('hides the swap button when only one person is set', async () => {
+		render(CorrespondenzPersonBar, { props: baseProps({ senderId: 'p1' }) });
+
+		const swap = document.querySelector('[data-testid="conv-swap-btn"]') as HTMLElement;
+		expect(swap.classList.contains('opacity-0')).toBe(true);
+		expect(swap.tabIndex).toBe(-1);
+	});
+
+	it('shows the swap button when both senderId and receiverId are set', async () => {
+		render(CorrespondenzPersonBar, {
+			props: baseProps({ senderId: 'p1', receiverId: 'p2' })
+		});
+
+		const swap = document.querySelector('[data-testid="conv-swap-btn"]') as HTMLElement;
+		expect(swap.classList.contains('opacity-0')).toBe(false);
+		expect(swap.tabIndex).toBe(0);
+	});
+
+	it('renders the "Neueste" label when sortDir is DESC', async () => {
+		render(CorrespondenzPersonBar, { props: baseProps({ sortDir: 'DESC' }) });
+
+		await expect.element(page.getByText('Neueste')).toBeVisible();
+	});
+
+	it('renders the "Älteste" label when sortDir is ASC', async () => {
+		render(CorrespondenzPersonBar, { props: baseProps({ sortDir: 'ASC' }) });
+
+		await expect.element(page.getByText('Älteste')).toBeVisible();
+	});
+
+	it('marks the sort button as aria-pressed when sortDir is ASC', async () => {
+		render(CorrespondenzPersonBar, { props: baseProps({ sortDir: 'ASC' }) });
+
+		const sort = document.querySelector('[data-testid="conv-sort-btn"]') as HTMLElement;
+		expect(sort.getAttribute('aria-pressed')).toBe('true');
+	});
+
+	it('renders the document count', async () => {
+		render(CorrespondenzPersonBar, { props: baseProps({ documentCount: 42 }) });
+
+		await expect.element(page.getByText('42 Briefe')).toBeVisible();
+	});
+
+	it('calls ontoggleSort when the sort button is clicked', async () => {
+		const ontoggleSort = vi.fn();
+		render(CorrespondenzPersonBar, { props: baseProps({ ontoggleSort }) });
+
+		const sort = document.querySelector('[data-testid="conv-sort-btn"]') as HTMLElement;
+		sort.click();
+
+		expect(ontoggleSort).toHaveBeenCalledOnce();
+	});
+
+	it('calls onswapPersons when the swap button is clicked', async () => {
+		const onswapPersons = vi.fn();
+		render(CorrespondenzPersonBar, {
+			props: baseProps({ senderId: 'p1', receiverId: 'p2', onswapPersons })
+		});
+
+		const swap = document.querySelector('[data-testid="conv-swap-btn"]') as HTMLElement;
+		swap.click();
+
+		expect(onswapPersons).toHaveBeenCalledOnce();
+	});
+});