test(admin/tags): cover TagsListPanel branches

Tree label rendering, empty placeholder branch, top-level node
rendering, collapse-button visibility, autocollapse vs manual collapse
via localStorage, expand-on-click flow, localStorage parse path,
malformed-JSON resilience.

9 tests, ~25 branches.

Refs #496.

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

frontend/src/routes/admin/tags/TagsListPanel.svelte.test.ts

@@ -0,0 +1,79 @@
+import { describe, it, expect, afterEach, beforeEach } from 'vitest';
+import { cleanup, render } from 'vitest-browser-svelte';
+import { page } from 'vitest/browser';
+import TagsListPanel from './TagsListPanel.svelte';
+
+beforeEach(() => {
+	localStorage.clear();
+});
+
+afterEach(cleanup);
+
+const baseTree = [
+	{ id: 't1', name: 'Personen', parentId: null, color: 'sage', children: [] },
+	{ id: 't2', name: 'Orte', parentId: null, color: 'sienna', children: [] }
+];
+
+describe('TagsListPanel', () => {
+	it('renders the expanded panel with tree and label', async () => {
+		render(TagsListPanel, { props: { tree: baseTree } });
+
+		await expect.element(page.getByRole('tree', { name: /schlagwörter/i })).toBeVisible();
+	});
+
+	it('renders the empty placeholder when tree is empty', async () => {
+		render(TagsListPanel, { props: { tree: [] } });
+
+		await expect.element(page.getByText('Keine Schlagworte vorhanden.')).toBeVisible();
+	});
+
+	it('renders one tree node per top-level tag', async () => {
+		render(TagsListPanel, { props: { tree: baseTree } });
+
+		await expect.element(page.getByText('Personen')).toBeVisible();
+		await expect.element(page.getByText('Orte')).toBeVisible();
+	});
+
+	it('renders the collapse button in expanded view', async () => {
+		render(TagsListPanel, { props: { tree: baseTree } });
+
+		await expect.element(page.getByRole('button', { name: /liste einklappen/i })).toBeVisible();
+	});
+
+	it('renders collapsed view when autocollapse is true', async () => {
+		render(TagsListPanel, { props: { tree: baseTree, autocollapse: true } });
+
+		await expect.element(page.getByRole('button', { name: /liste ausklappen/i })).toBeVisible();
+	});
+
+	it('honours the localStorage manual-collapse preference', async () => {
+		localStorage.setItem('admin_tags_list_collapsed', 'true');
+		render(TagsListPanel, { props: { tree: baseTree } });
+
+		await expect.element(page.getByRole('button', { name: /liste ausklappen/i })).toBeVisible();
+	});
+
+	it('expands the panel when the collapsed handle is clicked', async () => {
+		localStorage.setItem('admin_tags_list_collapsed', 'true');
+		render(TagsListPanel, { props: { tree: baseTree } });
+
+		await page.getByRole('button', { name: /liste ausklappen/i }).click();
+
+		await expect.element(page.getByRole('tree')).toBeVisible();
+	});
+
+	it('reads the collapse map from localStorage on mount', async () => {
+		localStorage.setItem('admin_tags_tree_state', JSON.stringify({ t1: true }));
+		render(TagsListPanel, { props: { tree: baseTree } });
+
+		// Just verify it doesn't crash on JSON parse
+		await expect.element(page.getByRole('tree')).toBeVisible();
+	});
+
+	it('handles malformed localStorage tree state gracefully', async () => {
+		localStorage.setItem('admin_tags_tree_state', 'not-valid-json{');
+		render(TagsListPanel, { props: { tree: baseTree } });
+
+		await expect.element(page.getByRole('tree')).toBeVisible();
+	});
+});