feat(preload): add file.list, file.pickFolder, file.pickFile convenience methods

tests/component/sidebar/Sidebar.test.tsx

@@ -1,10 +1,22 @@
-import { describe, it, expect, beforeEach } from 'vitest';
-import { render, screen } from '@testing-library/react';
+import { describe, it, expect, beforeEach, vi } from 'vitest';
+import { render, screen, fireEvent } from '@testing-library/react';
 import { ThemeProvider } from '@/components/theme-provider';
 import { Sidebar } from '@/components/sidebar/Sidebar';
 import { useFileStore } from '@/stores/file-store';
 import { useEditorStore } from '@/stores/editor-store';
 
+vi.mock('@/lib/ipc', () => ({
+  ipc: {
+    file: {
+      pickFolder: vi.fn(),
+      list: vi.fn(),
+      pickFile: vi.fn(),
+      read: vi.fn(),
+      write: vi.fn(),
+    },
+  },
+}));
+
 describe('Sidebar', () => {
   beforeEach(() => {
     useFileStore.setState({ tree: null, rootPath: null, expanded: new Set(), openTabs: [], activeTabId: null });
@@ -45,4 +57,36 @@ describe('Sidebar', () => {
     expect(screen.getByText('Outline')).toBeInTheDocument();
     expect(screen.getByText('README.md')).toBeInTheDocument();
   });
+
+  it('renders "Open Folder" button when no folder is open', () => {
+    useFileStore.setState({ tree: null, rootPath: null });
+
+    render(
+      <ThemeProvider defaultTheme="dark" attribute="class">
+        <Sidebar />
+      </ThemeProvider>
+    );
+
+    expect(screen.getByText(/no folder opened/i)).toBeInTheDocument();
+    const btn = screen.getByRole('button', { name: /open folder/i });
+    expect(btn).toBeInTheDocument();
+  });
+
+  it('clicking "Open Folder" button calls openFolderDialog', async () => {
+    const { ipc } = await import('@/lib/ipc');
+    const spy = vi.spyOn(useFileStore.getState(), 'openFolderDialog');
+
+    useFileStore.setState({ tree: null, rootPath: null });
+
+    render(
+      <ThemeProvider defaultTheme="dark" attribute="class">
+        <Sidebar />
+      </ThemeProvider>
+    );
+
+    const btn = screen.getByRole('button', { name: /open folder/i });
+    fireEvent.click(btn);
+
+    expect(spy).toHaveBeenCalled();
+  });
 });