test(ComparisonView): cover parts of the widget with tests

src/widgets/ComparisonView/ui/Header/Header.svelte.test.ts

@@ -0,0 +1,46 @@
+import {
+    fireEvent,
+    render,
+    screen,
+} from '@testing-library/svelte';
+import Header from './Header.svelte';
+
+const context = new Map([['responsive', { isMobile: false }]]);
+
+describe('Header', () => {
+    describe('Rendering', () => {
+        it('renders a header element', () => {
+            render(Header, { props: { isSidebarOpen: false, onSidebarToggle: () => {} }, context });
+            expect(document.querySelector('header')).toBeInTheDocument();
+        });
+
+        it('shows "Open Config" title when sidebar is closed', () => {
+            render(Header, { props: { isSidebarOpen: false, onSidebarToggle: () => {} }, context });
+            expect(screen.getByTitle('Open Config')).toBeInTheDocument();
+        });
+
+        it('shows "Close Config" title when sidebar is open', () => {
+            render(Header, { props: { isSidebarOpen: true, onSidebarToggle: () => {} }, context });
+            expect(screen.getByTitle('Close Config')).toBeInTheDocument();
+        });
+
+        it('renders a text input for the sample text', () => {
+            render(Header, { props: { isSidebarOpen: false, onSidebarToggle: () => {} }, context });
+            expect(screen.getByPlaceholderText('The quick brown fox...')).toBeInTheDocument();
+        });
+
+        it('renders the theme toggle button', () => {
+            render(Header, { props: { isSidebarOpen: false, onSidebarToggle: () => {} }, context });
+            expect(screen.getByTitle('Toggle theme')).toBeInTheDocument();
+        });
+    });
+
+    describe('Interaction', () => {
+        it('calls onSidebarToggle when toggle button is clicked', async () => {
+            const onSidebarToggle = vi.fn();
+            render(Header, { props: { isSidebarOpen: false, onSidebarToggle }, context });
+            await fireEvent.click(screen.getByTitle('Open Config'));
+            expect(onSidebarToggle).toHaveBeenCalledOnce();
+        });
+    });
+});