Add tests for Breadcrumbs (#53514)

public/app/core/components/Breadcrumbs/Breadcrumbs.test.tsx

@@ -0,0 +1,43 @@
+import { render, screen, within } from '@testing-library/react';
+import React from 'react';
+
+import { Breadcrumbs } from './Breadcrumbs';
+import { Breadcrumb } from './types';
+
+const mockBreadcrumbs: Breadcrumb[] = [
+  { text: 'Home', href: '/home', icon: 'home-alt' },
+  { text: 'First', href: '/first' },
+  { text: 'Second', href: '/second' },
+];
+
+describe('Breadcrumbs', () => {
+  it('should render without error', () => {
+    expect(() => render(<Breadcrumbs breadcrumbs={[]} />)).not.toThrow();
+  });
+
+  it('should render a <nav> element', () => {
+    render(<Breadcrumbs breadcrumbs={[]} />);
+    expect(screen.getByRole('navigation')).toBeInTheDocument();
+  });
+
+  it('should render links for each breadcrumb except the last', () => {
+    render(<Breadcrumbs breadcrumbs={mockBreadcrumbs} />);
+    const nav = screen.getByRole('navigation');
+    const links = within(nav).getAllByRole('link');
+    expect(links.length).toEqual(2);
+    const homeLink = within(nav).getByRole('link', { name: 'Home' });
+    expect(homeLink).toBeInTheDocument();
+    expect(homeLink).toHaveAttribute('href', '/home');
+    const firstLink = within(nav).getByRole('link', { name: 'First' });
+    expect(firstLink).toBeInTheDocument();
+    expect(firstLink).toHaveAttribute('href', '/first');
+  });
+
+  it('should render the last breadcrumb as text and set the correct aria-current attribute', () => {
+    render(<Breadcrumbs breadcrumbs={mockBreadcrumbs} />);
+    const nav = screen.getByRole('navigation');
+    expect(within(nav).queryByRole('link', { name: 'Second' })).not.toBeInTheDocument();
+    expect(within(nav).getByText('Second')).toBeInTheDocument();
+    expect(within(nav).getByText('Second')).toHaveAttribute('aria-current', 'page');
+  });
+});