test: add tag ui components test

src/components/ui/Tag/index.test.tsx

@@ -0,0 +1,55 @@
+import { render } from '@testing-library/react';
+
+import '@testing-library/jest-dom';
+import { Tag } from '.'; // Replace with the correct path to your Tag component
+
+describe('ui/Tagのテスト', () => {
+  // Test rendering with default variant
+  it('renders the default variant of the tag correctly', () => {
+    const {
+      container: { firstChild },
+    } = render(<Tag />);
+    expect(firstChild).toHaveClass('bg-primary text-primary-foreground');
+  });
+
+  // Test rendering with 'secondary' variant
+  it('renders the secondary variant of the tag correctly', () => {
+    const {
+      container: { firstChild },
+    } = render(<Tag variant="secondary" />);
+    expect(firstChild).toHaveClass('bg-secondary text-secondary-foreground');
+  });
+
+  // Test rendering with 'outline' variant
+  it('renders the outline variant of the tag correctly', () => {
+    const {
+      container: { firstChild },
+    } = render(<Tag variant="outline" />);
+    expect(firstChild).toHaveClass('text-foreground');
+  });
+
+  // Test rendering as a Next.js Link
+  it('renders the tag as a Next.js Link', () => {
+    const {
+      container: { firstChild },
+    } = render(<Tag href="/test">test</Tag>);
+    expect(firstChild).toBeInTheDocument();
+    expect(firstChild).toHaveAttribute('href', '/test');
+  });
+
+  // Test that custom class names are applied properly
+  it('applies custom class names correctly', () => {
+    const customClassName = 'custom-class';
+    const {
+      container: { firstChild },
+    } = render(<Tag className={customClassName} />);
+    expect(firstChild).toHaveClass(customClassName);
+  });
+
+  // Test that children are rendered properly
+  it('renders children correctly', () => {
+    const text = 'Test Child';
+    const screen = render(<Tag>{text}</Tag>);
+    expect(screen.getByText(text)).toBeInTheDocument();
+  });
+});