test(ArticleToc): addd snapshot testing

src/components/Article/ArticleToc.test.tsx

@@ -0,0 +1,29 @@
+import React from 'react';
+import { create, act } from 'react-test-renderer';
+import { render, fireEvent } from '@testing-library/react';
+import ArticleToc from './ArticleToc';
+
+describe('ArticleToc', () => {
+  const toc = 'Post Table of Contents';
+
+  test('should render correctly (snapshot)', () => {
+    const renderer = create(<ArticleToc toc={toc} />);
+    const tree = renderer.toJSON();
+    expect(tree).toMatchSnapshot();
+
+    const instance = renderer.root;
+    const tocButton = instance.find((node) => node.type === 'button');
+    act(() => tocButton.props.onClick());
+
+    const expandTree = renderer.toJSON();
+    expect(expandTree).toMatchSnapshot();
+  });
+
+  test('should expand ToC when clicked', () => {
+    const { getByRole, getByText } = render(<ArticleToc toc={toc} />);
+    const tocButton = getByRole('button');
+
+    fireEvent.click(tocButton);
+    expect(getByText(toc)).toBeInTheDocument();
+  });
+});