test(success-guide): add massive scaling coverage for large markdown payloads

app/components/SuccessGuide.massive-scaling.test.tsx

@@ -0,0 +1,93 @@
+import { describe, it, expect, vi } from 'vitest';
+import { render, screen, fireEvent } from '@testing-library/react';
+import type { ReactNode } from 'react';
+import { SuccessGuide } from './SuccessGuide';
+
+vi.mock('framer-motion', () => ({
+  motion: {
+    div: ({ children, ...props }: { children?: ReactNode }) => <div {...props}>{children}</div>,
+  },
+}));
+
+vi.mock('./Icons', () => ({
+  CloseIcon: () => <span>CloseIcon</span>,
+}));
+
+vi.mock('@/context/TranslationContext', () => ({
+  useTranslation: () => ({
+    t: (key: string) => key,
+  }),
+}));
+
+describe('SuccessGuide massive scaling', () => {
+  const createLargeMarkdown = () =>
+    Array.from(
+      { length: 5000 },
+      (_, i) => `![badge-${i}](https://commitpulse.vercel.app/api/streak?user=user${i})`
+    ).join('\n');
+
+  it('renders extremely large markdown payloads without truncation', () => {
+    const markdown = createLargeMarkdown();
+
+    render(<SuccessGuide markdown={markdown} onDismiss={vi.fn()} />);
+
+    const codeElement = screen.getByLabelText('Your badge markdown snippet');
+
+    expect(codeElement.textContent).toBe(markdown);
+  });
+
+  it('preserves all guide steps when rendering large markdown content', () => {
+    const markdown = createLargeMarkdown();
+
+    render(<SuccessGuide markdown={markdown} onDismiss={vi.fn()} />);
+
+    expect(screen.getByText('01')).toBeInTheDocument();
+    expect(screen.getByText('02')).toBeInTheDocument();
+    expect(screen.getByText('03')).toBeInTheDocument();
+    expect(screen.getByText('04')).toBeInTheDocument();
+  });
+
+  it('renders repeatedly without layout instability', () => {
+    const markdown = createLargeMarkdown();
+
+    for (let i = 0; i < 100; i++) {
+      const { unmount } = render(<SuccessGuide markdown={markdown} onDismiss={vi.fn()} />);
+
+      expect(screen.getByRole('region')).toBeInTheDocument();
+
+      unmount();
+    }
+  });
+
+  it('maintains acceptable render performance under repeated mounts', () => {
+    const markdown = createLargeMarkdown();
+
+    const start = performance.now();
+
+    for (let i = 0; i < 50; i++) {
+      const { unmount } = render(<SuccessGuide markdown={markdown} onDismiss={vi.fn()} />);
+
+      unmount();
+    }
+
+    const duration = performance.now() - start;
+
+    expect(duration).toBeLessThan(5000);
+  });
+
+  it('keeps dismiss functionality stable under heavy rendering conditions', () => {
+    const onDismiss = vi.fn();
+
+    render(<SuccessGuide markdown={createLargeMarkdown()} onDismiss={onDismiss} />);
+
+    const dismissButton = screen.getByRole('button', {
+      name: /dismiss guide/i,
+    });
+
+    for (let i = 0; i < 25; i++) {
+      fireEvent.click(dismissButton);
+    }
+
+    expect(onDismiss).toHaveBeenCalledTimes(25);
+  });
+});