test: add error resilience tests for ResumePreviewForm (JhaSourav07#3521)

## Description

Fixes JhaSourav07#2698

Added error resilience test coverage for `ResumePreviewForm`.

### Tests Added

* Handles missing required fields gracefully
* Handles failed API responses with custom error messages
* Handles non-OK API responses with fallback error messages
* Handles network exceptions safely
* Verifies recovery after a failed request and successful retry

All tests pass locally with Vitest.

## Pillar

* [ ] 🎨 Pillar 1 — New Theme Design
* [ ] 📐 Pillar 2 — Geometric SVG Improvement
* [ ] 🕐 Pillar 3 — Timezone Logic Optimization
* [x] 🛠️ Other (Bug fix, refactoring, docs)

## Visual Preview

N/A (test-only changes)

## Checklist before requesting a review:

* [x] I have read the `CONTRIBUTING.md` file.
* [ ] I have tested these changes locally
(`localhost:3000/api/streak?user=YOUR_USERNAME`).
* [x] I have run `npm run format` and `npm run lint` locally and
resolved all errors (CI will fail otherwise).
* [x] My commits follow the Conventional Commits format (e.g.,
`feat(themes): ...`, `fix(calculate): ...`).
* [ ] I have updated `README.md` if I added a new theme or URL
parameter.
* [x] I have started the repo.
* [x] I have made sure that i have only one commit to merge in this PR.
* [ ] The SVG output matches the CommitPulse "premium quality" aesthetic
standard (no raw elements, smooth animations, correct fonts).
* [x] (Recommended) I joined the CommitPulse Discord community for
contributor discussions, mentorship, and faster PR support.

Author: JhaSourav07

components/dashboard/ResumePreviewForm.error-resilience.test.tsx

@@ -0,0 +1,177 @@
+import { render, screen, fireEvent, waitFor } from '@testing-library/react';
+import { describe, it, expect, vi, beforeEach } from 'vitest';
+import ResumePreviewForm from './ResumePreviewForm';
+import type { ReactNode, HTMLAttributes } from 'react';
+import '@testing-library/jest-dom';
+
+const toastMocks = vi.hoisted(() => ({
+  error: vi.fn(),
+  success: vi.fn(),
+}));
+
+vi.mock('sonner', () => ({
+  toast: {
+    error: toastMocks.error,
+    success: toastMocks.success,
+  },
+}));
+
+vi.mock('framer-motion', () => ({
+  motion: {
+    div: ({ children, ...props }: HTMLAttributes<HTMLDivElement> & { children?: ReactNode }) => (
+      <div {...props}>{children}</div>
+    ),
+  },
+}));
+
+const parsed = {
+  name: 'John Doe',
+  email: 'john@example.com',
+  phone: '1234567890',
+  skills: ['React'],
+  education: [],
+  experience: [],
+};
+
+describe('ResumePreviewForm - Error Resilience', () => {
+  const onBack = vi.fn();
+  const onComplete = vi.fn();
+
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  it('handles missing required fields gracefully', () => {
+    render(
+      <ResumePreviewForm
+        githubUsername="john"
+        parsed={{
+          ...parsed,
+          name: '',
+          email: '',
+        }}
+        fileName="resume.pdf"
+        onBack={onBack}
+        onComplete={onComplete}
+      />
+    );
+
+    fireEvent.click(screen.getByText('Save Profile'));
+
+    expect(toastMocks.error).toHaveBeenCalledWith('Name and email are required');
+
+    expect(onComplete).not.toHaveBeenCalled();
+  });
+
+  it('handles failed API responses with custom error message', async () => {
+    global.fetch = vi.fn().mockResolvedValue({
+      ok: true,
+      json: async () => ({
+        success: false,
+        error: 'Profile validation failed',
+      }),
+    }) as typeof fetch;
+
+    render(
+      <ResumePreviewForm
+        githubUsername="john"
+        parsed={parsed}
+        fileName="resume.pdf"
+        onBack={onBack}
+        onComplete={onComplete}
+      />
+    );
+
+    fireEvent.click(screen.getByText('Save Profile'));
+
+    await waitFor(() => {
+      expect(toastMocks.error).toHaveBeenCalledWith('Profile validation failed');
+    });
+
+    expect(onComplete).not.toHaveBeenCalled();
+  });
+
+  it('handles non-ok API responses with fallback error message', async () => {
+    global.fetch = vi.fn().mockResolvedValue({
+      ok: false,
+      json: async () => ({
+        success: false,
+      }),
+    }) as typeof fetch;
+
+    render(
+      <ResumePreviewForm
+        githubUsername="john"
+        parsed={parsed}
+        fileName="resume.pdf"
+        onBack={onBack}
+        onComplete={onComplete}
+      />
+    );
+
+    fireEvent.click(screen.getByText('Save Profile'));
+
+    await waitFor(() => {
+      expect(toastMocks.error).toHaveBeenCalledWith('Failed to save profile');
+    });
+
+    expect(onComplete).not.toHaveBeenCalled();
+  });
+
+  it('handles network exceptions safely', async () => {
+    global.fetch = vi.fn().mockRejectedValue(new Error('Network failure')) as typeof fetch;
+
+    render(
+      <ResumePreviewForm
+        githubUsername="john"
+        parsed={parsed}
+        fileName="resume.pdf"
+        onBack={onBack}
+        onComplete={onComplete}
+      />
+    );
+
+    fireEvent.click(screen.getByText('Save Profile'));
+
+    await waitFor(() => {
+      expect(toastMocks.error).toHaveBeenCalledWith('Network error. Please try again.');
+    });
+
+    expect(onComplete).not.toHaveBeenCalled();
+  });
+
+  it('recovers correctly after a failed request and allows successful retry', async () => {
+    global.fetch = vi
+      .fn()
+      .mockRejectedValueOnce(new Error('Network failure'))
+      .mockResolvedValueOnce({
+        ok: true,
+        json: async () => ({
+          success: true,
+        }),
+      }) as typeof fetch;
+
+    render(
+      <ResumePreviewForm
+        githubUsername="john"
+        parsed={parsed}
+        fileName="resume.pdf"
+        onBack={onBack}
+        onComplete={onComplete}
+      />
+    );
+
+    fireEvent.click(screen.getByText('Save Profile'));
+
+    await waitFor(() => {
+      expect(toastMocks.error).toHaveBeenCalledWith('Network error. Please try again.');
+    });
+
+    fireEvent.click(screen.getByText('Save Profile'));
+
+    await waitFor(() => {
+      expect(toastMocks.success).toHaveBeenCalledWith('Profile saved successfully!');
+      expect(onComplete).toHaveBeenCalled();
+    });
+  });
+});