[CCM-13003] Prevent templates being deleted when part of a message plan

frontend/src/__tests__/app/delete-template-error/[templateId]/__snapshots__/page.test.tsx.snap

@@ -0,0 +1,52 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`DeleteTemplateError page matches snapshot 1`] = `
+<DocumentFragment>
+  <main
+    class="nhsuk-main-wrapper"
+    id="maincontent"
+    role="main"
+  >
+    <div
+      class="nhsuk-grid-row"
+      data-testid="page-content-wrapper"
+    >
+      <div
+        class="nhsuk-grid-column-two-thirds"
+      >
+        <h1
+          class="nhsuk-heading-l"
+          data-testid="page-heading"
+        >
+          You cannot delete the template 'Test Template'
+        </h1>
+        <p>
+          The template is linked to these message plans:
+        </p>
+        <ul
+          class="nhsuk-list nhsuk-list--bullet"
+          data-testid="message-plan-list"
+        >
+          <li>
+            Email Campaign
+          </li>
+          <li>
+            SMS Notification
+          </li>
+        </ul>
+        <p>
+          You need to unlink it from each message plan before you can delete it.
+        </p>
+        <p>
+          <a
+            data-testid="back-link-bottom"
+            href="/message-templates"
+          >
+            Go back
+          </a>
+        </p>
+      </div>
+    </div>
+  </main>
+</DocumentFragment>
+`;

frontend/src/__tests__/app/delete-template-error/[templateId]/page.test.tsx

@@ -0,0 +1,137 @@
+import { render } from '@testing-library/react';
+import DeleteTemplateErrorPage, {
+  generateMetadata,
+} from '@app/delete-template-error/[templateId]/page';
+import { getTemplate } from '@utils/form-actions';
+import { getRoutingConfigReferencesByTemplateId } from '@utils/message-plans';
+import type {
+  TemplateDto,
+  RoutingConfigReference,
+} from 'nhs-notify-backend-client';
+import { redirect } from 'next/navigation';
+import { NextRedirectError } from '@testhelpers/next-redirect';
+import DeleteTemplateError from '@molecules/DeleteTemplateError/DeleteTemplateError';
+
+jest.mock('next/navigation', () => ({
+  redirect: jest.fn(),
+  RedirectType: { replace: 'replace', push: 'push' },
+}));
+
+jest.mocked(redirect).mockImplementation((url, type) => {
+  throw new NextRedirectError(url, type);
+});
+
+jest.mock('@utils/form-actions', () => ({
+  getTemplate: jest.fn(),
+}));
+
+jest.mock('@utils/message-plans', () => ({
+  getRoutingConfigReferencesByTemplateId: jest.fn(),
+}));
+
+const redirectMock = jest.mocked(redirect);
+const getTemplateMock = jest.mocked(getTemplate);
+const getRoutingConfigReferencesByTemplateIdMock = jest.mocked(
+  getRoutingConfigReferencesByTemplateId
+);
+
+const mockTemplate: Extract<TemplateDto, { templateType: 'NHS_APP' }> = {
+  id: 'template-123',
+  name: 'Test Template',
+  templateType: 'NHS_APP',
+  templateStatus: 'NOT_YET_SUBMITTED',
+  lockNumber: 1,
+  message: 'Test message',
+  createdAt: '2025-01-01T00:00:00.000Z',
+  updatedAt: '2025-01-01T00:00:00.000Z',
+};
+
+describe('DeleteTemplateError page', () => {
+  beforeEach(() => {
+    jest.clearAllMocks();
+  });
+
+  test('has correct page title', async () => {
+    const metadata = await generateMetadata();
+
+    expect(metadata).toEqual({
+      title: 'Delete template error - NHS Notify',
+    });
+  });
+
+  test('redirects when template is not found', async () => {
+    getTemplateMock.mockResolvedValueOnce(undefined);
+
+    await expect(
+      DeleteTemplateErrorPage({
+        params: Promise.resolve({ templateId: 'non-existent-template' }),
+      })
+    ).rejects.toThrow(NextRedirectError);
+
+    expect(getTemplateMock).toHaveBeenCalledWith('non-existent-template');
+    expect(getRoutingConfigReferencesByTemplateIdMock).not.toHaveBeenCalled();
+  });
+
+  test('redirects when no message plans are linked to template', async () => {
+    getTemplateMock.mockResolvedValueOnce(mockTemplate);
+    getRoutingConfigReferencesByTemplateIdMock.mockResolvedValueOnce([]);
+
+    await expect(
+      DeleteTemplateErrorPage({
+        params: Promise.resolve({ templateId: 'template-123' }),
+      })
+    ).rejects.toThrow(NextRedirectError);
+
+    expect(getTemplateMock).toHaveBeenCalledWith('template-123');
+    expect(getRoutingConfigReferencesByTemplateIdMock).toHaveBeenCalledWith(
+      'template-123'
+    );
+  });
+
+  test('displays error page when message plans are linked to template', async () => {
+    const messagePlans: RoutingConfigReference[] = [
+      { id: '90e46ece-4a3b-47bd-b781-f986b42a5a09', name: 'Message Plan 1' },
+      { id: 'a0e46ece-4a3b-47bd-b781-f986b42a5a10', name: 'Message Plan 2' },
+    ];
+
+    getTemplateMock.mockResolvedValueOnce(mockTemplate);
+    getRoutingConfigReferencesByTemplateIdMock.mockResolvedValueOnce(
+      messagePlans
+    );
+
+    const result = await DeleteTemplateErrorPage({
+      params: Promise.resolve({ templateId: 'template-123' }),
+    });
+
+    expect(getTemplateMock).toHaveBeenCalledWith('template-123');
+    expect(getRoutingConfigReferencesByTemplateIdMock).toHaveBeenCalledWith(
+      'template-123'
+    );
+    expect(redirectMock).not.toHaveBeenCalled();
+
+    expect(result).toEqual(
+      <DeleteTemplateError
+        templateName='Test Template'
+        messagePlans={messagePlans}
+      />
+    );
+  });
+
+  test('matches snapshot', async () => {
+    const messagePlans: RoutingConfigReference[] = [
+      { id: 'plan-1', name: 'Email Campaign' },
+      { id: 'plan-2', name: 'SMS Notification' },
+    ];
+
+    getTemplateMock.mockResolvedValueOnce(mockTemplate);
+    getRoutingConfigReferencesByTemplateIdMock.mockResolvedValueOnce(
+      messagePlans
+    );
+
+    const page = await DeleteTemplateErrorPage({
+      params: Promise.resolve({ templateId: 'template-789' }),
+    });
+
+    expect(render(page).asFragment()).toMatchSnapshot();
+  });
+});

frontend/src/__tests__/components/forms/DeleteTemplate/server-action.test.ts

@@ -8,12 +8,24 @@ import { setTemplateToDeleted } from '@utils/form-actions';
 
 jest.mock('next/navigation');
 jest.mock('@utils/form-actions');
+jest.mock('nhs-notify-web-template-management-utils/logger', () => ({
+  logger: {
+    error: jest.fn(),
+    info: jest.fn(),
+    warn: jest.fn(),
+    debug: jest.fn(),
+  },
+}));
 
 beforeAll(() => {
   jest.useFakeTimers();
   jest.setSystemTime(new Date('2022-01-01 09:00'));
 });
 
+beforeEach(() => {
+  jest.clearAllMocks();
+});
+
 test('redirects', async () => {
   const mockRedirect = jest.mocked(redirect);
 
@@ -49,3 +61,55 @@ test('calls form action and redirects', async () => {
     RedirectType.push
   );
 });
+
+test('redirects to error page when template is linked to message plans', async () => {
+  const mockSetTemplateToDeleted = jest.mocked(setTemplateToDeleted);
+  const mockRedirect = jest.mocked(redirect);
+
+  mockSetTemplateToDeleted.mockRejectedValueOnce(new Error('TEMPLATE_IN_USE'));
+
+  const mockTemplate: NHSAppTemplate = {
+    id: 'template-id',
+    name: 'template-name',
+    message: 'template-message',
+    templateType: 'NHS_APP',
+    templateStatus: 'NOT_YET_SUBMITTED',
+    createdAt: 'today',
+    updatedAt: 'today',
+    lockNumber: 1,
+  };
+
+  await deleteTemplateYesAction(mockTemplate);
+
+  expect(mockSetTemplateToDeleted).toHaveBeenCalledWith('template-id', 1);
+  expect(mockRedirect).toHaveBeenCalledWith(
+    '/delete-template-error/template-id',
+    RedirectType.push
+  );
+});
+
+test('rethrows other errors', async () => {
+  const mockSetTemplateToDeleted = jest.mocked(setTemplateToDeleted);
+  const mockRedirect = jest.mocked(redirect);
+
+  const unexpectedError = new Error('Database connection failed');
+  mockSetTemplateToDeleted.mockRejectedValueOnce(unexpectedError);
+
+  const mockTemplate: NHSAppTemplate = {
+    id: 'template-id',
+    name: 'template-name',
+    message: 'template-message',
+    templateType: 'NHS_APP',
+    templateStatus: 'NOT_YET_SUBMITTED',
+    createdAt: 'today',
+    updatedAt: 'today',
+    lockNumber: 1,
+  };
+
+  await expect(deleteTemplateYesAction(mockTemplate)).rejects.toThrow(
+    'Database connection failed'
+  );
+
+  expect(mockSetTemplateToDeleted).toHaveBeenCalledWith('template-id', 1);
+  expect(mockRedirect).not.toHaveBeenCalled();
+});

frontend/src/__tests__/components/molecules/DeleteTemplateError/DeleteTemplateError.test.tsx

@@ -0,0 +1,94 @@
+import { render, screen } from '@testing-library/react';
+import DeleteTemplateError from '@molecules/DeleteTemplateError/DeleteTemplateError';
+import type { RoutingConfigReference } from 'nhs-notify-backend-client';
+
+describe('DeleteTemplateError component', () => {
+  test('renders template name in heading', () => {
+    const messagePlans: RoutingConfigReference[] = [
+      { id: '90e46ece-4a3b-47bd-b781-f986b42a5a09', name: 'Test Message Plan' },
+    ];
+
+    render(
+      <DeleteTemplateError
+        templateName='Test Template'
+        messagePlans={messagePlans}
+      />
+    );
+
+    expect(
+      screen.getByText(/You cannot delete the template/)
+    ).toBeInTheDocument();
+
+    expect(screen.getByText(/'Test Template'/)).toBeInTheDocument();
+  });
+
+  test('renders single message plan', () => {
+    const messagePlans: RoutingConfigReference[] = [
+      { id: '90e46ece-4a3b-47bd-b781-f986b42a5a09', name: 'Single Plan' },
+    ];
+
+    render(
+      <DeleteTemplateError
+        templateName='My Template'
+        messagePlans={messagePlans}
+      />
+    );
+
+    expect(screen.getByText('Single Plan')).toBeInTheDocument();
+  });
+
+  test('renders multiple message plans', () => {
+    const messagePlans: RoutingConfigReference[] = [
+      { id: '90e46ece-4a3b-47bd-b781-f986b42a5a09', name: 'Message Plan 1' },
+      { id: 'a0e46ece-4a3b-47bd-b781-f986b42a5a10', name: 'Message Plan 2' },
+      { id: 'b0e46ece-4a3b-47bd-b781-f986b42a5a11', name: 'Message Plan 3' },
+    ];
+
+    const { container } = render(
+      <DeleteTemplateError
+        templateName='Test Template'
+        messagePlans={messagePlans}
+      />
+    );
+
+    expect(screen.getByText('Message Plan 1')).toBeInTheDocument();
+    expect(screen.getByText('Message Plan 2')).toBeInTheDocument();
+    expect(screen.getByText('Message Plan 3')).toBeInTheDocument();
+
+    const listItems = container.querySelectorAll('li');
+    expect(listItems.length).toBe(3);
+  });
+
+  test('renders back link', () => {
+    const messagePlans: RoutingConfigReference[] = [
+      { id: 'plan-1', name: 'Test Plan' },
+    ];
+
+    render(
+      <DeleteTemplateError
+        templateName='Test Template'
+        messagePlans={messagePlans}
+      />
+    );
+
+    const backLink = screen.getByTestId('back-link-bottom');
+    expect(backLink).toBeInTheDocument();
+    expect(backLink).toHaveAttribute('href', '/message-templates');
+  });
+
+  test('matches snapshot', () => {
+    const messagePlans: RoutingConfigReference[] = [
+      { id: '90e46ece-4a3b-47bd-b781-f986b42a5a09', name: 'Flu Campaign' },
+      { id: 'a0e46ece-4a3b-47bd-b781-f986b42a5a10', name: 'Covid Campaign' },
+    ];
+
+    const { asFragment } = render(
+      <DeleteTemplateError
+        templateName='Test Template'
+        messagePlans={messagePlans}
+      />
+    );
+
+    expect(asFragment()).toMatchSnapshot();
+  });
+});