Files
n8n-mcp/tests/unit/mcp/ui/meta-injection.test.ts
Romuald Członkowski 1f45cc6dcc feat: MCP Apps - rich HTML UIs for tool results (#573)
* feat: add MCP Apps with rich HTML UIs for tool results

Add MCP Apps infrastructure that allows MCP hosts like Claude Desktop
to render rich HTML UIs alongside tool results via `_meta.ui` and the
MCP resources protocol.

- Server-side UI module (src/mcp/ui/) with UIAppRegistry, tool-to-UI
  mapping, and _meta.ui injection into tool responses
- React + Vite build pipeline (ui-apps/) producing self-contained HTML
  per app using vite-plugin-singlefile
- Operation Result UI for workflow CRUD tools (create, update, delete,
  test, autofix, deploy)
- Validation Summary UI for validation tools (validate_node,
  validate_workflow, n8n_validate_workflow)
- Shared component library (Card, Badge, Expandable) with n8n dark theme
- MCP resources protocol support (ListResources, ReadResource handlers)
- Graceful degradation when ui-apps/dist/ is not built
- 22 unit tests across 3 test files

Conceived by Romuald Członkowski - https://www.aiadvisors.pl/en

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* test: improve MCP Apps test coverage and add security hardening

- Expand test suite from 22 to 57 tests across 3 test files
- Add UIAppRegistry.reset() for proper test isolation between tests
- Replace some fs mocks with real temp directory tests in registry
- Add edge case coverage: empty strings, pre-load state, double load,
  malformed URIs, duplicate tool patterns, empty HTML files
- Add regression tests for specific tool-to-UI mappings
- Add URI format consistency validation across all configs
- Improve _meta.ui injection tests with structuredContent coexistence
- Coverage: statements 79.4% -> 80%, lines 79.4% -> 80%

Conceived by Romuald Członkowski - https://www.aiadvisors.pl/en

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
2026-02-07 04:11:21 +01:00

215 lines
6.7 KiB
TypeScript

import { describe, it, expect, vi, beforeEach } from 'vitest';
import { UIAppRegistry } from '@/mcp/ui/registry';
vi.mock('fs', () => ({
existsSync: vi.fn(),
readFileSync: vi.fn(),
}));
import { existsSync, readFileSync } from 'fs';
const mockExistsSync = vi.mocked(existsSync);
const mockReadFileSync = vi.mocked(readFileSync);
describe('UI Meta Injection Logic', () => {
beforeEach(() => {
vi.clearAllMocks();
UIAppRegistry.reset();
});
describe('when HTML is loaded', () => {
beforeEach(() => {
mockExistsSync.mockReturnValue(true);
mockReadFileSync.mockReturnValue('<html>ui content</html>');
UIAppRegistry.load();
});
it('should add _meta.ui for matching tools', () => {
const uiApp = UIAppRegistry.getAppForTool('n8n_create_workflow');
expect(uiApp).not.toBeNull();
expect(uiApp!.html).not.toBeNull();
// Simulate the injection logic from server.ts
const mcpResponse: any = {
content: [{ type: 'text', text: 'result' }],
};
if (uiApp && uiApp.html) {
mcpResponse._meta = { ui: { app: uiApp.config.uri } };
}
expect(mcpResponse._meta).toBeDefined();
expect(mcpResponse._meta.ui.app).toBe('n8n-mcp://ui/operation-result');
});
it('should add _meta.ui for validation tools', () => {
const uiApp = UIAppRegistry.getAppForTool('validate_workflow');
expect(uiApp).not.toBeNull();
const mcpResponse: any = {
content: [{ type: 'text', text: 'validation result' }],
};
if (uiApp && uiApp.html) {
mcpResponse._meta = { ui: { app: uiApp.config.uri } };
}
expect(mcpResponse._meta).toBeDefined();
expect(mcpResponse._meta.ui.app).toBe('n8n-mcp://ui/validation-summary');
});
it('should NOT add _meta.ui for non-matching tools', () => {
const uiApp = UIAppRegistry.getAppForTool('get_node_info');
expect(uiApp).toBeNull();
const mcpResponse: any = {
content: [{ type: 'text', text: 'node info' }],
};
if (uiApp && uiApp.html) {
mcpResponse._meta = { ui: { app: uiApp.config.uri } };
}
expect(mcpResponse._meta).toBeUndefined();
});
it('should produce _meta with exact shape { ui: { app: string } }', () => {
const uiApp = UIAppRegistry.getAppForTool('n8n_create_workflow')!;
const meta = { ui: { app: uiApp.config.uri } };
expect(meta).toEqual({
ui: {
app: 'n8n-mcp://ui/operation-result',
},
});
expect(Object.keys(meta)).toEqual(['ui']);
expect(Object.keys(meta.ui)).toEqual(['app']);
expect(typeof meta.ui.app).toBe('string');
});
it('should produce _meta.ui.app that matches the config uri', () => {
const uiApp = UIAppRegistry.getAppForTool('validate_node')!;
const meta = { ui: { app: uiApp.config.uri } };
expect(meta.ui.app).toBe(uiApp.config.uri);
expect(meta.ui.app).toBe('n8n-mcp://ui/validation-summary');
});
});
describe('when HTML is not loaded', () => {
beforeEach(() => {
mockExistsSync.mockReturnValue(false);
UIAppRegistry.load();
});
it('should NOT add _meta.ui even for matching tools', () => {
const uiApp = UIAppRegistry.getAppForTool('n8n_create_workflow');
expect(uiApp).not.toBeNull();
expect(uiApp!.html).toBeNull();
const mcpResponse: any = {
content: [{ type: 'text', text: 'result' }],
};
if (uiApp && uiApp.html) {
mcpResponse._meta = { ui: { app: uiApp.config.uri } };
}
expect(mcpResponse._meta).toBeUndefined();
});
it('should NOT add _meta.ui for validation tools without HTML', () => {
const uiApp = UIAppRegistry.getAppForTool('validate_node');
expect(uiApp).not.toBeNull();
expect(uiApp!.html).toBeNull();
const mcpResponse: any = {
content: [{ type: 'text', text: 'result' }],
};
if (uiApp && uiApp.html) {
mcpResponse._meta = { ui: { app: uiApp.config.uri } };
}
expect(mcpResponse._meta).toBeUndefined();
});
});
describe('when registry has not been loaded at all', () => {
it('should NOT add _meta because getAppForTool returns null', () => {
// Registry never loaded - reset() was called in beforeEach
const uiApp = UIAppRegistry.getAppForTool('n8n_create_workflow');
expect(uiApp).toBeNull();
const mcpResponse: any = {
content: [{ type: 'text', text: 'result' }],
};
if (uiApp && uiApp.html) {
mcpResponse._meta = { ui: { app: uiApp.config.uri } };
}
expect(mcpResponse._meta).toBeUndefined();
});
});
describe('coexistence with structuredContent', () => {
beforeEach(() => {
mockExistsSync.mockReturnValue(true);
mockReadFileSync.mockReturnValue('<html>ui</html>');
UIAppRegistry.load();
});
it('should coexist with structuredContent on the response', () => {
const uiApp = UIAppRegistry.getAppForTool('n8n_create_workflow');
const mcpResponse: any = {
content: [{ type: 'text', text: 'result' }],
structuredContent: { workflowId: '123', status: 'created' },
};
if (uiApp && uiApp.html) {
mcpResponse._meta = { ui: { app: uiApp.config.uri } };
}
expect(mcpResponse.structuredContent).toBeDefined();
expect(mcpResponse.structuredContent.workflowId).toBe('123');
expect(mcpResponse._meta).toBeDefined();
expect(mcpResponse._meta.ui.app).toBe('n8n-mcp://ui/operation-result');
});
it('should not overwrite existing _meta properties when merging', () => {
const uiApp = UIAppRegistry.getAppForTool('n8n_create_workflow');
const mcpResponse: any = {
content: [{ type: 'text', text: 'result' }],
_meta: { existingProp: 'value' },
};
if (uiApp && uiApp.html) {
mcpResponse._meta = { ...mcpResponse._meta, ui: { app: uiApp.config.uri } };
}
expect(mcpResponse._meta.existingProp).toBe('value');
expect(mcpResponse._meta.ui.app).toBe('n8n-mcp://ui/operation-result');
});
it('should work with responses that have both structuredContent and existing _meta', () => {
const uiApp = UIAppRegistry.getAppForTool('validate_workflow');
const mcpResponse: any = {
content: [{ type: 'text', text: 'validation ok' }],
structuredContent: { valid: true, errors: [] },
_meta: { timing: 42 },
};
if (uiApp && uiApp.html) {
mcpResponse._meta = { ...mcpResponse._meta, ui: { app: uiApp.config.uri } };
}
expect(mcpResponse.structuredContent.valid).toBe(true);
expect(mcpResponse._meta.timing).toBe(42);
expect(mcpResponse._meta.ui.app).toBe('n8n-mcp://ui/validation-summary');
});
});
});