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Generate tests for the MCP plugin
Assisted-by: claude-4-sonnet Signed-off-by: John Collier <[email protected]>
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‎workspaces/mcp-integrations/plugins/backstage-mcp-plugin-backend/src/plugin.test.ts‎

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/*
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* Copyright 2025 The Backstage Authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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import { fetchCatalogEntities } from './plugin';
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import { CatalogService } from '@backstage/plugin-catalog-node';
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import { Entity } from '@backstage/catalog-model';
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describe('backstageMcpPlugin', () => {
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describe('fetchCatalogEntities function', () => {
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const mockCatalogService = {
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getEntities: jest.fn(),
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} as unknown as CatalogService;
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const mockAuthService = {
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getOwnServiceCredentials: jest.fn(),
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};
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beforeEach(() => {
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jest.clearAllMocks();
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});
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it('should fetch catalog entities successfully', async () => {
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const mockEntities: Entity[] = [
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{
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apiVersion: 'backstage.io/v1alpha1',
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kind: 'Component',
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metadata: {
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name: 'my-service',
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tags: ['java', 'spring'],
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},
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},
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{
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apiVersion: 'backstage.io/v1alpha1',
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kind: 'API',
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metadata: {
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name: 'my-api',
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tags: ['rest', 'openapi'],
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},
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},
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{
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apiVersion: 'backstage.io/v1alpha1',
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kind: 'System',
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metadata: {
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name: 'my-system',
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tags: [],
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},
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},
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];
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mockAuthService.getOwnServiceCredentials.mockResolvedValue({
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principal: { type: 'service', subject: 'test' },
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token: 'test-token',
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});
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(mockCatalogService.getEntities as jest.Mock).mockResolvedValue({
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items: mockEntities,
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});
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const result = await fetchCatalogEntities(
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mockCatalogService,
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mockAuthService,
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);
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expect(mockAuthService.getOwnServiceCredentials).toHaveBeenCalledTimes(1);
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expect(mockCatalogService.getEntities).toHaveBeenCalledWith(
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{
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fields: ['metadata.name', 'kind', 'metadata.tags'],
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},
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{
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credentials: {
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principal: { type: 'service', subject: 'test' },
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token: 'test-token',
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},
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},
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);
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expect(result).toEqual({
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entities: [
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{
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name: 'my-service',
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kind: 'Component',
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tags: ['java', 'spring'],
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},
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{
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name: 'my-api',
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kind: 'API',
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tags: ['rest', 'openapi'],
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},
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{
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name: 'my-system',
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kind: 'System',
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tags: [],
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},
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],
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});
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});
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it('should handle entities with no tags', async () => {
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const mockEntities: Entity[] = [
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{
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apiVersion: 'backstage.io/v1alpha1',
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kind: 'Component',
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metadata: {
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name: 'service-no-tags',
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},
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},
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];
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mockAuthService.getOwnServiceCredentials.mockResolvedValue({
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principal: { type: 'service', subject: 'test' },
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token: 'test-token',
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});
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(mockCatalogService.getEntities as jest.Mock).mockResolvedValue({
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items: mockEntities,
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});
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const result = await fetchCatalogEntities(
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mockCatalogService,
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mockAuthService,
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);
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expect(result).toEqual({
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entities: [
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{
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name: 'service-no-tags',
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kind: 'Component',
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tags: [],
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},
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],
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});
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});
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it('should handle empty catalog', async () => {
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mockAuthService.getOwnServiceCredentials.mockResolvedValue({
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principal: { type: 'service', subject: 'test' },
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token: 'test-token',
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});
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(mockCatalogService.getEntities as jest.Mock).mockResolvedValue({
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items: [],
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});
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const result = await fetchCatalogEntities(
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mockCatalogService,
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mockAuthService,
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);
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expect(result).toEqual({
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entities: [],
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});
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});
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it('should handle catalog service errors', async () => {
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mockAuthService.getOwnServiceCredentials.mockResolvedValue({
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principal: { type: 'service', subject: 'test' },
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token: 'test-token',
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});
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(mockCatalogService.getEntities as jest.Mock).mockRejectedValue(
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new Error('Catalog service error'),
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);
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await expect(
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fetchCatalogEntities(mockCatalogService, mockAuthService),
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).rejects.toThrow('Catalog service error');
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});
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it('should handle authentication errors', async () => {
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mockAuthService.getOwnServiceCredentials.mockRejectedValue(
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new Error('Authentication failed'),
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);
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await expect(
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fetchCatalogEntities(mockCatalogService, mockAuthService),
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).rejects.toThrow('Authentication failed');
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});
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});
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describe('MCP Action functions', () => {
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describe('greet-user action logic', () => {
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it('should generate personalized greeting', async () => {
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// Test the core logic of the greet-user action
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const greetUserAction = async ({
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input,
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}: {
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input: { name: string };
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}) => ({
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output: { greeting: `Hello ${input.name}!` },
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});
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const testCases = [
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{ input: { name: 'John Doe' }, expected: 'Hello John Doe!' },
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{ input: { name: '' }, expected: 'Hello !' },
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{ input: { name: 'José María' }, expected: 'Hello José María!' },
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{ input: { name: 'Alice123' }, expected: 'Hello Alice123!' },
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];
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for (const testCase of testCases) {
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const result = await greetUserAction(testCase);
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expect(result.output.greeting).toBe(testCase.expected);
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}
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});
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});
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describe('fetch-catalog-entities action logic', () => {
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it('should use fetchCatalogEntities function correctly', async () => {
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const mockCatalogService = {
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getEntities: jest.fn().mockResolvedValue({
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items: [
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{
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apiVersion: 'backstage.io/v1alpha1',
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kind: 'Component',
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metadata: {
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name: 'test-component',
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tags: ['test'],
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},
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},
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],
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}),
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} as unknown as CatalogService;
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const mockAuthService = {
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getOwnServiceCredentials: jest.fn().mockResolvedValue({
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principal: { type: 'service', subject: 'test' },
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token: 'test-token',
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}),
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};
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// Test the action logic
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const fetchCatalogEntitiesAction = async ({}) => ({
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output: await fetchCatalogEntities(
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mockCatalogService,
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mockAuthService,
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),
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});
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const result = await fetchCatalogEntitiesAction({});
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expect(result.output).toHaveProperty('entities');
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expect(Array.isArray(result.output.entities)).toBe(true);
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expect(result.output.entities).toHaveLength(1);
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expect(result.output.entities[0]).toEqual({
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name: 'test-component',
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kind: 'Component',
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tags: ['test'],
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});
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});
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});
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});
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describe('Action schemas and metadata', () => {
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it('should have correct greet-user action structure', () => {
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const greetUserActionDefinition = {
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name: 'greet-user',
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title: 'Greet User',
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description: 'Generate a personalized greeting',
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schema: {
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input: (z: any) =>
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z.object({
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name: z.string().describe('The name of the person to greet'),
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}),
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output: (z: any) =>
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z.object({
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greeting: z.string().describe('The generated greeting'),
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}),
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},
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};
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expect(greetUserActionDefinition.name).toBe('greet-user');
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expect(greetUserActionDefinition.title).toBe('Greet User');
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expect(greetUserActionDefinition.description).toBe(
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'Generate a personalized greeting',
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);
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expect(greetUserActionDefinition.schema.input).toBeDefined();
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expect(greetUserActionDefinition.schema.output).toBeDefined();
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});
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it('should have correct fetch-catalog-entities action structure', () => {
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const fetchCatalogEntitiesActionDefinition = {
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name: 'fetch-catalog-entities',
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title: 'Fetch Catalog Entities',
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description:
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'Retrieve the list of catalog entities from the Backstage server.',
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schema: {
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input: (z: any) => z.object({}),
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output: (z: any) =>
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z.object({
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entities: z
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.array(
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z.object({
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name: z
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.string()
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.describe(
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'The name field for each Backstage entity in the catalog',
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),
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kind: z
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.string()
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.describe(
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'The kind/type of the Backstage entity (e.g., Component, API, System)',
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),
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tags: z
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.array(z.string())
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.describe(
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'The tags associated with the Backstage entity',
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),
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}),
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)
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.describe('An array of entities'),
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}),
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},
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};
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expect(fetchCatalogEntitiesActionDefinition.name).toBe(
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'fetch-catalog-entities',
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);
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expect(fetchCatalogEntitiesActionDefinition.title).toBe(
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'Fetch Catalog Entities',
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);
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expect(fetchCatalogEntitiesActionDefinition.description).toBe(
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'Retrieve the list of catalog entities from the Backstage server.',
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);
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expect(fetchCatalogEntitiesActionDefinition.schema.input).toBeDefined();
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expect(fetchCatalogEntitiesActionDefinition.schema.output).toBeDefined();
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});
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});
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});

‎workspaces/mcp-integrations/plugins/backstage-mcp-plugin-backend/src/plugin.ts‎

Lines changed: 13 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -77,6 +77,16 @@ export const backstageMcpPlugin = createBackendPlugin({
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.describe(
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'The name field for each Backstage entity in the catalog',
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),
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kind: z
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.string()
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.describe(
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'The kind/type of the Backstage entity (e.g., Component, API, System)',
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),
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tags: z
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.array(z.string())
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.describe(
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'The tags associated with the Backstage entity',
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),
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}),
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)
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.describe('An array of entities'),
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const credentials = await auth.getOwnServiceCredentials();
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const { items } = await catalog.getEntities(
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{
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fields: ['metadata.name'],
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fields: ['metadata.name', 'kind', 'metadata.tags'],
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},
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{
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credentials,
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return {
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entities: items.map(entity => ({
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name: entity.metadata.name,
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kind: entity.kind,
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tags: entity.metadata.tags || [],
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})),
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};
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}

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