test: cover api docs router behavior

src/routes/apiDocs.test.ts

@@ -0,0 +1,56 @@
+import express, { Express, NextFunction, Request, Response } from 'express';
+import path from 'path';
+import request from 'supertest';
+import { createApiDocsRouter } from './apiDocs';
+
+describe('createApiDocsRouter', () => {
+  let app: Express;
+
+  beforeEach(() => {
+    app = express();
+    app.use(createApiDocsRouter());
+  });
+
+  it('serves the OpenAPI specification', async () => {
+    const response = await request(app).get('/openapi.yaml');
+
+    expect(response.status).toBe(200);
+    expect(response.text).toContain('openapi: 3.0.0');
+    expect(response.text).toContain('title: Revora Backend API');
+  });
+
+  it('serves Swagger UI configured to load the OpenAPI specification', async () => {
+    const response = await request(app).get('/api-docs/');
+
+    expect(response.status).toBe(200);
+    expect(response.headers['content-type']).toMatch(/text\/html/);
+    expect(response.text).toContain('Swagger UI');
+    expect(response.text).toContain('/openapi.yaml');
+  });
+
+  it('returns not found for unsupported paths and methods', async () => {
+    const unknownPath = await request(app).get('/not-api-docs');
+    const unsupportedMethod = await request(app).post('/openapi.yaml');
+
+    expect(unknownPath.status).toBe(404);
+    expect(unsupportedMethod.status).toBe(404);
+  });
+
+  it('passes OpenAPI file errors to Express error middleware', async () => {
+    const resolveSpy = jest.spyOn(path, 'resolve').mockReturnValue('/missing/openapi.yaml');
+    try {
+      app = express();
+      app.use(createApiDocsRouter());
+    } finally {
+      resolveSpy.mockRestore();
+    }
+    app.use((error: NodeJS.ErrnoException, _req: Request, res: Response, _next: NextFunction) => {
+      res.status(500).json({ code: error.code });
+    });
+
+    const response = await request(app).get('/openapi.yaml');
+
+    expect(response.status).toBe(500);
+    expect(response.body).toEqual({ code: 'ENOENT' });
+  });
+});