catalog-backend: async response writing + tests and fixes

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

plugins/catalog-backend/src/service/createRouter.ts

@@ -171,7 +171,7 @@ export async function createRouter(
             res.setHeader('link', `<${url.pathname}${url.search}>; rel="next"`);
           }
 
-          writeEntitiesResponse(res, entities);
+          await writeEntitiesResponse(res, entities);
           return;
         }
 
@@ -253,7 +253,7 @@ export async function createRouter(
             credentials: await httpAuth.credentials(req),
           });
 
-        writeEntitiesResponse(res, items, entities => ({
+        await writeEntitiesResponse(res, items, entities => ({
           items: entities,
           totalItems,
           pageInfo: {
@@ -312,7 +312,9 @@ export async function createRouter(
           fields: parseEntityTransformParams(req.query, request.fields),
           credentials: await httpAuth.credentials(req),
         });
-        writeEntitiesResponse(res, items, entities => ({ items: entities }));
+        await writeEntitiesResponse(res, items, entities => ({
+          items: entities,
+        }));
       })
       .get('/entity-facets', async (req, res) => {
         const response = await entitiesCatalog.facets({

plugins/catalog-backend/src/service/response/write.test.ts

@@ -17,7 +17,7 @@
 import express from 'express';
 import { mockErrorHandler } from '@backstage/backend-test-utils';
 import request from 'supertest';
-import { writeSingleEntityResponse } from './write';
+import { writeEntitiesResponse, writeSingleEntityResponse } from './write';
 
 describe('writeSingleEntityResponse', () => {
   const app = express();
@@ -123,3 +123,159 @@ describe('writeSingleEntityResponse', () => {
     });
   });
 });
+
+describe('writeEntitiesResponse', () => {
+  const app = express();
+  app.use(express.json());
+  app.get('/echo', (req, res) => {
+    writeEntitiesResponse(res, req.body);
+  });
+  app.get('/wrapped', (req, res) => {
+    writeEntitiesResponse(res, req.body, entities => ({
+      page: 1,
+      items: entities,
+      totalItems: 1337,
+    }));
+  });
+  app.use(mockErrorHandler());
+
+  describe('in object form', () => {
+    it('should return empty list', async () => {
+      const res = await request(app).get('/echo').send({
+        type: 'object',
+        entities: [],
+      });
+
+      expect(res.status).toBe(200);
+      expect(res.type).toBe('application/json');
+      expect(res.header['content-type']).toBe(
+        'application/json; charset=utf-8',
+      );
+      expect(res.body).toEqual([]);
+    });
+
+    it('should return mixed objects', async () => {
+      const res = await request(app)
+        .get('/echo')
+        .send({
+          type: 'object',
+          entities: [{ kind: 'Component' }, null, { kind: 'User' }, null],
+        });
+
+      expect(res.status).toBe(200);
+      expect(res.type).toBe('application/json');
+      expect(res.header['content-type']).toBe(
+        'application/json; charset=utf-8',
+      );
+      expect(res.body).toEqual([
+        { kind: 'Component' },
+        null,
+        { kind: 'User' },
+        null,
+      ]);
+    });
+
+    it('should wrap response of empty list', async () => {
+      const res = await request(app)
+        .get('/wrapped')
+        .send({ type: 'object', entities: [] });
+
+      expect(res.status).toBe(200);
+      expect(res.type).toBe('application/json');
+      expect(res.header['content-type']).toBe(
+        'application/json; charset=utf-8',
+      );
+      expect(res.body).toEqual({ page: 1, items: [], totalItems: 1337 });
+    });
+
+    it('should wrap response of mixed list', async () => {
+      const res = await request(app)
+        .get('/wrapped')
+        .send({
+          type: 'object',
+          entities: [{ kind: 'Component' }, null, { kind: 'User' }, null],
+        });
+
+      expect(res.status).toBe(200);
+      expect(res.type).toBe('application/json');
+      expect(res.header['content-type']).toBe(
+        'application/json; charset=utf-8',
+      );
+      expect(res.body).toEqual({
+        page: 1,
+        items: [{ kind: 'Component' }, null, { kind: 'User' }, null],
+        totalItems: 1337,
+      });
+    });
+  });
+
+  describe('in raw form', () => {
+    it('should return empty list', async () => {
+      const res = await request(app).get('/echo').send({
+        type: 'raw',
+        entities: [],
+      });
+
+      expect(res.status).toBe(200);
+      expect(res.type).toBe('application/json');
+      expect(res.header['content-type']).toBe(
+        'application/json; charset=utf-8',
+      );
+      expect(res.body).toEqual([]);
+    });
+
+    it('should return mixed objects', async () => {
+      const res = await request(app)
+        .get('/echo')
+        .send({
+          type: 'raw',
+          entities: ['{"kind":"Component"}', null, '{"kind":"User"}', null],
+        });
+
+      expect(res.status).toBe(200);
+      expect(res.type).toBe('application/json');
+      expect(res.header['content-type']).toBe(
+        'application/json; charset=utf-8',
+      );
+      expect(res.body).toEqual([
+        { kind: 'Component' },
+        null,
+        { kind: 'User' },
+        null,
+      ]);
+    });
+
+    it('should wrap response of empty list', async () => {
+      const res = await request(app)
+        .get('/wrapped')
+        .send({ type: 'raw', entities: [] });
+
+      expect(res.status).toBe(200);
+      expect(res.type).toBe('application/json');
+      expect(res.header['content-type']).toBe(
+        'application/json; charset=utf-8',
+      );
+      expect(res.body).toEqual({ page: 1, items: [], totalItems: 1337 });
+    });
+
+    it('should wrap response of mixed list', async () => {
+      const res = await request(app)
+        .get('/wrapped')
+        .send({
+          type: 'raw',
+          entities: ['{"kind":"Component"}', null, '{"kind":"User"}', null],
+        });
+
+      expect(res.status).toBe(200);
+      expect(res.type).toBe('application/json');
+      expect(res.header['content-type']).toBe(
+        'application/json; charset=utf-8',
+      );
+      expect(res.body).toEqual({
+        page: 1,
+        items: [{ kind: 'Component' }, null, { kind: 'User' }, null],
+        totalItems: 1337,
+      });
+    });
+  });
+});

plugins/catalog-backend/src/service/response/write.ts

@@ -42,7 +42,7 @@ export function writeSingleEntityResponse(
   }
 }
 
-export function writeEntitiesResponse(
+export async function writeEntitiesResponse(
   res: Response,
   response: EntitiesResponseItems,
   responseWrapper?: (entities: JsonValue) => JsonValue,
@@ -63,7 +63,7 @@ export function writeEntitiesResponse(
   if (responseWrapper) {
     const marker = `__MARKER_${Math.random().toString(36).slice(2, 10)}__`;
     const wrapped = JSON.stringify(responseWrapper(marker));
-    const parts = wrapped.split(marker);
+    const parts = wrapped.split(`"${marker}"`);
     if (parts.length !== 2) {
       throw new Error(
         `Entity items response was incorrectly wrapped into ${parts.length} different parts`,
@@ -75,16 +75,18 @@ export function writeEntitiesResponse(
 
   let first = true;
   for (const entity of response.entities) {
-    if (first) {
-      res.write('[', 'utf8');
-      first = false;
-    } else {
-      res.write(',', 'utf8');
-    }
-    res.write(entity, 'utf8');
-  }
-  res.end(']');
-  if (trailing) {
-    res.write(trailing, 'utf8');
+    const prefix = first ? '[' : ',';
+    first = false;
+
+    await new Promise((resolve, reject) => {
+      res.write(prefix + entity, 'utf8', err => {
+        if (err) {
+          reject(err);
+        } else {
+          resolve(err);
+        }
+      });
+    });
   }
+  res.end(`${first ? '[' : ''}]${trailing}`);
 }