test: add test for res.destroyed handler

I had to use node's `http` module for this because
I could not get `supertest`s `abort` method to
work properly. With the raw `http` module I was able
to use `req.destroy()` to cancel the request early.
We now see the error from a premature closure, but are
still able to make extra requests afterwards

Author: jmcdo29

integration/send-files/e2e/express.spec.ts

@@ -5,6 +5,7 @@ import {
 import { Test } from '@nestjs/testing';
 import { expect } from 'chai';
 import { readFileSync } from 'fs';
+import * as http from 'http';
 import { join } from 'path';
 import * as request from 'supertest';
 import { AppModule } from '../src/app.module';
@@ -68,4 +69,44 @@ describe('Express FileSend', () => {
   it('should return an error if the file does not exist', async () => {
     return request(app.getHttpServer()).get('/file/not/exist').expect(400);
   });
+  it('should allow for the client to end the response and be able to make another', async () => {
+    await app.listen(0);
+    const url = await app.getUrl();
+    const [protocol, host, port] = url.replace('[::1]', 'localhost').split(':');
+    const httpOptions = {
+      host: host.replace('//', ''),
+      protocol: `${protocol}:`,
+      port,
+      path: '/file/slow',
+      method: 'GET',
+    };
+    await new Promise<void>(resolve => {
+      const req = http.request(httpOptions, res => {
+        res.on('data', () => {
+          req.destroy();
+        });
+        /* no op */
+        res.on('close', resolve);
+      });
+      req.end();
+    });
+    await new Promise<void>((resolve, reject) => {
+      const req = http.request(
+        { ...httpOptions, path: '/file/stream' },
+        res => {
+          res.on('data', chunk => {
+            /* no op */
+          });
+          res.on('error', err => {
+            reject(err);
+          });
+          res.on('end', () => {
+            expect(res.statusCode).to.be.eq(200);
+            resolve();
+          });
+        },
+      );
+      req.end();
+    });
+  }).timeout(5000);
 });

integration/send-files/src/app.controller.ts

@@ -36,4 +36,9 @@ export class AppController {
   getNonExistantFile(): StreamableFile {
     return this.appService.getFileThatDoesNotExist();
   }
+
+  @Get('/file/slow')
+  getSlowFile(): StreamableFile {
+    return this.appService.getSlowStream();
+  }
 }

integration/send-files/src/app.service.ts

@@ -1,7 +1,9 @@
 import { Injectable, StreamableFile } from '@nestjs/common';
+import { randomBytes } from 'crypto';
 import { createReadStream, readFileSync } from 'fs';
 import { join } from 'path';
 import { Observable, of } from 'rxjs';
+import { Readable } from 'stream';
 import { NonFile } from './non-file';
 
 @Injectable()
@@ -39,4 +41,11 @@ export class AppService {
   getFileThatDoesNotExist(): StreamableFile {
     return new StreamableFile(createReadStream('does-not-exist.txt'));
   }
+
+  getSlowStream(): StreamableFile {
+    const stream = new Readable();
+    stream.push(Buffer.from(randomBytes(Math.pow(2, 31) - 1)));
+    stream._read = () => {};
+    return new StreamableFile(stream);
+  }
 }