expressify: Do not send response when already sent

packages/middleware/src/expressify.test.ts

@@ -26,24 +26,46 @@ describe('expressify', () => {
         expressify(
           createMiddleware(ctx => (ctx.req as any).id = 'test')))
       app.get('/test', expressify(ctx => (ctx.req as any).id))
-      request(app)
+      await request(app)
       .get('/test')
       .expect(200)
       .expect('"test"')
     })
 
-    it('can send a response using a custom fn', () => {
+    it('can send a response using a custom fn', async () => {
       const app = express()
       app.use(
         expressify(
           createMiddleware(ctx => (ctx.req as any).id = 'test')))
       app.get('/test',
         expressify(ctx => (ctx.req as any).id, (res, value) => res.send(value)))
-      request(app)
+      await request(app)
       .get('/test')
       .expect(200)
       .expect('test')
     })
+
+    it('handles errors', async () => {
+      const app = express()
+      app.use(
+        expressify(
+          createMiddleware(ctx => { throw new Error('test') })))
+      await request(app)
+      .get('/test')
+      .expect(500)
+    })
+
+    it('does not crash nor hang when middleware sends a response', async () => {
+      const app = express()
+      app.use(
+        expressify(
+          createMiddleware(ctx => ctx.res.end('test'))))
+      await request(app)
+      .get('/test')
+      .expect(200)
+      .expect('test')
+    })
+
   })
 
 })

packages/middleware/src/expressify.ts

@@ -1,5 +1,4 @@
 import { NextFunction, Request, Response } from 'express'
-import { IncomingMessage, ServerResponse } from 'http'
 import { Middleware } from './Middleware'
 
 export const expressify = (
@@ -13,9 +12,7 @@ export const expressify = (
 ) => {
   let result: unknown
   try {
-    const r: IncomingMessage = req
-    const rr: ServerResponse = res
-    result = await handleMiddleware({req: r, res: rr})
+    result = await handleMiddleware({req, res})
   } catch (err) {
     next(err)
     return
@@ -24,5 +21,7 @@ export const expressify = (
     next()
     return
   }
-  sendResponse(res, result)
+  if (res.writable) {
+    sendResponse(res, result)
+  }
 }