Merge pull request #13368 from ssilve1989/refactor/cleanup-grpc-call-handling

refactor(microservices): prevent grpc write promise from throwing

integration/microservices/e2e/math-grpc.spec.ts

@@ -4,11 +4,15 @@ import { INestApplication } from '@nestjs/common';
 import { MicroserviceOptions, Transport } from '@nestjs/microservices';
 import { Test } from '@nestjs/testing';
 import { fail } from 'assert';
-import { expect } from 'chai';
+import { expect, use } from 'chai';
+import * as chaiAsPromised from 'chai-as-promised';
 import { join } from 'path';
+import * as sinon from 'sinon';
 import * as request from 'supertest';
 import { GrpcController } from '../src/grpc/grpc.controller';
 
+use(chaiAsPromised);
+
 describe('GRPC transport', () => {
   let server;
   let app: INestApplication;
@@ -32,6 +36,7 @@ describe('GRPC transport', () => {
         ],
       },
     });
+
     // Start gRPC microservice
     await app.startAllMicroservices();
     await app.init();
@@ -149,6 +154,50 @@ describe('GRPC transport', () => {
     expect(receivedIds).to.deep.equal(expectedIds);
   });
 
+  describe('streaming calls that error', () => {
+    // We want to assert that the application does not crash when an error is encountered with an unhandledRejection
+    // the best way to do that is to listen for the unhandledRejection event and fail the test if it is called
+    let processSpy: sinon.SinonSpy;
+
+    beforeEach(() => {
+      processSpy = sinon.spy();
+      process.on('unhandledRejection', processSpy);
+    });
+
+    afterEach(() => {
+      process.off('unhandledRejection', processSpy);
+    });
+
+    it('should not crash when replying with an error', async () => {
+      const call = new Promise<void>((resolve, reject) => {
+        const stream = client.streamDivide({
+          data: [{ dividend: 1, divisor: 0 }],
+        });
+
+        stream.on('data', () => {
+          fail('Stream should not have emitted any data');
+        });
+
+        stream.on('error', err => {
+          if (err.code !== GRPC.status.CANCELLED) {
+            reject(err);
+          }
+        });
+
+        stream.on('end', () => {
+          resolve();
+        });
+      });
+
+      await expect(call).to.eventually.be.rejectedWith(
+        '3 INVALID_ARGUMENT: dividing by 0 is not possible',
+      );
+
+      // if this fails the application has crashed
+      expect(processSpy.called).to.be.false;
+    });
+  });
+
   after(async () => {
     await app.close();
   });

integration/microservices/src/grpc/grpc.controller.ts

@@ -10,7 +10,7 @@ import {
   RpcException,
 } from '@nestjs/microservices';
 import { join } from 'path';
-import { Observable, of, catchError } from 'rxjs';
+import { Observable, of, catchError, from, mergeMap } from 'rxjs';
 
 class ErrorHandlingProxy extends ClientGrpcProxy {
   serializeError(err) {
@@ -107,6 +107,17 @@ export class GrpcController {
     };
   }
 
+  // contrived example meant to show when an error is encountered, like dividing by zero, the
+  // application does not crash and the error is returned appropriately to the client
+  @GrpcMethod('Math', 'StreamDivide')
+  streamDivide({
+    data,
+  }: {
+    data: { dividend: number; divisor: number }[];
+  }): Observable<any> {
+    return from(data).pipe(mergeMap(request => this.divide(request)));
+  }
+
   @GrpcMethod('Math2')
   async sum2({ data }: { data: number[] }): Promise<any> {
     return of({

integration/microservices/src/grpc/math.proto

@@ -7,7 +7,9 @@ service Math {
   rpc SumStream(stream RequestSum) returns(stream SumResult);
   rpc SumStreamPass(stream RequestSum) returns(stream SumResult);
   rpc Divide (RequestDivide) returns (DivideResult);
-  rpc StreamLargeMessages(Empty) returns (stream BackpressureData) {}
+  rpc StreamLargeMessages(Empty) returns (stream BackpressureData);
+  /* Given a series of dividend and divisor, stream back the division results for each */
+  rpc StreamDivide (StreamDivideRequest) returns (stream StreamDivideResponse);
 }
 
 message BackpressureData {
@@ -33,3 +35,11 @@ message RequestDivide {
 message DivideResult {
   int32 result = 1;
 }
+
+message StreamDivideRequest {
+  repeated RequestDivide data = 1;
+}
+
+message StreamDivideResponse {
+  DivideResult data = 1;
+}