Fix error when output binding is null/undefined [v4] (#77)

Author: ejizba

src/InvocationModel.ts

@@ -13,6 +13,7 @@ import {
     RpcTypedData,
 } from '@azure/functions-core';
 import { format } from 'util';
+import { InvocationContext } from './InvocationContext';
 import { returnBindingKey } from './constants';
 import { fromRpcBindings } from './converters/fromRpcBindings';
 import { fromRpcRetryContext, fromRpcTraceContext } from './converters/fromRpcContext';
@@ -21,9 +22,8 @@ import { fromRpcTypedData } from './converters/fromRpcTypedData';
 import { toCamelCaseValue } from './converters/toCamelCase';
 import { toRpcHttp } from './converters/toRpcHttp';
 import { toRpcTypedData } from './converters/toRpcTypedData';
-import { InvocationContext } from './InvocationContext';
 import { isHttpTrigger, isTimerTrigger, isTrigger } from './utils/isTrigger';
-import { nonNullProp, nonNullValue } from './utils/nonNull';
+import { isDefined, nonNullProp, nonNullValue } from './utils/nonNull';
 
 export class InvocationModel implements coreTypes.InvocationModel {
     #isDone = false;
@@ -99,10 +99,10 @@ export class InvocationModel implements coreTypes.InvocationModel {
                     response.returnValue = await this.#convertOutput(binding, result);
                     usedReturnValue = true;
                 } else {
-                    response.outputData.push({
-                        name,
-                        data: await this.#convertOutput(binding, context.extraOutputs.get(name)),
-                    });
+                    const outputValue = await this.#convertOutput(binding, context.extraOutputs.get(name));
+                    if (isDefined(outputValue)) {
+                        response.outputData.push({ name, data: outputValue });
+                    }
                 }
             }
         }

test/InvocationModel.test.ts

@@ -0,0 +1,83 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the MIT License.
+
+import { RpcLogCategory, RpcLogLevel } from '@azure/functions-core';
+import { expect } from 'chai';
+import 'mocha';
+import { InvocationContext } from '../src';
+import { InvocationModel } from '../src/InvocationModel';
+
+function testLog(_level: RpcLogLevel, _category: RpcLogCategory, message: string) {
+    console.log(message);
+}
+
+describe('InvocationModel', () => {
+    describe('getResponse', () => {
+        it('Hello world http', async () => {
+            const model = new InvocationModel({
+                invocationId: 'testInvocId',
+                metadata: {
+                    name: 'testFuncName',
+                    bindings: {
+                        httpTrigger1: {
+                            type: 'httpTrigger',
+                            direction: 'in',
+                        },
+                        $return: {
+                            type: 'http',
+                            direction: 'out',
+                        },
+                    },
+                },
+                request: {},
+                log: testLog,
+            });
+            const context = new InvocationContext();
+            const response = await model.getResponse(context, { body: 'Hello, world!' });
+            expect(response).to.deep.equal({
+                invocationId: 'testInvocId',
+                outputData: [],
+                returnValue: {
+                    http: {
+                        body: {
+                            bytes: Buffer.from('Hello, world!'),
+                        },
+                        cookies: [],
+                        enableContentNegotiation: false,
+                        headers: {
+                            'content-type': 'text/plain;charset=UTF-8',
+                        },
+                        statusCode: '200',
+                    },
+                },
+            });
+        });
+
+        it('undefined output is not included in rpc response', async () => {
+            // https://github.com/Azure/azure-functions-nodejs-library/issues/71
+            // If an output binding is undefined or null, we should exclude it from the `outputData` array otherwise host will throw an error
+            // https://github.com/Azure/azure-functions-host/blob/6eea6da0952857b4cc64339f329cdf61432b5815/src/WebJobs.Script.Grpc/Channel/GrpcWorkerChannel.cs#L871
+            const model = new InvocationModel({
+                invocationId: 'testInvocId',
+                metadata: {
+                    name: 'testFuncName',
+                    bindings: {
+                        timerTrigger1: {
+                            type: 'timerTrigger',
+                            direction: 'in',
+                        },
+                        queueOutput1: {
+                            type: 'queue',
+                            direction: 'out',
+                        },
+                    },
+                },
+                request: {},
+                log: testLog,
+            });
+            const context = new InvocationContext();
+            const response = await model.getResponse(context, undefined);
+            expect(response).to.deep.equal({ invocationId: 'testInvocId', outputData: [], returnValue: undefined });
+        });
+    });
+});