Check worker runtime before warming up worker channels (#3859)

Author: pragnagopa

src/WebJobs.Script/Rpc/LanguageWorkerChannelManager.cs

@@ -85,6 +85,7 @@ public ILanguageWorkerChannel CreateLanguageWorkerChannel(string workerId, strin
 
         public Task InitializeAsync()
         {
+            _workerRuntime = _environment.GetEnvironmentVariable(LanguageWorkerConstants.FunctionWorkerRuntimeSettingName);
             if (SystemEnvironment.Instance.IsLinuxAppServiceEnvironment())
             {
                 return Task.CompletedTask;

test/WebJobs.Script.Tests.Integration/Rpc/LanguageWorkerChannelManagerEndToEndTests.cs

@@ -0,0 +1,40 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the MIT License. See License.txt in the project root for license information.
+
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Linq;
+using System.Threading.Tasks;
+using Microsoft.Azure.WebJobs.Script.Rpc;
+using Xunit;
+
+namespace Microsoft.Azure.WebJobs.Script.Tests
+{
+    public class LanguageWorkerChannelManagerEndToEndTests : IClassFixture<LanguageWorkerChannelManagerEndToEndTests.TestFixture>
+    {
+        private ILanguageWorkerChannelManager _languageWorkerChannelManager;
+        public LanguageWorkerChannelManagerEndToEndTests(TestFixture fixture)
+        {
+            Fixture = fixture;
+            _languageWorkerChannelManager = (ILanguageWorkerChannelManager) fixture.Host.Services.GetService(typeof(ILanguageWorkerChannelManager));
+            
+        }
+
+        public TestFixture Fixture { get; set; }
+
+        [Fact]
+        public void InitializeAsync_DoNotInitialize_JavaWorker()
+        {
+            var javaChannel = _languageWorkerChannelManager.GetChannel(LanguageWorkerConstants.JavaLanguageWorkerName);
+            Assert.Null(javaChannel);
+        }
+
+        public class TestFixture : ScriptHostEndToEndTestFixture
+        {
+            public TestFixture() : base(@"TestScripts\Node", "node", LanguageWorkerConstants.NodeLanguageWorkerName,
+                startHost: true, functions: new[] { "HttpTrigger" })
+            {
+            }
+        }
+    }
+}