Adding test for IsRunning logic to return fast (#764)

Author: soninaren

src/WebJobs.Script.WebHost/Handlers/WebScriptHostHandler.cs

@@ -14,16 +14,17 @@ namespace Microsoft.Azure.WebJobs.Script.WebHost.Handlers
     public class WebScriptHostHandler : DelegatingHandler
     {
         private readonly TimeSpan _hostTimeoutSeconds;
-        private readonly int _hostRunningPollIntervalMs = 500;
+        private readonly int _hostRunningPollIntervalMs;
         private readonly HttpConfiguration _config;
 
-        public WebScriptHostHandler(HttpConfiguration config, int hostTimeoutSeconds = 30)
+        public WebScriptHostHandler(HttpConfiguration config, int hostTimeoutSeconds = 30, int hostRunningPollIntervalMS = 500)
         {
             if (config == null)
             {
                 throw new ArgumentNullException("config");
             }
 
+            _hostRunningPollIntervalMs = hostRunningPollIntervalMS;
             _hostTimeoutSeconds = new TimeSpan(0, 0, hostTimeoutSeconds);
             _config = config;
         }

src/WebJobs.Script/Host/ScriptHostManager.cs

@@ -63,7 +63,7 @@ public virtual ScriptHost Instance
         /// <summary>
         /// Gets the last host <see cref="Exception"/> that has occurred.
         /// </summary>
-        public Exception LastError { get; private set; }
+        public virtual Exception LastError { get; private set; }
 
         public void RunAndBlock(CancellationToken cancellationToken = default(CancellationToken))
         {

test/WebJobs.Script.Tests/WebScriptHostHandlerTests.cs

@@ -30,7 +30,7 @@ public WebScriptHostHandlerTests()
 
             HttpConfiguration config = new HttpConfiguration();
             config.DependencyResolver = mockResolver.Object;
-            WebScriptHostHandler handler = new WebScriptHostHandler(config, hostTimeoutSeconds: 1)
+            WebScriptHostHandler handler = new WebScriptHostHandler(config, hostTimeoutSeconds: 1, hostRunningPollIntervalMS: 50)
             {
                 InnerHandler = new TestHandler()
             };
@@ -41,6 +41,7 @@ public WebScriptHostHandlerTests()
         public async Task SendAsync_HostNotRunning_Returns503()
         {
             _managerMock.SetupGet(p => p.IsRunning).Returns(false);
+            _managerMock.SetupGet(p => p.LastError).Returns((Exception)null);
 
             HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Get, "http://functions.test.com/api/test");
             HttpResponseMessage response = await _invoker.SendAsync(request, CancellationToken.None);
@@ -57,6 +58,18 @@ public async Task SendAsync_HostRunning_ReturnsOk()
             Assert.Equal(HttpStatusCode.OK, response.StatusCode);
         }
 
+        [Fact]
+        public async Task SendAsync_HostInErrorState_Returns503Immediately()
+        {
+            _managerMock.SetupGet(p => p.IsRunning).Returns(false);
+            _managerMock.SetupGet(p => p.LastError).Returns(new Exception());
+
+            HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Get, "http://functions.test.com/api/test");
+            HttpResponseMessage response = await _invoker.SendAsync(request, CancellationToken.None);
+            Assert.Equal(HttpStatusCode.ServiceUnavailable, response.StatusCode);
+            _managerMock.VerifyGet(P => P.IsRunning, Times.Exactly(2));
+        }
+
         public class TestHandler : DelegatingHandler
         {
             protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)