Avoid null refs in BlazorIgntior when Disposed

docs/BuildFromSource.md

@@ -27,6 +27,7 @@ Building ASP.NET Core on Windows requires:
         ```ps1
         PS> ./eng/scripts/InstallJdk.ps1
         ```
+* Chrome - Selenium-based tests require a version of Chrome to be installed. Download and install it from [https://www.google.com/chrome]
 
 ### macOS/Linux
 

src/Components/Ignitor/src/BlazorClient.cs

@@ -88,7 +88,7 @@ public BlazorClient()
 
         public Task<CapturedRenderBatch> PrepareForNextBatch(TimeSpan? timeout)
         {
-            if (NextBatchReceived?.Completion != null)
+            if (NextBatchReceived != null && !NextBatchReceived.Disposed)
             {
                 throw new InvalidOperationException("Invalid state previous task not completed");
             }
@@ -100,7 +100,7 @@ public Task<CapturedRenderBatch> PrepareForNextBatch(TimeSpan? timeout)
 
         public Task<CapturedJSInteropCall> PrepareForNextJSInterop(TimeSpan? timeout)
         {
-            if (NextJSInteropReceived?.Completion != null)
+            if (NextJSInteropReceived != null && !NextJSInteropReceived.Disposed)
             {
                 throw new InvalidOperationException("Invalid state previous task not completed");
             }
@@ -112,7 +112,7 @@ public Task<CapturedJSInteropCall> PrepareForNextJSInterop(TimeSpan? timeout)
 
         public Task<string> PrepareForNextDotNetInterop(TimeSpan? timeout)
         {
-            if (NextDotNetInteropCompletionReceived?.Completion != null)
+            if (NextDotNetInteropCompletionReceived != null && !NextDotNetInteropCompletionReceived.Disposed)
             {
                 throw new InvalidOperationException("Invalid state previous task not completed");
             }
@@ -124,7 +124,7 @@ public Task<string> PrepareForNextDotNetInterop(TimeSpan? timeout)
 
         public Task<string> PrepareForNextCircuitError(TimeSpan? timeout)
         {
-            if (NextErrorReceived?.Completion != null)
+            if (NextErrorReceived != null && !NextErrorReceived.Disposed)
             {
                 throw new InvalidOperationException("Invalid state previous task not completed");
             }
@@ -136,7 +136,7 @@ public Task<string> PrepareForNextCircuitError(TimeSpan? timeout)
 
         public Task<Exception> PrepareForNextDisconnect(TimeSpan? timeout)
         {
-            if (NextDisconnect?.Completion != null)
+            if (NextDisconnect != null && !NextDisconnect.Disposed)
             {
                 throw new InvalidOperationException("Invalid state previous task not completed");
             }
@@ -499,56 +499,6 @@ public ElementNode FindElementById(string id)
             return element;
         }
 
-        private class CancellableOperation<TResult>
-        {
-            public CancellableOperation(TimeSpan? timeout)
-            {
-                Timeout = timeout;
-                Initialize();
-            }
-
-            public TimeSpan? Timeout { get; }
-
-            public TaskCompletionSource<TResult> Completion { get; set; }
-
-            public CancellationTokenSource Cancellation { get; set; }
-
-            public CancellationTokenRegistration CancellationRegistration { get; set; }
-
-            private void Initialize()
-            {
-                Completion = new TaskCompletionSource<TResult>(TaskContinuationOptions.RunContinuationsAsynchronously);
-                Completion.Task.ContinueWith(
-                    (task, state) =>
-                    {
-                        var operation = (CancellableOperation<TResult>)state;
-                        operation.Dispose();
-                    },
-                    this,
-                    TaskContinuationOptions.ExecuteSynchronously); // We need to execute synchronously to clean-up before anything else continues
-                if (Timeout != null && Timeout != System.Threading.Timeout.InfiniteTimeSpan && Timeout != TimeSpan.MaxValue)
-                {
-                    Cancellation = new CancellationTokenSource(Timeout.Value);
-                    CancellationRegistration = Cancellation.Token.Register(
-                        (self) =>
-                        {
-                            var operation = (CancellableOperation<TResult>)self;
-                            operation.Completion.TrySetCanceled(operation.Cancellation.Token);
-                            operation.Cancellation.Dispose();
-                            operation.CancellationRegistration.Dispose();
-                        },
-                        this);
-                }
-            }
-
-            private void Dispose()
-            {
-                Completion = null;
-                Cancellation.Dispose();
-                CancellationRegistration.Dispose();
-            }
-        }
-
         private string[] ReadMarkers(string content)
         {
             content = content.Replace("\r\n", "").Replace("\n", "");

src/Components/Ignitor/src/CancellableOperation.cs

@@ -0,0 +1,64 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Ignitor
+{
+    internal class CancellableOperation<TResult>
+    {
+        public CancellableOperation(TimeSpan? timeout)
+        {
+            Timeout = timeout;
+
+            Completion = new TaskCompletionSource<TResult>(TaskContinuationOptions.RunContinuationsAsynchronously);
+            Completion.Task.ContinueWith(
+                (task, state) =>
+                {
+                    var operation = (CancellableOperation<TResult>)state;
+                    operation.Dispose();
+                },
+                this,
+                TaskContinuationOptions.ExecuteSynchronously); // We need to execute synchronously to clean-up before anything else continues
+
+            if (Timeout != null && Timeout != System.Threading.Timeout.InfiniteTimeSpan && Timeout != TimeSpan.MaxValue)
+            {
+                Cancellation = new CancellationTokenSource(Timeout.Value);
+                CancellationRegistration = Cancellation.Token.Register(
+                    (self) =>
+                    {
+                        var operation = (CancellableOperation<TResult>)self;
+                        operation.Completion.TrySetCanceled(operation.Cancellation.Token);
+                        operation.Cancellation.Dispose();
+                        operation.CancellationRegistration.Dispose();
+                    },
+                    this);
+            }
+        }
+
+        public TimeSpan? Timeout { get; }
+
+        public TaskCompletionSource<TResult> Completion { get; }
+
+        public CancellationTokenSource Cancellation { get; }
+
+        public CancellationTokenRegistration CancellationRegistration { get; }
+
+        public bool Disposed { get; private set; }
+
+        private void Dispose()
+        {
+            if (Disposed)
+            {
+                return;
+            }
+
+            Disposed = true;
+            Completion.TrySetCanceled(Cancellation.Token);
+            Cancellation.Dispose();
+            CancellationRegistration.Dispose();
+        }
+    }
+}

src/Shared/E2ETesting/BrowserFixture.cs

@@ -108,7 +108,7 @@ public async Task DisposeAsync()
             var instance = await SeleniumStandaloneServer.GetInstanceAsync(output);
 
             var attempt = 0;
-            var maxAttempts = 3;
+            const int maxAttempts = 3;
             do
             {
                 try
@@ -132,18 +132,16 @@ public async Task DisposeAsync()
 
                     return (driver, logs);
                 }
-                catch
+                catch (Exception ex)
                 {
-                    if (attempt >= maxAttempts)
-                    {
-                        throw new InvalidOperationException("Couldn't create a Selenium remote driver client. The server is irresponsive");
-                    }
+                    output.WriteLine($"Error initializing RemoteWebDriver: {ex.Message}");
                 }
+
                 attempt++;
+
             } while (attempt < maxAttempts);
 
-            // We will never get here. Keeping the compiler happy.
-            throw new InvalidOperationException("Couldn't create a Selenium remote driver client. The server is unresponsive");
+            throw new InvalidOperationException("Couldn't create a Selenium remote driver client. The server is irresponsive");
         }
     }
 }