Improve WhatForRequest event detach (#1067)

Author: kblok

lib/PuppeteerSharp.Tests/PageTests/WaitForRequestTests.cs

@@ -1,8 +1,8 @@
 using System;
-using System.Net;
 using System.Threading.Tasks;
 using Xunit;
 using Xunit.Abstractions;
+using PuppeteerSharp.Helpers;
 
 namespace PuppeteerSharp.Tests.PageTests
 {
@@ -71,6 +71,27 @@ public async Task ShouldRespectDefaultTimeout()
             Assert.Contains("Timeout Exceeded: 1ms", exception.Message);
         }
 
+        [Fact]
+        public async Task ShouldProperyStopListeningNewRequests()
+        {
+            var tcs = new TaskCompletionSource<bool>();
+            await Page.GoToAsync(TestConstants.EmptyPage);
+            Page.DefaultTimeout = 1;
+            var exception = await Assert.ThrowsAnyAsync<TimeoutException>(async () =>
+                await Page.WaitForRequestAsync(request =>
+                {
+                    if (request.Url.Contains("/digits/1.png"))
+                    {
+                        tcs.TrySetResult(true);
+                    }
+
+                    return true;
+                }));
+
+            await Page.EvaluateFunctionAsync(@"() => fetch('/digits/1.png')");
+            await Assert.ThrowsAnyAsync<TimeoutException>(() => tcs.Task.WithTimeout(1));
+        }
+
         [Fact]
         public async Task ShouldWorkWithNoTimeout()
         {

lib/PuppeteerSharp/Page.cs

@@ -1438,7 +1438,11 @@ void requestEventListener(object sender, RequestEventArgs e)
 
             _networkManager.Request += requestEventListener;
 
-            return await requestTcs.Task.WithTimeout(timeout).ConfigureAwait(false);
+            return await requestTcs.Task.WithTimeout(timeout, t =>
+            {
+                _networkManager.Request -= requestEventListener;
+                return new TimeoutException($"Timeout Exceeded: {t.TotalMilliseconds}ms exceeded");
+            }).ConfigureAwait(false);
         }
 
         /// <summary>