Implement PageError (#186)

Author: kblok

lib/PuppeteerSharp.Tests/Page/Events/ErrorTests.cs

@@ -20,4 +20,4 @@ public async Task ShouldThrowWhenPageCrashes()
             Assert.Equal("Page crashed!", error);
         }
     }
-}
+}

lib/PuppeteerSharp.Tests/Page/Events/PageErrorTests.cs

@@ -0,0 +1,33 @@
+
+using System;
+using System.Linq;
+using System.Collections.Generic;
+using System.Threading.Tasks;
+using Xunit;
+
+namespace PuppeteerSharp.Tests.Page.Events
+{
+    [Collection("PuppeteerLoaderFixture collection")]
+    public class PageErrorTests : PuppeteerPageBaseTest
+    {
+        [Fact]
+        public async Task ShouldFire()
+        {
+            string error = null;
+            void EventHandler(object sender, PageErrorEventArgs e)
+            {
+                error = e.Message;
+                Page.PageError -= EventHandler;
+            }
+
+            Page.PageError += EventHandler;
+
+            await Task.WhenAll(
+                Page.GoToAsync(TestConstants.ServerUrl + "/error.html"),
+                WaitForEvents(Page.Client, "Runtime.exceptionThrown")
+            );
+
+            Assert.Contains("Fancy", error);
+        }
+    }
+}

lib/PuppeteerSharp/Page.cs

@@ -91,6 +91,10 @@ private Page(Session client, Target target, FrameTree frameTree, bool ignoreHTTP
         public event EventHandler<RequestEventArgs> RequestCreated;
         public event EventHandler<RequestEventArgs> RequestFinished;
         public event EventHandler<RequestEventArgs> RequestFailed;
+        /// <summary>
+        /// Emitted when an uncaught exception happens within the page.
+        /// </summary>
+        public event EventHandler<PageErrorEventArgs> PageError;
 
         internal Session Client { get; }
 
@@ -172,7 +176,7 @@ public async Task<JSHandle> EvaluateExpressionHandleAsync(string script)
         /// <summary>
         /// Executes a script in browser context
         /// </summary>
-        /// <param name="script">Script to be evaluated in browser context</param>
+        /// <param name="pageFunction">Script to be evaluated in browser context</param>
         /// <remarks>
         /// If the script, returns a Promise, then the method would wait for the promise to resolve and return its value.
         /// <see cref="JSHandle"/> instances can be passed as arguments
@@ -538,7 +542,7 @@ public Task CloseAsync()
 
             return Task.CompletedTask;
         }
-        
+
         public Task<dynamic> EvaluateExpressionAsync(string script)
             => _frameManager.MainFrame.EvaluateExpressionAsync(script);
 
@@ -849,7 +853,25 @@ private async Task OnCertificateError(MessageEventArgs e)
         }
 
         private void HandleException(dynamic exceptionDetails)
+            => PageError?.Invoke(this, new PageErrorEventArgs(GetExceptionMessage(exceptionDetails)));
+
+        private string GetExceptionMessage(dynamic exceptionDetails)
         {
+            if (exceptionDetails.exception != null)
+            {
+                return exceptionDetails.exception.description;
+            }
+            var message = exceptionDetails.text;
+            if (exceptionDetails.stackTrace)
+            {
+                foreach (var callframe in exceptionDetails.stackTrace.callFrames)
+                {
+                    var location = $"{callframe.url}:{callframe.lineNumber}:{callframe.columnNumber}";
+                    var functionName = callframe.functionName || "<anonymous>";
+                    message += $"\n at {functionName} ({location})";
+                }
+            }
+            return message;
         }
 
         private void OnDialog(PageJavascriptDialogOpeningResponse message)

lib/PuppeteerSharp/PageErrorEventArgs.cs

@@ -0,0 +1,11 @@
+using System;
+
+namespace PuppeteerSharp
+{
+    public class PageErrorEventArgs : EventArgs
+    {
+        public string Message { get; set; }
+
+        public PageErrorEventArgs(string message) => Message = message;
+    }
+}