1. Prevented a occurrence of the access violation exception during setting of the promise continuation callback;

2. Improved a unit tests to check the execution of promises.

Author: Taritsyn

src/JavaScriptEngineSwitcher.ChakraCore/ChakraCoreJsEngine.cs

@@ -61,6 +61,11 @@ public sealed class ChakraCoreJsEngine : JsEngineBase
 		/// </summary>
 		private JsObjectFinalizeCallback _externalObjectFinalizeCallback;
 
+		/// <summary>
+		/// Callback for continuation of promise
+		/// </summary>
+		private JsPromiseContinuationCallback _promiseContinuationCallback;
+
 		/// <summary>
 		/// List of native function callbacks
 		/// </summary>
@@ -125,6 +130,7 @@ public ChakraCoreJsEngine(ChakraCoreSettings settings)
 			}
 
 			_externalObjectFinalizeCallback = ExternalObjectFinalizeCallback;
+			_promiseContinuationCallback = PromiseContinuationCallback;
 
 			_dispatcher.Invoke(() =>
 			{
@@ -209,7 +215,7 @@ private JsScope CreateJsScope()
 
 			var jsScope = new JsScope(_jsContext);
 
-			JsRuntime.SetPromiseContinuationCallback(PromiseContinuationCallback, IntPtr.Zero);
+			JsRuntime.SetPromiseContinuationCallback(_promiseContinuationCallback, IntPtr.Zero);
 
 			return jsScope;
 		}
@@ -1349,6 +1355,7 @@ private void Dispose(bool disposing)
 						_nativeFunctions.Clear();
 					}
 
+					_promiseContinuationCallback = null;
 					_externalObjectFinalizeCallback = null;
 				}
 			}

test/JavaScriptEngineSwitcher.Tests/Es2015TestsBase.cs

@@ -12,34 +12,43 @@ public abstract class Es2015TestsBase : TestsBase
 		public virtual void ExecutionOfPromisesIsCorrect()
 		{
 			// Arrange
-			var sb = new StringBuilder();
+			var stringBuilder = new StringBuilder();
 			const string input = @"var successfulWork = new Promise(function(resolve, reject) {
-	resolve(""Resolved promise from JavaScript"");
+	resolve(""Success!"");
 });
 
 var unsuccessfulWork = new Promise(function (resolve, reject) {
-	reject(""Rejected promise from JavaScript"");
+	reject(""Fail!"");
 });
 
 function resolveCallback(result) {
-	console.AppendLine('Resolved: ' + result);
+	stringBuilder.AppendLine('Resolved: ' + result);
 }
 
 function rejectCallback(reason) {
-	console.AppendLine('Rejected: ' + reason);
+	stringBuilder.AppendLine('Rejected: ' + reason);
 }
 
 successfulWork.then(resolveCallback, rejectCallback);
 unsuccessfulWork.then(resolveCallback, rejectCallback);";
+			const string targetOutput = @"Resolved: Success!
+Rejected: Fail!
+";
 
 			// Act
+			string output;
+
 			using (var jsEngine = CreateJsEngine())
 			{
-				jsEngine.EmbedHostObject("sb", sb);
+				jsEngine.EmbedHostObject("stringBuilder", stringBuilder);
 				jsEngine.Execute(input);
+
+				output = stringBuilder.ToString();
+				stringBuilder.Clear();
 			}
 
 			// Assert
+			Assert.Equal(targetOutput, output);
 		}
 
 		#endregion