Adding support for intercepted element clicks in .NET

This adds a new exception, `ElementClickInterceptedException` to indicate
when an element is obscured by another element. This allows users to
distinguish between different causes of elements not being clickable.

Author: jimevans

dotnet/src/webdriver/ElementClickInterceptedException.cs

@@ -0,0 +1,73 @@
+// <copyright file="ElementClickInterceptedException.cs" company="WebDriver Committers">
+// Licensed to the Software Freedom Conservancy (SFC) under one
+// or more contributor license agreements. See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership. The SFC licenses this file
+// to you under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// </copyright>
+
+using System;
+using System.Runtime.Serialization;
+
+namespace OpenQA.Selenium
+{
+    /// <summary>
+    /// The exception that is thrown when an element is not visible.
+    /// </summary>
+    [Serializable]
+    public class ElementClickInterceptedException : ElementNotInteractableException
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="ElementNotInteractableException"/> class.
+        /// </summary>
+        public ElementClickInterceptedException()
+            : base()
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="ElementNotInteractableException"/> class with
+        /// a specified error message.
+        /// </summary>
+        /// <param name="message">The message that describes the error.</param>
+        public ElementClickInterceptedException(string message)
+            : base(message)
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="ElementNotInteractableException"/> class with
+        /// a specified error message and a reference to the inner exception that is the
+        /// cause of this exception.
+        /// </summary>
+        /// <param name="message">The error message that explains the reason for the exception.</param>
+        /// <param name="innerException">The exception that is the cause of the current exception,
+        /// or <see langword="null"/> if no inner exception is specified.</param>
+        public ElementClickInterceptedException(string message, Exception innerException)
+            : base(message, innerException)
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="ElementNotInteractableException"/> class with serialized data.
+        /// </summary>
+        /// <param name="info">The <see cref="SerializationInfo"/> that holds the serialized
+        /// object data about the exception being thrown.</param>
+        /// <param name="context">The <see cref="StreamingContext"/> that contains contextual
+        /// information about the source or destination.</param>
+        protected ElementClickInterceptedException(SerializationInfo info, StreamingContext context)
+            : base(info, context)
+        {
+        }
+    }
+}

dotnet/src/webdriver/Remote/RemoteWebDriver.cs

@@ -1380,6 +1380,9 @@ private static void UnpackAndThrowOnError(Response errorResponse)
                         case WebDriverResult.ObsoleteElement:
                             throw new StaleElementReferenceException(errorMessage);
 
+                        case WebDriverResult.ElementClickIntercepted:
+                            throw new ElementClickInterceptedException(errorMessage);
+
                         case WebDriverResult.ElementNotInteractable:
                             throw new ElementNotInteractableException(errorMessage);
 

dotnet/src/webdriver/Remote/WebDriverError.cs

@@ -203,6 +203,7 @@ public static WebDriverResult ResultFromError(string error)
         private static void InitializeResultMap()
         {
             resultMap = new Dictionary<string, WebDriverResult>();
+            resultMap[ElementClickIntercepted] = WebDriverResult.ElementClickIntercepted;
             resultMap[ElementNotSelectable] = WebDriverResult.ElementNotSelectable;
             resultMap[ElementNotVisible] = WebDriverResult.ElementNotDisplayed;
             resultMap[ElementNotInteractable] = WebDriverResult.ElementNotInteractable;