[dotnet] Add nullability annotations to ShadowRoot (#14812)

Author: RenderMichael

Diff for: dotnet/src/webdriver/ISearchContext.cs

@@ -20,6 +20,8 @@
 using System;
 using System.Collections.ObjectModel;
 
+#nullable enable
+
 namespace OpenQA.Selenium
 {
     /// <summary>

Diff for: dotnet/src/webdriver/IWrapsDriver.cs

@@ -17,6 +17,8 @@
 // under the License.
 // </copyright>
 
+#nullable enable
+
 namespace OpenQA.Selenium
 {
     /// <summary>

Diff for: dotnet/src/webdriver/Internal/IWebDriverObjectReference.cs

@@ -19,6 +19,8 @@
 
 using System.Collections.Generic;
 
+#nullable enable
+
 namespace OpenQA.Selenium.Internal
 {
     /// <summary>

Diff for: dotnet/src/webdriver/ShadowRoot.cs

@@ -21,6 +21,9 @@
 using System;
 using System.Collections.Generic;
 using System.Collections.ObjectModel;
+using System.Diagnostics.CodeAnalysis;
+
+#nullable enable
 
 namespace OpenQA.Selenium
 {
@@ -34,68 +37,67 @@ public class ShadowRoot : ISearchContext, IWrapsDriver, IWebDriverObjectReferenc
         /// </summary>
         public const string ShadowRootReferencePropertyName = "shadow-6066-11e4-a52e-4f735466cecf";
 
-        private WebDriver driver;
-        private string shadowRootId;
+        private readonly WebDriver driver;
+        private readonly string shadowRootId;
 
         /// <summary>
         /// Initializes a new instance of the <see cref="ShadowRoot"/> class.
         /// </summary>
         /// <param name="parentDriver">The <see cref="WebDriver"/> instance that is driving this shadow root.</param>
         /// <param name="id">The ID value provided to identify the shadow root.</param>
+        /// <exception cref="ArgumentNullException">If <paramref name="parentDriver"/> or <paramref name="id"/> are <see langword="null"/>.</exception>
         public ShadowRoot(WebDriver parentDriver, string id)
         {
-            this.driver = parentDriver;
-            this.shadowRootId = id;
+            this.driver = parentDriver ?? throw new ArgumentNullException(nameof(parentDriver));
+            this.shadowRootId = id ?? throw new ArgumentNullException(nameof(id));
         }
 
         /// <summary>
         /// Gets the <see cref="IWebDriver"/> driving this shadow root.
         /// </summary>
-        public IWebDriver WrappedDriver
-        {
-            get { return this.driver; }
-        }
+        public IWebDriver WrappedDriver => this.driver;
 
         /// <summary>
         /// Gets the internal ID for this ShadowRoot.
         /// </summary>
-        string IWebDriverObjectReference.ObjectReferenceId
-        {
-            get { return this.shadowRootId; }
-        }
+        string IWebDriverObjectReference.ObjectReferenceId => this.shadowRootId;
 
-        internal static bool ContainsShadowRootReference(Dictionary<string, object> shadowRootDictionary)
+        internal static bool TryCreate(WebDriver parentDriver, Dictionary<string, object?> shadowRootDictionary, [NotNullWhen(true)] out ShadowRoot? shadowRoot)
         {
-            if (shadowRootDictionary == null)
+            if (shadowRootDictionary is null)
             {
                 throw new ArgumentNullException(nameof(shadowRootDictionary), "The dictionary containing the shadow root reference cannot be null");
             }
 
-            return shadowRootDictionary.ContainsKey(ShadowRootReferencePropertyName);
-        }
+            if (shadowRootDictionary.TryGetValue(ShadowRootReferencePropertyName, out object? shadowRootValue))
+            {
+                shadowRoot = new ShadowRoot(parentDriver, shadowRootValue?.ToString()!);
+                return true;
+            }
 
-        internal static ShadowRoot FromDictionary(WebDriver driver, Dictionary<string, object> shadowRootDictionary)
-        {
-            return new ShadowRoot(driver, shadowRootDictionary[ShadowRoot.ShadowRootReferencePropertyName].ToString());
+            shadowRoot = null;
+            return false;
         }
 
         /// <summary>
         /// Finds the first <see cref="IWebElement"/> using the given method.
         /// </summary>
         /// <param name="by">The locating mechanism to use.</param>
         /// <returns>The first matching <see cref="IWebElement"/> on the current context.</returns>
+        /// <exception cref="ArgumentNullException">If <paramref name="by"/> is <see langword="null"/>.</exception>
         /// <exception cref="NoSuchElementException">If no element matches the criteria.</exception>
         public IWebElement FindElement(By by)
         {
-            if (by == null)
+            if (by is null)
             {
-                throw new ArgumentNullException(nameof(@by), "by cannot be null");
+                throw new ArgumentNullException(nameof(by), "by cannot be null");
             }
 
             Dictionary<string, object> parameters = new Dictionary<string, object>();
             parameters.Add("id", this.shadowRootId);
             parameters.Add("using", by.Mechanism);
             parameters.Add("value", by.Criteria);
+
             Response commandResponse = this.driver.InternalExecute(DriverCommand.FindShadowChildElement, parameters);
             return this.driver.GetElementFromResponse(commandResponse);
         }
@@ -107,26 +109,29 @@ public IWebElement FindElement(By by)
         /// <param name="by">The locating mechanism to use.</param>
         /// <returns>A <see cref="ReadOnlyCollection{T}"/> of all <see cref="IWebElement">WebElements</see>
         /// matching the current criteria, or an empty list if nothing matches.</returns>
+        /// <exception cref="ArgumentNullException">If <paramref name="by"/> is <see langword="null"/>.</exception>
         public ReadOnlyCollection<IWebElement> FindElements(By by)
         {
-            if (by == null)
+            if (by is null)
             {
-                throw new ArgumentNullException(nameof(@by), "by cannot be null");
+                throw new ArgumentNullException(nameof(by), "by cannot be null");
             }
 
             Dictionary<string, object> parameters = new Dictionary<string, object>();
             parameters.Add("id", this.shadowRootId);
             parameters.Add("using", by.Mechanism);
             parameters.Add("value", by.Criteria);
+
             Response commandResponse = this.driver.InternalExecute(DriverCommand.FindShadowChildElements, parameters);
             return this.driver.GetElementsFromResponse(commandResponse);
         }
 
         Dictionary<string, object> IWebDriverObjectReference.ToDictionary()
         {
-            Dictionary<string, object> shadowRootDictionary = new Dictionary<string, object>();
-            shadowRootDictionary.Add(ShadowRootReferencePropertyName, this.shadowRootId);
-            return shadowRootDictionary;
+            return new Dictionary<string, object>
+            {
+                [ShadowRootReferencePropertyName] = this.shadowRootId
+            };
         }
     }
 }

Diff for: dotnet/src/webdriver/WebDriver.cs

@@ -980,9 +980,9 @@ private object ParseJavaScriptReturnValue(object responseValue)
                 {
                     returnValue = this.elementFactory.CreateElement(resultAsDictionary);
                 }
-                else if (ShadowRoot.ContainsShadowRootReference(resultAsDictionary))
+                else if (ShadowRoot.TryCreate(this, resultAsDictionary, out ShadowRoot shadowRoot))
                 {
-                    returnValue = ShadowRoot.FromDictionary(this, resultAsDictionary);
+                    returnValue = shadowRoot;
                 }
                 else
                 {