Adding support for full-page screenshot command to .NET Firefox driver

Author: jimevans

dotnet/src/webdriver/Firefox/FirefoxDriver.cs

@@ -70,6 +70,7 @@ public class FirefoxDriver : RemoteWebDriver
         private const string SetContextCommand = "setContext";
         private const string InstallAddOnCommand = "installAddOn";
         private const string UninstallAddOnCommand = "uninstallAddOn";
+        private const string GetFullPageScreenshotCommand = "fullPageScreenshot";
 
         /// <summary>
         /// Initializes a new instance of the <see cref="FirefoxDriver"/> class.
@@ -153,6 +154,7 @@ public FirefoxDriver(FirefoxDriverService service, FirefoxOptions options, TimeS
             this.AddCustomFirefoxCommand(SetContextCommand, CommandInfo.PostCommand, "/session/{sessionId}/moz/context");
             this.AddCustomFirefoxCommand(InstallAddOnCommand, CommandInfo.PostCommand, "/session/{sessionId}/moz/addon/install");
             this.AddCustomFirefoxCommand(UninstallAddOnCommand, CommandInfo.PostCommand, "/session/{sessionId}/moz/addon/uninstall");
+            this.AddCustomFirefoxCommand(GetFullPageScreenshotCommand, CommandInfo.GetCommand, "/session/{sessionId}/moz/screenshot/full");
         }
 
         /// <summary>
@@ -242,6 +244,17 @@ public void UninstallAddOn(string addOnId)
             this.Execute(UninstallAddOnCommand, parameters);
         }
 
+        /// <summary>
+        /// Gets a <see cref="Screenshot"/> object representing the image of the full page on the screen.
+        /// </summary>
+        /// <returns>A <see cref="Screenshot"/> object containing the image.</returns>
+        public Screenshot GetFullPageScreenshot()
+        {
+            Response screenshotResponse = this.Execute(GetFullPageScreenshotCommand, null);
+            string base64 = screenshotResponse.Value.ToString();
+            return new Screenshot(base64);
+        }
+
         /// <summary>
         /// In derived classes, the <see cref="PrepareEnvironment"/> method prepares the environment for test execution.
         /// </summary>