Add default value parameter to Confirm extension

Closes #482

src/Spectre.Console/Extensions/AnsiConsoleExtensions.Prompt.cs

@@ -41,10 +41,15 @@ namespace Spectre.Console
         /// </summary>
         /// <param name="console">The console.</param>
         /// <param name="prompt">The prompt markup text.</param>
+        /// <param name="defaultValue">Specifies the default answer.</param>
         /// <returns><c>true</c> if the user selected "yes", otherwise <c>false</c>.</returns>
-        public static bool Confirm(this IAnsiConsole console, string prompt)
+        public static bool Confirm(this IAnsiConsole console, string prompt, bool defaultValue = true)
         {
-            return new ConfirmationPrompt(prompt).Show(console);
+            return new ConfirmationPrompt(prompt)
+            {
+                DefaultValue = defaultValue,
+            }
+            .Show(console);
         }
     }
 }

test/Spectre.Console.Tests/Unit/AnsiConsoleTests.Prompt.cs

@@ -0,0 +1,29 @@
+using System;
+using Shouldly;
+using Spectre.Console.Testing;
+using Xunit;
+
+namespace Spectre.Console.Tests.Unit
+{
+    public partial class AnsiConsoleTests
+    {
+        public sealed class Prompt
+        {
+            [Theory]
+            [InlineData(true, true)]
+            [InlineData(false, false)]
+            public void Should_Return_Default_Value_If_Nothing_Is_Entered(bool expected, bool defaultValue)
+            {
+                // Given
+                var console = new TestConsole().EmitAnsiSequences();
+                console.Input.PushKey(ConsoleKey.Enter);
+
+                // When
+                var result = console.Confirm("Want some prompt?", defaultValue);
+
+                // Then
+                result.ShouldBe(expected);
+            }
+        }
+    }
+}