Custom mask for secret (#970)

* Masking Character added, not yet used.

* Setting the masking character can be chained with other extensions.

* Added string extension for masking, and replaced hardcoded asterisks.

* Check if mask is null first.

* Fixed Typo in previous test and added new test for custom masks.

* Added tests for masking with null character

* Added docs and example.

* Adjusted extensions so that Mask is integrated into Secret extension. Updated Exampls and Tests accordingly

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

@@ -5,7 +5,7 @@ namespace Spectre.Console;
 /// </summary>
 public static partial class AnsiConsoleExtensions
 {
-    internal static async Task<string> ReadLine(this IAnsiConsole console, Style? style, bool secret, IEnumerable<string>? items = null, CancellationToken cancellationToken = default)
+    internal static async Task<string> ReadLine(this IAnsiConsole console, Style? style, bool secret, char? mask, IEnumerable<string>? items = null, CancellationToken cancellationToken = default)
     {
         if (console is null)
         {
@@ -60,8 +60,9 @@ public static partial class AnsiConsoleExtensions
 
             if (!char.IsControl(key.KeyChar))
             {
-                text += key.KeyChar.ToString();
-                console.Write(secret ? "*" : key.KeyChar.ToString(), style);
+                text += key.KeyChar.ToString();
+                var output = key.KeyChar.ToString();
+                console.Write(secret ? output.Mask(mask) : output, style);
             }
         }
     }

src/Spectre.Console/Extensions/StringExtensions.cs

@@ -185,5 +185,28 @@ public static class StringExtensions
 #else
         return text.Contains(value, StringComparison.Ordinal);
 #endif
+    }
+
+    /// <summary>
+    /// "Masks" every character in a string.
+    /// </summary>
+    /// <param name="value">String value to mask.</param>
+    /// <param name="mask">Character to use for masking.</param>
+    /// <returns>Masked string.</returns>
+    public static string Mask(this string value, char? mask)
+    {
+        var output = string.Empty;
+
+        if (mask is null)
+        {
+            return output;
+        }
+
+        foreach (var c in value)
+        {
+            output += mask;
+        }
+
+        return output;
     }
 }