Fix color system mapping bug

Closes #342

src/Spectre.Console.Testing/Fakes/FakeAnsiConsole.cs

@@ -21,7 +21,7 @@ namespace Spectre.Console.Testing
         IAnsiConsoleInput IAnsiConsole.Input => Input;
 
         public FakeAnsiConsole(
-            ColorSystem system,
+            ColorSystem colors,
             AnsiSupport ansi = AnsiSupport.Yes,
             int width = 80)
         {
@@ -32,7 +32,7 @@ namespace Spectre.Console.Testing
             _console = factory.Create(new AnsiConsoleSettings
             {
                 Ansi = ansi,
-                ColorSystem = (ColorSystemSupport)system,
+                ColorSystem = (ColorSystemSupport)colors,
                 Out = _writer,
                 Enrichment = new ProfileEnrichment
                 {

src/Spectre.Console.Tests/Unit/AnsiConsoleTests.Colors.cs

@@ -1,3 +1,4 @@
+using System.IO;
 using Shouldly;
 using Spectre.Console.Testing;
 using Xunit;
@@ -6,6 +7,25 @@ namespace Spectre.Console.Tests.Unit
 {
     public partial class AnsiConsoleTests
     {
+        [Theory]
+        [InlineData(ColorSystemSupport.NoColors, ColorSystem.NoColors)]
+        [InlineData(ColorSystemSupport.Legacy, ColorSystem.Legacy)]
+        [InlineData(ColorSystemSupport.Standard, ColorSystem.Standard)]
+        [InlineData(ColorSystemSupport.EightBit, ColorSystem.EightBit)]
+        [InlineData(ColorSystemSupport.TrueColor, ColorSystem.TrueColor)]
+        public void Should_Create_Console_With_Requested_ColorSystem(ColorSystemSupport requested, ColorSystem expected)
+        {
+            // Given, When
+            var console = AnsiConsole.Create(new AnsiConsoleSettings
+            {
+                ColorSystem = requested,
+                Out = new StringWriter(),
+            });
+
+            // Then
+            console.Profile.ColorSystem.ShouldBe(expected);
+        }
+
         public sealed class TrueColor
         {
             [Theory]

src/Spectre.Console.Tests/Unit/ColorSystemTests.cs

@@ -0,0 +1,23 @@
+using Shouldly;
+using Xunit;
+
+namespace Spectre.Console.Tests.Unit
+{
+    public sealed class ColorSystemTests
+    {
+        [Theory]
+        [InlineData(ColorSystem.NoColors, ColorSystemSupport.NoColors)]
+        [InlineData(ColorSystem.Legacy, ColorSystemSupport.Legacy)]
+        [InlineData(ColorSystem.Standard, ColorSystemSupport.Standard)]
+        [InlineData(ColorSystem.EightBit, ColorSystemSupport.EightBit)]
+        [InlineData(ColorSystem.TrueColor, ColorSystemSupport.TrueColor)]
+        public void Should_Be_Analog_To_ColorSystemSupport(ColorSystem colors, ColorSystemSupport support)
+        {
+            // Given, When
+            var result = (int)colors;
+
+            // Then
+            result.ShouldBe((int)support);
+        }
+    }
+}

src/Spectre.Console/AnsiConsoleFactory.cs

@@ -1,6 +1,5 @@
 using System;
 using System.Runtime.InteropServices;
-using System.Text;
 using Spectre.Console.Enrichment;
 using Spectre.Console.Internal;
 

src/Spectre.Console/AnsiConsoleSettings.cs

@@ -17,7 +17,7 @@ namespace Spectre.Console
         /// <summary>
         /// Gets or sets the color system to use.
         /// </summary>
-        public ColorSystemSupport ColorSystem { get; set; }
+        public ColorSystemSupport ColorSystem { get; set; } = ColorSystemSupport.Detect;
 
         /// <summary>
         /// Gets or sets the out buffer.

src/Spectre.Console/ColorSystemSupport.cs

@@ -8,31 +8,31 @@ namespace Spectre.Console
         /// <summary>
         /// Try to detect the color system.
         /// </summary>
-        Detect = 0,
+        Detect = -1,
 
         /// <summary>
         /// No colors.
         /// </summary>
-        NoColors = 1,
+        NoColors = 0,
 
         /// <summary>
         /// Legacy, 3-bit mode.
         /// </summary>
-        Legacy = 2,
+        Legacy = 1,
 
         /// <summary>
         /// Standard, 4-bit mode.
         /// </summary>
-        Standard = 3,
+        Standard = 2,
 
         /// <summary>
         /// 8-bit mode.
         /// </summary>
-        EightBit = 4,
+        EightBit = 3,
 
         /// <summary>
         /// 24-bit mode.
         /// </summary>
-        TrueColor = 5,
+        TrueColor = 4,
     }
 }