Add the actual command that generated the .cs file in the comments

Your colleagues and your future self will be happy to know exactly all the parameters that were used during generation when the C# source code must be regenerated for whatever reason.

Before:
```csharp
// This code was generated by XmlSchemaClassGenerator version 1.0.0.0.
```

After:
```csharp
// This code was generated by XmlSchemaClassGenerator version 1.0.0.0 using the following command:
// xscgen --namespace http://microsoft.com/schemas/VisualStudio/TeamTest/2010=vstst --collectionSettersMode=Public --collectionType=System.Array --nullable --pcl --verbose vstst.xsd
```

Author: 0xced

XmlSchemaClassGenerator.Tests/ExtensionsTests.cs

@@ -0,0 +1,17 @@
+using Xunit;
+
+namespace XmlSchemaClassGenerator.Tests
+{
+    public class ExtensionsTests
+    {
+        [Theory]
+        [InlineData(null, null)]
+        [InlineData("", "")]
+        [InlineData("MyText", "MyText")]
+        [InlineData("My Text", "\"My Text\"")]
+        public void QuoteEmptyOrNull(string input, string expected)
+        {
+            Assert.Equal(expected, input.QuoteIfNeeded());
+        }
+    }
+}

XmlSchemaClassGenerator.Tests/XmlTests.cs

@@ -1049,7 +1049,7 @@ public void ComplexTypeWithAttributeGroupExtension()
             var csharp = Assert.Single(contents);
 
             CompareOutput(
-                @"//------------------------------------------------------------------------------
+                $@"//------------------------------------------------------------------------------
 // <auto-generated>
 //     This code was generated by a tool.
 //
@@ -1058,46 +1058,47 @@ public void ComplexTypeWithAttributeGroupExtension()
 // </auto-generated>
 //------------------------------------------------------------------------------
 
-// This code was generated by Tests.
+// This code was generated by Tests using the following command:
+// {Extensions.GetFormattedCommandLineArgs()}
 namespace Test
-{
+{{
 
 
     [System.CodeDom.Compiler.GeneratedCodeAttribute(""Tests"", """")]
     [System.SerializableAttribute()]
     [System.Xml.Serialization.XmlTypeAttribute(""group-name"", Namespace="""")]
     [System.ComponentModel.DesignerCategoryAttribute(""code"")]
     public partial class Group_Name
-    {
+    {{
 
         /// <summary>
         /// <para xml:lang=""de"">Ruft den Text ab oder legt diesen fest.</para>
         /// <para xml:lang=""en"">Gets or sets the text value.</para>
         /// </summary>
         [System.Xml.Serialization.XmlTextAttribute()]
-        public string Value { get; set; }
+        public string Value {{ get; set; }}
 
         [System.Xml.Serialization.XmlAttributeAttribute(""justify"")]
-        public SimpleType Justify { get; set; }
+        public SimpleType Justify {{ get; set; }}
 
         /// <summary>
         /// <para xml:lang=""de"">Ruft einen Wert ab, der angibt, ob die Justify-Eigenschaft spezifiziert ist, oder legt diesen fest.</para>
         /// <para xml:lang=""en"">Gets or sets a value indicating whether the Justify property is specified.</para>
         /// </summary>
         [System.Xml.Serialization.XmlIgnoreAttribute()]
-        public bool JustifySpecified { get; set; }
-    }
+        public bool JustifySpecified {{ get; set; }}
+    }}
 
     [System.CodeDom.Compiler.GeneratedCodeAttribute(""Tests"", """")]
     [System.SerializableAttribute()]
     [System.Xml.Serialization.XmlTypeAttribute(""simpleType"", Namespace="""")]
     public enum SimpleType
-    {
+    {{
 
         [System.Xml.Serialization.XmlEnumAttribute(""foo"")]
         Foo,
-    }
-}
+    }}
+}}
 ", csharp);
         }
 

XmlSchemaClassGenerator/Extensions.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.IO;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
@@ -41,5 +42,26 @@ public static IEnumerable<TSource> DistinctBy<TSource, TKey>(this IEnumerable<TS
         {
             return source.GroupBy(propertySelector).Select(x => x.First());
         }
+
+        public static string GetFormattedCommandLineArgs()
+        {
+            var args = Environment.GetCommandLineArgs();
+            return string.Join(" ", args.Take(1).Select(Path.GetFileNameWithoutExtension).Concat(args.Skip(1)).Select(QuoteIfNeeded));
+        }
+
+        public static string QuoteIfNeeded(this string text)
+        {
+            if (string.IsNullOrEmpty(text))
+            {
+                return text;
+            }
+
+            if (text.Contains(" "))
+            {
+                return "\"" + text + "\"";
+            }
+
+            return text;
+        }
     }
 }

XmlSchemaClassGenerator/Generator.cs

@@ -329,9 +329,14 @@ public void Generate(XmlSchemaSet set)
             {
                 if (Version != null)
                 {
-                    var comment = $"This code was generated by {Version.Title}"
-                        + (CreateGeneratedCodeAttributeVersion ? $" version {Version.Version}." : ".");
-                    ns.Comments.Add(new CodeCommentStatement(comment));
+                    var comment = new StringBuilder($"This code was generated by {Version.Title}");
+                    if (CreateGeneratedCodeAttributeVersion)
+                    {
+                        comment.Append($" version {Version.Version}");
+                    }
+                    comment.Append(" using the following command:");
+                    ns.Comments.Add(new CodeCommentStatement(comment.ToString()));
+                    ns.Comments.Add(new CodeCommentStatement(Extensions.GetFormattedCommandLineArgs()));
                 }
 
                 writer.Write(ns);