fix 866: slight simplication of Argument<T> and Option<T> ctors, make them more congruent

Author: jonsequitur

src/System.CommandLine.Tests/ArgumentTests.cs

@@ -423,8 +423,7 @@ public void When_argument_cannot_be_parsed_as_the_specified_type_then_getting_va
                             argumentResult.ErrorMessage = $"'{argumentResult.Tokens.Single().Value}' is not an integer";
 
                             return default;
-                        }),
-                        Description = ""
+                        })
                     }
                 };
 

src/System.CommandLine.Tests/Help/HelpBuilderTests.cs

@@ -187,18 +187,16 @@ public void Usage_section_shows_arguments_if_there_are_arguments_for_command_whe
                            {
                                Name = "arg2",
                                Arity = new ArgumentArity(
-                                   minArityForArg2, 
+                                   minArityForArg2,
                                    maxArityForArg2)
-                           };
+            };
             var command = new Command("the-command", "command help")
             {
                 arg1,
                 arg2,
-                new Option(new[] { "-v", "--verbosity" })
-                {
-                    Description = "Sets the verbosity"
-                }
+                new Option(new[] { "-v", "--verbosity" }, "Sets the verbosity")
             };
+
             var rootCommand = new RootCommand();
             rootCommand.AddCommand(command);
 
@@ -479,8 +477,7 @@ public void Arguments_section_is_included_if_there_are_commands_with_arguments_c
                 new Argument
                 {
                     Name = "arg command name",
-                    Description = "test",
-                    Arity = ArgumentArity.ExactlyOne
+                    Description = "test"
                 }
             };
 

src/System.CommandLine.Tests/ParseDiagramTests.cs

@@ -78,15 +78,15 @@ public void Parse_diagram_identifies_options_where_default_values_have_been_appl
             {
                 new Option(new[] { "-h", "--height" })
                 {
-                    Argument = new Argument<int>(getDefaultValue: () => 10), Description = ""
+                    Argument = new Argument<int>(getDefaultValue: () => 10)
                 },
                 new Option(new[] { "-w", "--width" })
                 {
-                    Argument = new Argument<int>(getDefaultValue: () => 15), Description = ""
+                    Argument = new Argument<int>(getDefaultValue: () => 15)
                 },
                 new Option(new[] { "-c", "--color" })
                 {
-                    Argument = new Argument<ConsoleColor>(() => ConsoleColor.Cyan), Description = ""
+                    Argument = new Argument<ConsoleColor>(() => ConsoleColor.Cyan)
                 }
             };
 

src/System.CommandLine.Tests/ParseDirectiveTests.cs

@@ -29,7 +29,7 @@ public async Task Parse_directive_writes_parse_diagram()
             rootCommand.AddCommand(subcommand);
             var option = new Option(new[] { "-c", "--count" })
             {
-                Argument = new Argument<int>(), Description = ""
+                Argument = new Argument<int>()
             };
             subcommand.AddOption(option);
 

src/System.CommandLine/Argument{T}.cs

@@ -7,24 +7,32 @@ namespace System.CommandLine
 {
     public class Argument<T> : Argument
     {
-        public Argument(string name) : this()
+        public Argument() : base(null)
         {
-            Name = name;
+            ArgumentType = typeof(T);
         }
 
-        public Argument() : base(null)
+        public Argument(
+            string name, 
+            string description = null) : base(name)
         {
             ArgumentType = typeof(T);
+            Description = description;
         }
 
-        public Argument(string name, Func<T> getDefaultValue) : this(name)
+        public Argument(
+            string name, 
+            Func<T> getDefaultValue, 
+            string description = null) : this(name)
         {
             if (getDefaultValue == null)
             {
                 throw new ArgumentNullException(nameof(getDefaultValue));
             }
 
             SetDefaultValueFactory(() => getDefaultValue());
+
+            Description = description;
         }
 
         public Argument(Func<T> getDefaultValue) : this()

src/System.CommandLine/Option{T}.cs

@@ -7,22 +7,16 @@ namespace System.CommandLine
 {
     public class Option<T> : Option
     {
-        public Option(string alias) : base(alias)
-        {
-            Argument = new Argument<T>();
-        }
-
-        public Option(string[] aliases) : base(aliases)
-        {
-            Argument = new Argument<T>();
-        }
-
-        public Option(string alias, string description) : base(alias, description)
+        public Option(
+            string alias, 
+            string description = null) : base(alias, description)
         {
             Argument = new Argument<T>();
         }
 
-        public Option(string[] aliases, string description) : base(aliases, description)
+        public Option(
+            string[] aliases, 
+            string description = null) : base(aliases, description)
         {
             Argument = new Argument<T>();
         }