fix #2622: add ArgumentResult.Implicit property (#2625)

* fix #2622: add ArgumentResult.Implicit property

* some code cleanup

Author: jonsequitur

src/System.CommandLine.ApiCompatibility.Tests/ApiCompatibilityApprovalTests.System_CommandLine_api_is_not_changed.approved.txt

@@ -200,6 +200,7 @@ System.CommandLine.Invocation
 System.CommandLine.Parsing
   public class ArgumentResult : SymbolResult
     public System.CommandLine.Argument Argument { get; }
+    public System.Boolean Implicit { get; }
     public System.Void AddError(System.String errorMessage)
     public T GetValueOrDefault<T>()
     public System.Void OnlyTake(System.Int32 numberOfTokens)

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

@@ -258,8 +258,8 @@ public void Option_can_fallback_to_default_when_customizing(bool conditionA, boo
 
             var helpBuilder = new HelpBuilder(LargeMaxWidth);
             helpBuilder.CustomizeSymbol(option,
-                                        firstColumnText: ctx => conditionA ? "custom 1st" : HelpBuilder.Default.GetOptionUsageLabel(option),
-                                        secondColumnText: ctx => conditionB ? "custom 2nd" : option.Description ?? string.Empty);
+                                        firstColumnText: _ => conditionA ? "custom 1st" : HelpBuilder.Default.GetOptionUsageLabel(option),
+                                        secondColumnText: _ => conditionB ? "custom 2nd" : option.Description ?? string.Empty);
 
             command.Options.Add(new HelpOption
             {
@@ -300,9 +300,9 @@ public void Argument_can_fallback_to_default_when_customizing(
 
             var helpBuilder = new HelpBuilder(LargeMaxWidth);
             helpBuilder.CustomizeSymbol(argument,
-                                        firstColumnText: ctx => conditionA ? "custom 1st" : HelpBuilder.Default.GetArgumentUsageLabel(argument),
-                                        secondColumnText: ctx => conditionB ? "custom 2nd" : HelpBuilder.Default.GetArgumentDescription(argument),
-                                        defaultValue: ctx => conditionC ? "custom def" : HelpBuilder.Default.GetArgumentDefaultValue(argument));
+                                        firstColumnText: _ => conditionA ? "custom 1st" : HelpBuilder.Default.GetArgumentUsageLabel(argument),
+                                        secondColumnText: _ => conditionB ? "custom 2nd" : HelpBuilder.Default.GetArgumentDescription(argument),
+                                        defaultValue: _ => conditionC ? "custom def" : HelpBuilder.Default.GetArgumentDefaultValue(argument));
 
             command.Options.Add(new HelpOption
             {

src/System.CommandLine.Tests/HelpOptionTests.cs

@@ -2,7 +2,6 @@
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
 using FluentAssertions;
-using Microsoft.VisualStudio.TestPlatform.Utilities;
 using System.CommandLine.Help;
 using System.CommandLine.Invocation;
 using System.CommandLine.Tests.Utility;

src/System.CommandLine.Tests/OptionTests.MultipleArgumentsPerToken.cs

@@ -1,7 +1,6 @@
 // Copyright (c) .NET Foundation and contributors. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
-using System.CommandLine.Parsing;
 using System.CommandLine.Tests.Utility;
 using FluentAssertions;
 using System.Linq;

src/System.CommandLine.Tests/ParseErrorReportingTests.cs

@@ -7,7 +7,6 @@
 using System.CommandLine.Tests.Utility;
 using System.IO;
 using System.Linq;
-using System.Threading;
 using System.Threading.Tasks;
 using Xunit;
 

src/System.CommandLine.Tests/ParserTests.cs

@@ -15,12 +15,6 @@ namespace System.CommandLine.Tests
 {
     public partial class ParserTests
     {
-        private T GetValue<T>(ParseResult parseResult, Option<T> option)
-            => parseResult.GetValue(option);
-
-        private T GetValue<T>(ParseResult parseResult, Argument<T> argument)
-            => parseResult.GetValue(argument);
-
         [Fact]
         public void An_option_can_be_checked_by_object_instance()
         {
@@ -816,7 +810,7 @@ public void Commands_can_have_default_argument_values()
 
             ParseResult result = command.Parse("command");
 
-            GetValue(result, argument)
+            result.GetValue(argument)
                   .Should()
                   .Be("default");
 
@@ -861,7 +855,7 @@ public void When_an_option_with_a_default_value_is_not_matched_then_the_option_c
             ParseResult result = command.Parse("command");
 
             result.GetResult(option).Should().NotBeNull();
-            GetValue(result, option).Should().Be("the-default");
+            result.GetValue(option).Should().Be("the-default");
         }
 
         [Fact]
@@ -926,6 +920,48 @@ public void When_an_argument_with_a_default_value_is_not_matched_then_there_are_
                   .BeEmpty();
         }
 
+        [Fact]
+        public void When_an_argument_with_a_default_value_is_matched_then_the_option_result_is_implicit()
+        {
+            var argument = new Argument<string>("the-arg")
+            {
+                DefaultValueFactory = _ => "the-default"
+            };
+
+            var command = new Command("command")
+            {
+                argument
+            };
+
+            var result = command.Parse("command the-explicit-value");
+
+            result.GetResult(argument)
+                  .Implicit
+                  .Should()
+                  .BeFalse();
+        }
+
+        [Fact]
+        public void When_an_argument_with_a_default_value_is_not_matched_then_the_option_result_is_implicit()
+        {
+            var argument = new Argument<string>("the-arg")
+            {
+                DefaultValueFactory = _ => "the-default"
+            };
+
+            var command = new Command("command")
+            {
+                argument
+            };
+
+            var result = command.Parse("command");
+
+            result.GetResult(argument)
+                  .Implicit
+                  .Should()
+                  .BeTrue();
+        }
+
         [Fact]
         public void Command_default_argument_value_does_not_override_parsed_value()
         {
@@ -941,7 +977,7 @@ public void Command_default_argument_value_does_not_override_parsed_value()
 
             var result = command.Parse("the-directory");
 
-            GetValue(result, argument)
+            result.GetValue(argument)
                   .Name
                   .Should()
                   .Be("the-directory");
@@ -1125,7 +1161,7 @@ public void Option_arguments_can_start_with_prefixes_that_make_them_look_like_op
 
             var result = command.Parse(input);
 
-            GetValue(result, optionX).Should().Be("-y");
+            result.GetValue(optionX).Should().Be("-y");
         }
 
         [Fact]
@@ -1144,9 +1180,9 @@ public void Option_arguments_can_start_with_prefixes_that_make_them_look_like_bu
 
             var result = command.Parse("-a -bc");
 
-            GetValue(result, optionA).Should().Be("-bc");
-            GetValue(result, optionB).Should().BeFalse();
-            GetValue(result, optionC).Should().BeFalse();
+            result.GetValue(optionA).Should().Be("-bc");
+            result.GetValue(optionB).Should().BeFalse();
+            result.GetValue(optionC).Should().BeFalse();
         }
 
         [Fact]
@@ -1161,7 +1197,7 @@ public void Option_arguments_can_match_subcommands()
 
             var result = root.Parse("-a subcommand");
 
-            GetValue(result, optionA).Should().Be("subcommand");
+            result.GetValue(optionA).Should().Be("subcommand");
             result.CommandResult.Command.Should().BeSameAs(root);
         }
 
@@ -1182,7 +1218,7 @@ public void Arguments_can_match_subcommands()
 
             result.CommandResult.Command.Should().BeSameAs(subcommand);
 
-            GetValue(result, argument)
+            result.GetValue(argument)
                   .Should()
                   .BeEquivalentSequenceTo("one", "two", "three", "subcommand", "four");
 
@@ -1207,7 +1243,7 @@ public void Option_arguments_can_match_the_aliases_of_sibling_options_when_non_s
             var result = command.Parse(input);
 
             result.Errors.Should().BeEmpty();
-            GetValue(result, optionX).Should().Be("-y");
+            result.GetValue(optionX).Should().Be("-y");
         }
 
         [Fact]
@@ -1222,7 +1258,7 @@ public void Single_option_arguments_that_match_option_aliases_are_parsed_correct
 
             var result = command.Parse("-x -x");
 
-            GetValue(result, optionX).Should().Be("-x");
+            result.GetValue(optionX).Should().Be("-x");
         }
 
         [Theory]
@@ -1249,8 +1285,8 @@ public void Boolean_options_are_not_greedy(string commandLine)
 
             result.Errors.Should().BeEmpty();
 
-            GetValue(result, optX).Should().BeTrue();
-            GetValue(result, optY).Should().BeTrue();
+            result.GetValue(optX).Should().BeTrue();
+            result.GetValue(optY).Should().BeTrue();
         }
 
         [Fact]
@@ -1267,8 +1303,8 @@ public void Multiple_option_arguments_that_match_multiple_arity_option_aliases_a
 
             var result = command.Parse("-x -x -x -y -y -x -y -y -y -x -x -y");
 
-            GetValue(result, optionX).Should().BeEquivalentTo(new[] { "-x", "-y", "-y" });
-            GetValue(result, optionY).Should().BeEquivalentTo(new[] { "-x", "-y", "-x" });
+            result.GetValue(optionX).Should().BeEquivalentTo(new[] { "-x", "-y", "-y" });
+            result.GetValue(optionY).Should().BeEquivalentTo(new[] { "-x", "-y", "-x" });
         }
 
         [Fact]
@@ -1285,7 +1321,7 @@ public void Bundled_option_arguments_that_match_option_aliases_are_parsed_correc
 
             var result = command.Parse("-yxx");
 
-            GetValue(result, optionX).Should().Be("x");
+            result.GetValue(optionX).Should().Be("x");
         }
 
         [Fact]
@@ -1302,8 +1338,8 @@ public void Argument_name_is_not_matched_as_a_token()
 
             var result = command.Parse("name one two three");
 
-            GetValue(result, nameArg).Should().Be("name");
-            GetValue(result, columnsArg).Should().BeEquivalentTo("one", "two", "three");
+            result.GetValue(nameArg).Should().Be("name");
+            result.GetValue(columnsArg).Should().BeEquivalentTo("one", "two", "three");
         }
 
         [Fact]
@@ -1328,7 +1364,7 @@ public void Boolean_options_with_no_argument_specified_do_not_match_subsequent_a
 
             var result = command.Parse("-v an-argument");
 
-            GetValue(result, option).Should().BeTrue();
+            result.GetValue(option).Should().BeTrue();
         }
 
         [Fact]
@@ -1345,8 +1381,8 @@ public void When_a_command_line_has_unmatched_tokens_they_are_not_applied_to_sub
 
             var result = command.Parse("-x 23 unmatched-token -y 42");
 
-            GetValue(result, optionX).Should().Be("23");
-            GetValue(result, optionY).Should().Be("42");
+            result.GetValue(optionX).Should().Be("23");
+            result.GetValue(optionY).Should().Be("42");
             result.UnmatchedTokens.Should().BeEquivalentTo("unmatched-token");
         }
 
@@ -1648,7 +1684,7 @@ public void Parsed_value_of_empty_string_arg_is_an_empty_string(string arg1, str
 
             var result = rootCommand.Parse(new[] { arg1, arg2 });
 
-            GetValue(result, option).Should().BeEmpty();
+            result.GetValue(option).Should().BeEmpty();
         }
     }
 }