Localizing required option not provided message

There is a slight behavior change for options that have multiple aliases as it will select the longest alias. This is to make it more consistent with how the Name property on the option works.

Author: Keboo

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

@@ -188,6 +188,7 @@ System.CommandLine
     public System.String NoArgumentProvided(System.CommandLine.Parsing.SymbolResult symbolResult)
     public System.String RequiredArgumentMissing(System.CommandLine.Parsing.SymbolResult symbolResult)
     public System.String RequiredCommandWasNotProvided()
+    public System.String RequiredOptionWasNotProvided(Option option)
     public System.String ResponseFileNotFound(System.String filePath)
     public System.String SuggestionsTokenNotMatched(System.String token)
     public System.String UnrecognizedArgument(System.String unrecognizedArg, System.Collections.Generic.IReadOnlyCollection<System.String> allowedValues)

src/System.CommandLine.Tests/GlobalOptionTests.cs

@@ -43,7 +43,25 @@ public void When_a_required_global_option_is_omitted_it_results_in_an_error()
                   .ContainSingle()
                   .Which.Message.Should().Be("Option '--i-must-be-set' is required.");
         }
-        
+
+        [Fact] 
+        public void When_a_required_global_option_has_multiple_aliases_the_error_message_uses_longest()
+        {
+            var rootCommand = new RootCommand();
+            var requiredOption = new Option<bool>(new[] { "-i", "--i-must-be-set" })
+            {
+                IsRequired = true
+            };
+            rootCommand.AddGlobalOption(requiredOption);
+
+            var result = rootCommand.Parse("");
+
+            result.Errors
+                  .Should()
+                  .ContainSingle()
+                  .Which.Message.Should().Be("Option '--i-must-be-set' is required.");
+        }
+
         [Fact]
         public void When_a_required_global_option_is_present_on_child_of_command_it_was_added_to_it_does_not_result_in_an_error()
         {

src/System.CommandLine.Tests/ParsingValidationTests.cs

@@ -177,6 +177,30 @@ public void When_a_required_option_is_not_supplied_then_an_error_is_returned()
                   .Be("Option '-x' is required.");
         }
 
+        [Fact]
+        public void When_a_required_option_has_multiple_aliases_the_error_message_uses_longest()
+        {
+            var command = new Command("command")
+            {
+                new Option<string>(new[] {"-x", "--xray" })
+                {
+                    IsRequired = true
+                }
+            };
+
+            var result = command.Parse("");
+
+            result.Errors
+                  .Should()
+                  .HaveCount(1)
+                  .And
+                  .Contain(e => e.SymbolResult.Symbol == command)
+                  .Which
+                  .Message
+                  .Should()
+                  .Be("Option '--xray' is required.");
+        }
+
         [Theory]
         [InlineData("subcommand -x arg")]
         [InlineData("-x arg subcommand")]

src/System.CommandLine/LocalizationResources.cs

@@ -98,6 +98,12 @@ symbolResult is CommandResult
         public virtual string RequiredCommandWasNotProvided() =>
             GetResourceString(Properties.Resources.RequiredCommandWasNotProvided);
 
+        /// <summary>
+        ///   Interpolates values into a localized string similar to Option '{0}' is required.
+        /// </summary>
+        public virtual string RequiredOptionWasNotProvided(Option option) =>
+            GetResourceString(Properties.Resources.RequiredOptionWasNotProvided, option.Aliases.OrderByDescending(x => x.Length).First());
+
         /// <summary>
         ///   Interpolates values into a localized string similar to Argument &apos;{0}&apos; not recognized. Must be one of:{1}.
         /// </summary>

src/System.CommandLine/Parsing/ParseResultVisitor.cs

@@ -360,8 +360,9 @@ private void ValidateCommandResult()
                         {
                             AddErrorToResult(
                                 _innermostCommandResult,
-                                new ParseError($"Option '{option.Aliases.First()}' is required.",
-                                               _innermostCommandResult));
+                                new ParseError(
+                                    _rootCommandResult.LocalizationResources.RequiredOptionWasNotProvided(option),
+                                    _innermostCommandResult));
                         }
                     }
                 }

src/System.CommandLine/Properties/Resources.Designer.cs

@@ -231,4 +231,7 @@
   <data name="ArgumentConversionCannotParseForOption" xml:space="preserve">
     <value>Cannot parse argument '{0}' for option '{1}' as expected type '{2}'.</value>
   </data>
+  <data name="RequiredOptionWasNotProvided" xml:space="preserve">
+    <value>Option '{0}' is required.</value>
+  </data>
 </root>

src/System.CommandLine/Properties/Resources.resx

@@ -162,6 +162,11 @@
         <target state="new">Required command was not provided.</target>
         <note />
       </trans-unit>
+      <trans-unit id="RequiredOptionWasNotProvided">
+        <source>Option '{0}' is required.</source>
+        <target state="new">Option '{0}' is required.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="ResponseFileNotFound">
         <source>Response file not found '{0}'.</source>
         <target state="new">Response file not found '{0}'.</target>

src/System.CommandLine/Properties/xlf/Resources.cs.xlf

@@ -162,6 +162,11 @@
         <target state="new">Required command was not provided.</target>
         <note />
       </trans-unit>
+      <trans-unit id="RequiredOptionWasNotProvided">
+        <source>Option '{0}' is required.</source>
+        <target state="new">Option '{0}' is required.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="ResponseFileNotFound">
         <source>Response file not found '{0}'.</source>
         <target state="new">Response file not found '{0}'.</target>

src/System.CommandLine/Properties/xlf/Resources.de.xlf

@@ -162,6 +162,11 @@
         <target state="new">Required command was not provided.</target>
         <note />
       </trans-unit>
+      <trans-unit id="RequiredOptionWasNotProvided">
+        <source>Option '{0}' is required.</source>
+        <target state="new">Option '{0}' is required.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="ResponseFileNotFound">
         <source>Response file not found '{0}'.</source>
         <target state="new">Response file not found '{0}'.</target>