[release/8.0.4xx] Add tab completion for 'dotnet nuget why' command (#41448)

Co-authored-by: Advay Tandon <[email protected]>

Author: github-actions[bot]

src/Cli/dotnet/commands/dotnet-nuget/NuGetCommandParser.cs

@@ -35,6 +35,7 @@ private static CliCommand ConstructCommand()
             command.Subcommands.Add(GetVerifyCommand());
             command.Subcommands.Add(GetTrustCommand());
             command.Subcommands.Add(GetSignCommand());
+            command.Subcommands.Add(GetWhyCommand());
 
             command.SetAction(NuGetCommand.Run);
 
@@ -213,5 +214,19 @@ private static CliCommand GetSignCommand()
 
             return signCommand;
         }
+
+        private static CliCommand GetWhyCommand()
+        {
+            CliCommand whyCommand = new("why");
+
+            whyCommand.Arguments.Add(new CliArgument<string>("PROJECT|SOLUTION") { Arity = ArgumentArity.ExactlyOne });
+            whyCommand.Arguments.Add(new CliArgument<string>("PACKAGE") { Arity = ArgumentArity.ExactlyOne });
+
+            whyCommand.Options.Add(new CliOption<string>("--framework", "-f") { Arity = ArgumentArity.ZeroOrMore });
+
+            whyCommand.SetAction(NuGetCommand.Run);
+
+            return whyCommand;
+        }
     }
 }

src/Tests/dotnet-nuget.UnitTests/GivenANuGetCommand.cs

@@ -75,6 +75,9 @@ public GivenANuGetCommand(ITestOutputHelper log) : base(log)
                                    "--interactive",
                                    "--verbosity", "detailed",
                                    "--format", "json"}, 0)]
+        [InlineData(new[] { "why" }, 0)]
+        [InlineData(new[] { "why", "C:\\path", "Fake.Package" }, 0)]
+        [InlineData(new[] { "why", "C:\\path", "Fake.Package", "--framework", "net472", "-f", "netcoreapp5.0" }, 0)]
 
         public void ItPassesCommandIfSupported(string[] inputArgs, int result)
         {

src/Tests/dotnet.Tests/CommandTests/CompleteCommandTests.cs

@@ -118,7 +118,8 @@ public void GivenNuGetCommandItDisplaysCompletions()
                 "push",
                 "verify",
                 "trust",
-                "sign"
+                "sign",
+                "why"
             };
 
             var reporter = new BufferedReporter();
@@ -286,6 +287,24 @@ public void GivenNuGetSignCommandItDisplaysCompletions()
             reporter.Lines.OrderBy(c => c).Should().Equal(expected.OrderBy(c => c));
         }
 
+        [Fact]
+        public void GivenNuGetWhyCommandItDisplaysCompletions()
+        {
+            var expected = new[] {
+                "--framework",
+                "--help",
+                "-?",
+                "-f",
+                "-h",
+                "/?",
+                "/h"
+            };
+
+            var reporter = new BufferedReporter();
+            CompleteCommand.RunWithReporter(new[] { "dotnet nuget why " }, reporter).Should().Be(0);
+            reporter.Lines.OrderBy(c => c).Should().Equal(expected.OrderBy(c => c));
+        }
+
         [Fact]
         public void GivenDotnetAddPackWithPosition()
         {