subcommand completions should include root command recursive options completions (#2209)

* add failing tests

* fix the bug: ParseResult.GetResult(rootCommand) should return root command parse result

* adjust existing tests to also include root command recursive options in completions

Author: adamsitnik

src/System.CommandLine.Tests/CompletionTests.cs

@@ -246,7 +246,28 @@ public void Command_GetCompletions_can_access_ParseResult()
                   .Should()
                   .BeEquivalentTo("test");
         }
-        
+
+        [Fact]
+        public void Command_GetCompletions_include_recursive_options_of_root_command()
+        {
+            CliRootCommand rootCommand = new()
+            {
+                new CliCommand("sub")
+                {
+                    new CliOption<int>("--option")
+                }
+            };
+
+            var result = rootCommand.Parse("sub --option 123 ");
+
+            _output.WriteLine(result.ToString());
+
+            result.GetCompletions()
+                  .Select(item => item.Label)
+                  .Should()
+                  .BeEquivalentTo("--help", "-?", "-h", "/?", "/h");
+        }
+
         [Fact]
         public void When_one_option_has_been_specified_then_it_and_its_siblings_will_still_be_suggested()
         {
@@ -414,7 +435,7 @@ public void When_a_subcommand_with_subcommands_has_been_specified_then_its_sibli
             result.GetCompletions(commandLine.Length + 1)
                   .Select(item => item.Label)
                   .Should()
-                  .BeEquivalentTo("rainier");
+                  .BeEquivalentTo("--help", "-?", "-h", "/?", "/h", "rainier");
         }
 
         [Fact]

src/System.CommandLine.Tests/ParseResultTests.cs

@@ -53,6 +53,23 @@ public void GetResult_can_be_used_to_check_the_presence_of_an_implicit_option()
             result.GetResult(option).Should().NotBeNull();
         }
 
+        [Fact]
+        public void GetResult_can_be_used_for_root_command_itself()
+        {
+            CliRootCommand rootCommand = new()
+            {
+                new CliCommand("the-command")
+                {
+                    new CliOption<int>("-c")
+                }
+            };
+
+            var result = rootCommand.Parse("the-command -c 123");
+
+            result.RootCommandResult.Command.Should().BeSameAs(rootCommand);
+            result.GetResult(rootCommand).Should().BeSameAs(result.RootCommandResult);
+        }
+
         [Fact]
         public void Command_will_not_accept_a_command_if_a_sibling_command_has_already_been_accepted()
         {

src/System.CommandLine.Tests/SuggestDirectiveTests.cs

@@ -79,9 +79,9 @@ public async Task It_writes_suggestions_for_option_arguments_when_under_root_com
         }
 
         [Theory]
-        [InlineData("[suggest:4] \"eat\"")]
-        [InlineData("[suggest:6] \"eat --\"")]
-        public async Task It_writes_suggestions_for_option_aliases_under_subcommand(string commandLine)
+        [InlineData("[suggest:4] \"eat\"", new[] { "--fruit", "--help", "--vegetable", "-?", "-h", "/?", "/h" })]
+        [InlineData("[suggest:6] \"eat --\"", new[] { "--fruit", "--help", "--vegetable" })]
+        public async Task It_writes_suggestions_for_option_aliases_under_subcommand(string commandLine, string[] expectedCompletions)
         {
             CliRootCommand rootCommand = new() { _eatCommand };
             CliConfiguration config = new(rootCommand)
@@ -94,10 +94,12 @@ public async Task It_writes_suggestions_for_option_aliases_under_subcommand(stri
 
             await result.InvokeAsync();
 
+            string expected = string.Join(NewLine, expectedCompletions) + NewLine;
+
             config.Output
                    .ToString()
                    .Should()
-                   .Be($"--fruit{NewLine}--vegetable{NewLine}");
+                   .Be(expected);
         }
 
         [Theory]

src/System.CommandLine/Parsing/ParseOperation.cs

@@ -36,6 +36,7 @@ public ParseOperation(
                 _configuration.RootCommand,
                 CurrentToken,
                 _symbolResultTree);
+            _symbolResultTree.Add(_configuration.RootCommand, _rootCommandResult);
 
             Advance();
         }