HelpSubsystemTests.cs

// 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 FluentAssertions;
using Xunit;
using System.CommandLine.Parsing;

namespace System.CommandLine.Subsystems.Tests;

public class HelpSubsystemTests
{
    [Fact]
    public void When_help_subsystem_is_used_the_help_option_is_added_to_each_command_in_the_tree()
    {
        var rootCommand = new CliRootCommand
            {
                new CliOption<bool>("-x"), // add option that is expected for the test data used here
                new CliCommand("a")
            };
        var configuration = new CliConfiguration(rootCommand);

        var pipeline = Pipeline.CreateEmpty();
        pipeline.Help = new HelpSubsystem();

        // Parse is used because directly calling Initialize would be unusual
        var result = pipeline.Parse(configuration, "");

        rootCommand.Options
            .Count(x => x.Name == "--help")
            .Should()
            .Be(1);
        var subcommand = rootCommand.Subcommands.First();
        subcommand.Options
            .Count(x => x.Name == "--help")
            .Should()
            .Be(1);
    }

    [Theory]
    [ClassData(typeof(TestData.Help))]
    public void Help_is_activated_only_when_requested(string input, bool result)
    {
        CliRootCommand rootCommand = [new CliOption<bool>("-x")]; // add random option as empty CLIs are rare
        var configuration = new CliConfiguration(rootCommand);
        var helpSubsystem = new HelpSubsystem();
        var args = CliParser.SplitCommandLine(input).ToList().AsReadOnly();

        Subsystem.Initialize(helpSubsystem, configuration, args);

        var parseResult = CliParser.Parse(rootCommand, input, configuration);
        var isActive = Subsystem.GetIsActivated(helpSubsystem, parseResult);

        isActive.Should().Be(result);
    }

    [Fact]
    public void Outputs_help_message()
    {
        var consoleHack = new ConsoleHack().RedirectToBuffer(true);
        var helpSubsystem = new HelpSubsystem();
        Subsystem.Execute(helpSubsystem, new PipelineResult(null, "", null, consoleHack));
        consoleHack.GetBuffer().Trim().Should().Be("Help me!");
    }

    [Fact]
    public void Custom_help_subsystem_can_be_used()
    {
        var consoleHack = new ConsoleHack().RedirectToBuffer(true);
        var pipeline = Pipeline.CreateEmpty();
        pipeline.Help = new AlternateSubsystems.AlternateHelp();

        pipeline.Execute(new CliConfiguration(new CliRootCommand()), "-h", consoleHack);
        consoleHack.GetBuffer().Trim().Should().Be("***Help me!***");
    }
}