Command-line-api: Bug: Second string argument gets first string argument's value

[urig]

Hello,

DragonFruit looks sweet and I look forward to using it someday. Thank you!

I think I'm seeing a bug in System.CommandLine,DragonFruit. Full details below. Please let me know if I can help with finding and fixing.

Environment:

OS: Windows 10 Professional
.Net Core: 3.1.201
IDE: Visual Studio 2019 v16.5.3
System.CommandLine,DragonFruit: 0.3.0-alpha.20213.1

Reproduction:

https://github.com/urig/dragonfruit-repro

Steps to reproduce:

1. In Visual Studio 2019, create a new .Net Core Console Application project.

2. Add a NuGet dependency on DargonFruit:
   <PackageReference Include="System.CommandLine.DragonFruit" Version="0.3.0-alpha.20213.1" />

3. Change the Main() to accept two string arguments and print them:

   static void Main(string foo, string bar)
   {
       Console.WriteLine($"foo is {foo}");
       Console.WriteLine($"bar is {bar}");
   }
   

4. Build and run the Console Application with the foo argument:
   ConsoleApplication1.exe --foo foo

Expected behavior:

string foo should be set to 'foo' and string bar should be set to null, printing:

foo is foo
bar is

Actual behavior

string foo is set to 'foo' and string bar is also set to 'foo', printing:

foo is foo
bar is foo

[HGSandhagen]

Same behaviour also with
rootCommand.Handler = CommandHandler.Create<string, string>(Export);

It seems, that the types are checked only.

[Keboo]

Fixed by #853

[jonsequitur]

This appears to be the same issue as #854. Please try the latest release from nuget.org and let us know if you're still seeing the issue.

[urig]

I tried writing a unit test that would detect the actual behavior, in (CommandLineTests.cs):

    [Fact]
    public async Task It_executes_method_with_two_strings()
    {
        int exitCode = await CommandLine.InvokeMethodAsync(
            new[] { "--first", "Bruce" },
            TestProgram.TestMainWithTwoStringsMethodInfo,
            null,
            _testProgram,
            _terminal);
        exitCode.Should().Be(0);
        // expected actual value to be "Bruce Bruce", but it isn't and this passes:
        _terminal.Out.ToString().Should().Be("Bruce ");
    }

But the behavior is not reproduced when I run it. What am I missing?

[jonsequitur]

Which version are you using?

[urig]

I can confirm this is fixed for me in 0.3.0-alpha.20214.1. Joy 😀

Thank you @jonsequitur @Keboo 🙏🏻