System.CommandLine CLI parsing library won't call a method on a mocked object

[bradykelly]

System.CommandLine is a package from MS for parsing command-line arguments. It fails to do this properly when asked to invoke a method on a mocked object.

With the following code in ApplicationService:

public async Task<int> RunAsync(string[] cliArgs)
{
    var rootCommand = BuildCommandTree();

    rootCommand.Handler = CommandHandler.Create(delegate (string table, string? model, string? schema, bool overwrite, IConsole console)
    {
        _builderService.BuildForSingleTable(table, model, schema, overwrite);
    });
    //var returnCode = await rootCommand.InvokeAsync(cliArgs);
    var returnCode = await rootCommand.InvokeAsync(cliArgs);
    return returnCode;
}

and this mocking code:

    _builderMock.Setup(x => x.BuildForSingleTable(
        It.Is<string>(s => s.Equals(tableName)), 
        It.Is<string>(s => s.Equals(modelName)), 
        It.Is<string>(s => s.Equals(schemaName)), 
        It.Is<bool>(x => x))).Verifiable();
        
var tempSut = new ApplicationService(_loggerMock.Object, _configMock.Object, _builderMock.Object);
await tempSut.RunAsync(args);        

where _builderService and _builderMock are both IBuilderService, but RunAsync only works when _builderService is a real BuilderService and not a mock.

When _builderService is a mock BuildForSingleTable is never called and InvokeAsync returns 1, indicating an error I presume, but when _builderService is a concrete BuilderService, InvokeAsync returns 0 and my method is called.

I thought I'd open an issue because here Moq is failing in what it's supposed to do: appear to a method as a normal object. I have also reported this on the System.CommandLine repo. I am using Moq

[stakx]

It's a bit tedious having to piece together a repro from prose. Please post a minimal but complete code repro, otherwise there's nothing we can do to help.

[bradykelly]

I have since found out that using a stub with a string[] array passed as args has the same effect. I may have something wrong with my args setup so I will close this and wait and see before I open another one. Sorry about that.