Cake Frosting Parent DirectoryPath Fails To Combine with Slash

[lprichar]

Prerequisites

• I have written a descriptive issue title
• I have searched issues to ensure it has not already been reported

Cake runner

Cake Frosting

Cake version

1.1.0

Operating system

Linux, Windows

Operating system architecture

64-Bit

CI Server

No response

What are you seeing?

A NullReferenceException in the code sample below. However, that's more the symptom than the cause. The problem appears to be that Cake Frosting is combining Directory("..") + Directory("temp") into "..temp" rather than "../temp" when you capture the context and then use expression bodied properties.

This may seem obscure, but I'm converting a large codebase of DSL Cake into Frosting and am looking for ways to accomplish it with minimal changes.

What is expected?

It should run to completion without an exception

Steps to Reproduce

Run this:

[TaskName("Fail")]
public class FailTask : FrostingTask<BuildContext>
{
    private BuildContext? _context;
    private DirectoryPath RootDir => _context.Directory("..");
    private DirectoryPath TestDir => RootDir + _context.Directory("temp");

    public override void Run(BuildContext context)
    {
        _context = context;
        context.GetFiles(TestDir + context.File("*.zip"));
    }
}

Output log

Error: System.NullReferenceException: Object reference not set to an instance of an object.
   at Cake.Core.IO.Globbing.GlobVisitor.VisitParent(ParentDirectoryNode node, GlobVisitorContext context)
   at Cake.Core.IO.Globbing.Nodes.ParentDirectoryNode.Accept(GlobVisitor visitor, GlobVisitorContext context)
   at Cake.Core.IO.Globbing.GlobVisitor.VisitRelativeRoot(RelativeRootNode node, GlobVisitorContext context)
   at Cake.Core.IO.Globbing.Nodes.RelativeRootNode.Accept(GlobVisitor globber, GlobVisitorContext context)
   at Cake.Core.IO.Globbing.GlobVisitor.Walk(GlobNode node, GlobberSettings settings)
   at Cake.Core.IO.Globber.Match(GlobPattern pattern, GlobberSettings settings)
   at Cake.Core.IO.GlobberExtensions.Match(IGlobber globber, GlobPattern pattern)
   at Cake.Common.IO.GlobbingAliases.GetFiles(ICakeContext context, GlobPattern pattern)
   ...

[patriksvensson]

GetFiles takes a string so it will implicitly convert the content to a string. Try using TestDir.CombineWithFilePath(..) and you should get the correct result.

[lprichar]

Didn't help, I'm afraid. More specifically:

[TaskName("Fail")]
public class FailTask : FrostingTask<BuildContext>
{
    private BuildContext? _context;
    private DirectoryPath RootDir => _context.Directory("..");
    private DirectoryPath TestDir => RootDir + _context.Directory("temp");

    public override void Run(BuildContext context)
    {
        _context = context;
        var filePath = TestDir.CombineWithFilePath(context.File("*.zip"));
        _context.Information(filePath);
    }
}

returns ..temp/*.zip. That's really the source of the problem.

I'd be inclined to argue that a null reference exception from GetFiles is never the correct response, but again that's just more a symptom of the underlying problem which is the way directories are being combined is incorrect in this context.

[lprichar]

Found a workaround. If you replace:

private DirectoryPath TestDir => RootDir + _context.Directory("temp");

with

private DirectoryPath TestDir => RootDir.Combine(_context.Directory("temp"));

then it works. Strange bug, I can't even begin to understand how that syntax change could make a difference. Just to make this easily reproduceable:

[TaskName("Fail")]
public class FailTask : FrostingTask<BuildContext>
{
    private BuildContext? _context;
    private DirectoryPath RootDir => _context.Directory("..");
    private DirectoryPath TestDir1 => RootDir + _context.Directory("temp");
    private DirectoryPath TestDir2 => RootDir.Combine(_context.Directory("temp"));

    public override void Run(BuildContext context)
    {
        _context = context;
        _context.Information(TestDir1);
        _context.Information(TestDir2);
    }
}

returns:

..temp
../temp

but should return:

../temp
../temp

[augustoproiete]

@lprichar We're missing a + operator that takes a DirectoryPath and ConvertableDirectoryPath, and ConvertableDirectoryPath has an implicit operator that casts it string so C# is effectively concatenating two strings in your case, rather than combining the file paths.

Fixed via PR #3353

[lprichar]

Oh, of course! That makes sense. Thanks @augustoproiete, looking forward to the next release.

[augustoproiete]

@lprichar Thanks for reporting! Nice find!