almaraubel / csharpfunctionalextensions.analyzers

Code analyzers for CSharpFunctionalExtensions

CSharpFunctionalExtensions.Analyzers

Unofficial code analyzers for CSharpFunctionalExtensions. This project aims to provide code analyzers to identify potential issues or misuse of the Result object from the CSharpFunctionalExtensions library.

Features

• Identifies scenarios where the IsSuccess property is not checked before accessing the Value.
• Verifies that logic is terminated when IsFailure is true before before accessing the Value.
• Supports a variety of control flow structures, including if statements, ternary operators, and now C# switch expressions.

Getting Started

To install the analyzers, you can add the NuGet package to your project:

Install-Package CSharpFunctionalExtensions.Analyzers

Examples

Here are some examples to show what this analyzer can catch.

Example 1: Accessing Value without checking IsSuccess

public void DoSomething(Result<int> result)
{
    var x = result.Value;  // Analyzer will report a warning here
}

Example 2: Using IsSuccess in Switch Expressions

public IActionResult ProcessResult(Result<int> result)
{
    return result switch
    {
        { Error: var err } when err == Error.NotFound => NotFound(),
        _ => Ok(result.Value)  // Analyzer will report a warning here
    };
}

Example 3: Not breaking out when IsFailure is true

public void DoSomething(Result<int> result)
{
    if (result.IsFailure)
    {
        // logic here
    }
    var x= result.Value; // Analyzer will report a warning here
}

Will be fixed if you return ;

public void DoSomething(Result<int> result)
{
   if (result.IsFailure)
   {
       return
   }
   var x= result.Value; // Analyzer will report a warning here
}

Changelog

See changelog

Contributing

Contributions are welcome! Please feel free to open an issue or submit a pull request.

License

MIT

csharpfunctionalextensions.analyzers's Issues

False postive warning of accessing value without checking with ternary operator

When you use the ternary operator like string resultMessage = result.IsSuccess ? $"{result.Value} success." : "Failed."; you get warning CFE0001 "Accessing Value without checking IsSuccess or IsFailure can result in an unexpected Errors". This is incorrect because the ternary operator is checking the value. Converting the ternary operator into a if else statement removes the warning.

Pattern matching

Checks on isSuccess with pattern matching are not recognized as correct check for isSuccess

 return result switch
        {
            { IsSuccess: true } => Ok(result.Value),
            { Error: var err } when err == Foo.Error.NotFound
                => NotFound(),
            _ => InternalServerError(result.Error.UserFriendlyName)
        };

False postive when value is used inside another if statement

var result = X();

if(result.IsFailure) return Error.NotFound;

if(a> 0)
{
    return result.Value // <-- still says this is unsafe access
}