Any .NET Fluent Argument checking libraries out there?

Question

while looking at Shrinkr's source code (we all review other project's source code to learn, right??? :) ) I noticed the following kewl code .. (abbreviated by me, below)

public virtual Foo Foo
{
    get;
    set 
    {
        Check.Argument.IsNotNull(value, "value"); 
        // then do something.
    }
}

Notice the fluent way they check for arguments? Nice :)

_{(source: cherrythian.com)}

So .. checking the code, they have some custom class that does this...

public static class Check
{
    public static class Argument
    {
        public static void IsNotNull(object parameter, 
                                     string parameterName)
        { ... }

        public static void IsNotNullOrEmpty(string parameter, 
                                            string parameterName)
        { ... }

 .... etc ....
}

Are there any common frameworks out there?

gem install netFluentCheck ?

:)

Answer 1

I ended up using CuttingEdge Conditions, found on Codeplex.

eg.

// Check all preconditions:
Condition.Requires(id, "id")
    .IsNotNull()          // throws ArgumentNullException on failure
    .IsInRange(1, 999)    // ArgumentOutOfRangeException on failure
    .IsNotEqualTo(128);   // throws ArgumentException on failure

nice :)

Answer 2

You can try Bytes2you.Validation (Project). It is fast, extensible, intuitive and easy-to-use C# library providing fluent APIs for argument validation. Gives everything you need to implement defensive programming in your .NET application.

Answer 3

Try FluentValidation

Or FluentValidation for .NET 2.0

Answer 4

Here's one that uses Expressions. Since it's pretty trivial, everyone seems to have their own implementation of this...

Answer 5

Here's a simple class only a few lines long that I wrote a while ago ( from here : http://code.google.com/p/hotwire-queue/wiki/QuickAssert) that does something similar to fluent validation, uses a slightly different style that I find a bit easier to read (ymmv). Doesn't require any third party libraries, and if the validation fails, you get a simple error message with the exact code that failed.

config.Active.Should().BeTrue();
config.RootServiceName.Should().Be("test-animals");
config.MethodValidation.Should().Be(MethodValidation.afterUriValidation);
var endpoints = config.Endpoints;
endpoints.Should().NotBeNull().And.HaveCount(2);

to this:

config.Ensure(c => c.Active,
              c => c.RootServiceName == "test-animals",
              c => c.MethodValidation == MethodValidation.afterUriValidation,
              c => c.Endpoints != null && c.Endpoints.Count() == 2);

Here's the class, hope it's helpful as a starting point for someone ;-D

using System;
using System.Linq.Expressions;
using NUnit.Framework;

namespace Icodeon.Hotwire.Tests.Framework
{
    public static class QuickAssert
    {
        public static void Ensure<TSource>(this TSource source, params Expression<Func<TSource, bool>>[] actions)
        {
            foreach (var expression in actions)
            {
                Ensure(source,expression);
            }
        }

        public static void Ensure<TSource>(this TSource source, Expression<Func<TSource, bool>> action)
        {
            var propertyCaller = action.Compile();
            bool result = propertyCaller(source);
            if (result) return;
            Assert.Fail("Property check failed -> " + action.ToString());
        }
    }
}

At the time I wrote Ensure, code contracts were not supported in Visual studio 2010, but are now, see http://msdn.microsoft.com/en-us/magazine/hh148151.aspx