Any .NET Fluent Argument checking libraries out there?

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 :)

Try FluentValidation

Or FluentValidation for .NET 2.0