Another one of those pesky guard clause libraries. Krav means requirement in Swedish.
You can install Krav through nuget
Install-Package Krav
Using the library is as simple as this
Require.That(foo, "foo").IsNotNull();
Require.That(bar, "bar").IsANumber();
Require.That(baz, "baz").GreaterThan(1).LessThan(4);
You can also use lambda expressions for that lovely refactor-safe feeling. Keep in mind that this method is costlier in performance. You can run the provided performance tests to find out just how much costlier. But for anything that isn't library code this should probably be the technique of choice.
Require.That(() => foo).IsNotNull();
Require.That(() => bar).IsANumber();
Require.That(() => baz).GreaterThan(1).LessThan(4);
And if you were that worried about performance you would be using Krav.Simple instead.
Yes. If performance is more important than fancyness and readability in the project you're working on this is the one for you. It's really just a collection of static methods and predefined exception messages.
Install it via NuGet
Install-Package Krav.Simple
And use it like this
RequireThat.NotNull(foo, "foo");
RequireThat.NotNullOrWhitespace(bar, "bar");
If a requirement method is not available for something you need you can always use the Require.That(statement, message) method.
Require.That(foo != "bar", "foo was bar");
This will throw an ArgumentException with the provided message if the statement evaluates to false.
If there's a good case to be made for including the requirement that you need, you might also create an issue and/or pull request to have it included.
There's a Krav.PerformanceTests project that runs a number of iterations using each technique and displays the results.
Non-lambda test results
-----------------------
Total time: 0.12 ms (404 ticks)
Average time: 0.01 ms (20.2 ticks)
Range: 0.01 - 0.01 ms (19 - 29 ticks)
Lambda test results
-------------------
Total time: 0.21 ms (713 ticks)
Average time: 0.01 ms (35.65 ticks)
Range: 0.01 - 0.10 ms (20 - 316 ticks)
Simple test results
-------------------
Total time: 0.00 ms (12 ticks)
Average time: 0.00 ms (0.6 ticks)
Range: 0.00 - 0.00 ms (0 - 1 ticks)
But I would take this thing with a grain of salt. As you can see the range on Lambda tests is completely wonky.