What is the best way to check the parameters of the method? [closed]

Answer 1

Updated July 2020

Check out this blog post on how you can achieve a similar approach to Code Contracts.

https://enterprisecraftsmanship.com/posts/code-contracts-vs-input-validation/

Original answer provided below

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If you are using .NET framework 4, check out Code Contracts, which simplifies it down to a single line of code

public string Reverse(string text)
{
   Contract.Requires<ArgumentNullException>(text!=null, "ParAmeter cannot be null.");
  
   .....
}

The reason you would use this is because you can now get automated tools like Pex to tell you what unit tests to apply to this method. It also gives you feedback at compile time if this method would throw an exception based on how you are calling it. Like

String text = null;
String reversedString = Reverse(text);

The compiler will warn you that this will throw an exception.

Note Code Contracts needs an add-in to be installed, but it is free.