Using the ruleset file and Rule Set editor to configure analyzers

In this recipe, we will show you how to use the ruleset file and the Rule Set editor in Visual Studio to configure the per-project severity of analyzer rules, and illustrate how the severity changes are reflected in the live diagnostics in Visual Studio, as well as command-line builds.

Getting ready

You will need to have created and opened a .NET project in Visual Studio 2017 with NuGet-based analyzers installed in the project. Refer to the first recipe in this chapter for installing analyzers in a .NET project.

How to do it...

1. Open a C# project, say ClassLibrary, with the analyzer NuGet package System.Runtime.Analyzers.nupkg prerelease version 1.2.0-beta2 installed in it.
2. Add the following source code to the project and verify that no CA1813: Avoid unsealed attributes is fired:

using System;

namespace ClassLibrary
{
  [AttributeUsage(AttributeTargets.All)]
  public class MyAttribute: Attribute
  {
  }
}

3. In the solution explorer...