Code Syntax Style: Null checking pattern

When checking an expression for null with the type-testing 'is' operator, you can choose between two null-checking patterns:

Use the 'not null' pattern that makes the expression more readable.
Use the object pattern syntax `{ }` that makes the expression more flexible, allowing you to declare a local variable after it.

                
public static void Test(object? obj)
{
  if (obj is not null)
    Console.WriteLine("not null");
}

            

                
public static void Test(object? obj)
{
  if (obj is { })
    Console.WriteLine("not null");
}

ReSharper helps you enforce style preferences for null-checking patterns in the existing code and takes your preferences into account when it produces new code with code completion and performs refactorings.

Enforce preferences for null-checking patterns

By default, ReSharper highlights object pattern syntax { } in null-checking expressions and suggests replace them with the not null pattern:

ReSharper syntax style inspection: Use 'not null' pattern

If you prefer to use the { } pattern, you can change the corresponding preferences and ReSharper will help you replace not null patterns accordingly:

ReSharper syntax style inspection: Use '{ }' pattern

Configure preferences for null-checking patterns

You can configure syntax style settings via EditorConfig. These settings can be stored in .editorconfig files on different levels of your solution hierarchy. The files are normally put under VCS so that settings defined there are shared among the project team.

If you have used ReSharper for Visual Studio or JetBrains Rider on your computer, or have opened the current solution using these tools, ReSharper for Visual Studio Code will read and apply your syntax style settings from .DotSettings files. However, any settings configured via .editorconfig will take precedence.

Configure preferences for null-checking pattern using EditorConfig

Open the desired .editorconfig file.
Add the required null-checking pattern properties to the file. For example:
null_checking_pattern_style = empty_recursive_pattern

03 March 2026