dotnet format --verify-no-changes: format C# code and check it in CI

dotnet format rewrites the C# (and Visual Basic) files of a project or solution to follow the rules in .editorconfig: whitespace and indentation, code style preferences and fixable analyzer warnings. Add --verify-no-changes to change nothing and exit with code 2 when a file is not formatted, which is the check to run in CI. dotnet format whitespace runs only the fast whitespace pass.

Check, fix, check again

dotnet new console -o App > /dev/null
cd App
printf 'class Program\n{\nstatic void Main()  {   System.Console.WriteLine("hi");}\n}\n' > Program.cs
dotnet format whitespace --verify-no-changes > /dev/null 2>&1
echo "verify exit code: $?"
dotnet format whitespace
dotnet format whitespace --verify-no-changes
echo "verify exit code: $?"
cat Program.cs

verify exit code: 2
verify exit code: 0
class Program
{
    static void Main() { System.Console.WriteLine("hi"); }
}

The badly indented file made --verify-no-changes fail with exit code 2; its messages name each file and line, such as Fix whitespace formatting. After dotnet format whitespace rewrote the file, the same check passed with exit code 0.

Subcommands and options

Pitfalls

• Exit codes. 0 means nothing to change (or everything fixed) and 2 means --verify-no-changes found files to format; other failures, such as a project that does not load, also exit non-zero. A CI script should treat any non-zero code as a failure.
• Several projects in one folder. Like other dotnet commands, dotnet format without a path fails with MSB1011; pass the solution or project file.
• Style and analyzer passes need a restore. Without restored packages they cannot load the project; run dotnet restore first, or use --no-restore only when CI already restored.
• Line endings. On Windows with Git's core.autocrlf, files can switch between CRLF and LF and appear unformatted. Set end_of_line in .editorconfig and a matching .gitattributes.

How to confirm it worked

dotnet format --verify-no-changes exiting with 0 confirms that every file follows the rules; run it in the same CI job as the build. git diff after dotnet format shows exactly what it changed. JavaScript projects have the same check pattern with deno fmt --check or Prettier.

FAQ