This is a legacy project, however, we have made some changes to it for the Post Build Signing epic so we should have tests added to cover these changes (per this PR https://github.com/dotnet/arcade/pull/5210/files).

• Create a unit test project for SignCheck in Arcade
• GetInputFilesFromOptions function in SignCheck.cs (as this is currently a private method, we may need to use Reflection or the PrivateObject functionality for testing)
• Unit tests for the entire SignCheckTask class