DeltaEngine.Extensions NamespaceDelta Engine Documentation
Also part of the common Delta.Utilities assembly. This namespace contains several helper classes, which mostly extend existing .NET functionality for strings, enums, files, dates, directories, math, threads, etc.

An example can be found here:

Public classArrayExtensions
Additional array manipulation and array to text methods. View code on GitHub
Public classAssemblyExtensions
Additional methods for assembly related actions. View code on GitHub
Public classAssemblyStarter
Used to start VisualTests from assemblies in an extra AppDomain for the SampleBrowser. Also used in the ContinuousUpdater to get all tests and start them safely in the Editor. View code on GitHub
Public classChangeableList T 
Like , but allows you to add and remove elements while enumerating. When all enumerations are complete, all remembered removed and added elements will be applied. Use when adding and removing is rare, otherwise just create a new list before enumerating. List T View code on GitHub
Public classDateExtensions
Allows to write out date values as structured iso date strings and parses iso or english dates View code on GitHub
Public classEnumExtensions
Provides the number of elements in an enum and some conversion and enumeration methods. View code on GitHub
Public classExceptionExtensions
Categorizes exceptions into fatal and weak ones. Fatal exceptions are always rethrown and weak ones (most likely simple programming mistakes) can be logged and ignored if no debugger is attached. See View code on GitHub
Public classMathExtensions
Extends the System.Math class, but uses floats and provides some extra constants. View code on GitHub
Public classPathExtensions
Public classPathExtensions NoDeltaEngineFoundInFallbackPaths
Public classStackTraceExtensions
Provides additional check methods on stack traces to find out where we are (e.g. in tests) View code on GitHub
Public classStringExtensions
Provides additional and simplified string manipulation methods. View code on GitHub
Public classThreadExtensions
Useful wrapper functions for threading. View code on GitHub
Public classThreadStatic T 
Provides an object which can be scoped and is static within a thread (e.g. tests). Based on View code on GitHub
Public classThreadStatic T  DisposingOnDifferentThreadToCreation
Public classThreadStatic T  NoValueAvailable
Public classUniqueList T