houfeng / exposedobject

ExposedObject

Fast dynamic wrapper for accessing hidden methods and fields of .Net objects. Uses 4.0 dynamic feature to allow seamless access to non-public object members. Facilitates white-box unit testing, exposes APIs that should be public and allows construction of elaborate hacks. Should not kill your cat provided you are careful. Available on NuGet.

Usage examples

Handling private instance methods, fields and properties on a visible type:

// create an Exposed instance from a ClassWithHiddenMethods instance
dynamic exposed = Exposed.From(new ClassWithHiddenMethods());
// calling a private method
string password = exposed.GeneratePassword(8);
// reading a private field
int privateFieldValue = exposed.internalCount;
// setting a private field
exposed.internalCount = privateFieldValue * 2;
// reading a protected property
char protectedPropertyValue = exposed.InternalData;

Accessing private field on a hidden type:

// get the Type via reflection
Type hiddenClass = Type.GetType("TestSubjects.HiddenClass, TestSubjects");
// call the parameterless constructor of a hidden type
dynamic exposed = Exposed.New(hiddenClass);
string password = exposed.password;

Accessing internal static method from type:

dynamic exposed = Exposed.From(typeof(ClassWithInternalStaticMethod));
decimal convertValue = exposed.ConvertValue(8);

TODO:

• performance assessment (binding restrictions vs caching, compare with CreateDelegate solution)
• generic methods (there are tests for them, some suggested solutions on StackOverflow )
• constructors (currently Exposed.New() delegates to Activator.CreateInstance() )

Ideas borrowed from:

• Bug squash: Testing private methods with C# 4.0 - starting idea
• Igor Ostrovsky: Use C# dynamic typing to conveniently access internals of an object - convenient API
• Miguel de Icaza: C# 4's Dynamic in Mono - performant dynamic object implementation using GetMetaObject()