SubSpec allows developers to write declarative tests operating at all layers of abstraction consisting of highly composable, small primitive concepts. Based on the powerful xUnit testing framework, SubSpec is easy to integrate with existing testing environments.
Midje is a test framework for Clojure. I created it to support top-down as well as bottom-up testing, to encourage readable tests, to provide a smooth migration path from clojure.test and to support a balance between abstraction and concreteness.
CxxTest is a unit testing framework for C++ that is similar in spirit to JUnit, CppUnit, and xUnit. CxxTest is easy to use because it does not require precompiling a CxxTest testing library, it employs no advanced features of C++ (e.g. RTTI) and it supports a very flexible form of test discovery.
NSubstitute is a friendly substitute for .NET mocking frameworks. NSubstitute is designed for Arrange-Act-Assert (AAA) testing, so you just need to arrange how it should work, then assert it received the calls you expected once you're done. Because you've got more important code to write than whether you need a mock or a stub.
SilverUnit allows true unit testing in Silverlight. SilverUnit is the first framework that introduces the concept of Crosswise-Isolation: Isolation concepts can be performed for all objects and calls in the system.