A development environment in which unit tests are prepared. The unit tests run in a host environment for more complete and accurate testing of program units. The development environment uses a test execution shim to access an adapter running in the host environment. The host adapter may invoke other program objects that run specific tests. Such objects may late bind to the unit under test. An accessor class may facilitate late binding to the specific unit under test while allowing tests authored in the development environment to use context sensitive information needed to access the unit under test.