A unit test extending system and method use a unit test extender engine and a test pattern to extend a unit test written to validate code under test. The unit test has a first function configured to return a single hard coded value to the code under test. A test pattern database stores test patterns for different hard coded value data types. The unit test extender engine identifies a data type of the hard coded value of the first function in the unit test and retrieves one of the test patterns from the test pattern database. The engine then automatically calls the first function in the unit test a plurality of times, each time returning a different one of a plurality of different values in the retrieved test pattern in order to automatically extend the unit test.