1. A method for testing functionality of a computer program based on at least one change to program code of the computer program comprising: a computer identifying one or more program functions within program code of a computer program affected by a program code change; the computer identifying program function calls made by the one or more program functions to other program functions; the computer adding the one or more program functions and program function calls to a program code database; the computer generating a mapping of relationships between the program functions of the program code; and the computer selecting one or more test scripts based on the mapping of relationships.