Methods for testing a computer program after changing a first version of the computer program into a second version of the computer program due to a revision of the computer program are provided. In one aspect, the method includes determining mutations inserted into the first version of the computer program, and the mutations inserted into the second version of the computer program, and comparing the first version of the computer program with the second version of the computer program to determine changed and unchanged mutations in the second version against the first version. The mutations that can be inserted only in the first version of the computer program or only in the second version of the computer program are classified as changed mutations and the mutations that can be inserted in the first and the second version are classified as unchanged mutations.