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This mutator inserts a unary operator (increment or decrement) to a variable call. The mutator is composed of 5 sub-mutators (ROR1 to ROR5) that mutate the operators according to the table below. This mutator replaces a relational operator with another one. Relational Operator Replacement Mutator (ROR) Table: Java Default Values for Primitives and Reference Types Type The members will be initialized with their Java Default Value for the specific
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The mutator can even remove assignments to final members. The experimental member variable mutator mutates classes by removing assignments Experimental MutatorsĮxperimental Argument Propagation (EXPERIMENTAL_ARGUMENT_PROPAGATION)Įxperimental mutator that replaces method call with one of its parameters of matching type.Įxperimental Big Integer (EXPERIMENTAL_BIG_INTEGER)Įxperimental mutator that swaps big integer methods.Įxperimental Naked Receiver (EXPERIMENTAL_NAKED_RECEIVER)Įxperimental mutator that replaces method call with a naked receiver.Įxperimental Member Variable Mutator (EXPERIMENTAL_MEMBER_VARIABLE) Optional mutator that removes local variable increments. Remove Increments Mutator (REMOVE_INCREMENTS) The reason these are not enabled by default is that there is a large degree of overlap in the tests required to kill these mutations and those required to kill mutations from other default operators such as the conditional boundaries mutator.
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The names reflect which branch will be forced to execute (the “if” or the “else”) and the type of checks that will be mutated. Specialisations also exist that will mutate the bytecode instructions for order checks (eg ). Replace non- null return values with null and throw a if the unmutated method would return null Replace the unmutated return value x with the result of -(x+1.0) if x is not NAN and replace NAN with 0 Replace the unmutated return value x with the result of x+1 If the unmutated return value is 0 return 1, otherwise mutate to return value 0 Replace the unmutated return value true with false and replace the unmutated return value false with true On the return type of the method another mutation is used. The return values mutator mutates the return values of method calls. See Empty returns, False returns, True returns, This mutator has been superseded by the new returns mutator set. Mutations are generally easier for a test suite to detect. This mutator overlaps to a degree with the conditionals boundary mutator, but is less stable i.e these With their boundary counterpart as per the table below. The conditionals boundary mutator replaces the relational operators, >=
#The visitor returns mutation kill code
See the current code for current list (latest development version).Ĭonditionals Boundary Mutator (CONDITIONALS_BOUNDARY) The following table list available mutators and whether or not they are part of a group : Mutators Those operators that do not meet these requirements are not enabled by default. The operators are largely designed to be stable (i.e not be too easy to detect) and minimise the number of equivalent mutations that they generate. This approach has the advantage of being generally much faster and easier to incorporate into a build, but it can sometimes be difficult to simply describe how the mutation operators map to equivalent changes to a Java source file.
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Mutations are performed on the byte code generated by the compiler rather than on the source files. Parameter will activate all mutators of the group. Passing the name of a group in the mutators To make configuration easier, some mutators are put together in groups. The default set can be overridden, and different operators selected, by passing the names of the required operators to the mutators parameter. PIT currently provides some built-in mutators, of which most are activated by default.