metamutator: a meta-mutation tool for Java

Build Status

metamutator takes as input a program and produces a metaprogram which contains all possible mutations inserted at compile-time according to a mutant schemata. It is a Java implementation of "Mutation analysis using mutant schemata". However, the mutations are all deactivated by default, meaning that the metaprogram behaves as the original one. Metamutants can be activated and deactivated one by one at runtime.

Mutation operators


Let's assume your project is called foo and contains two folders src/main/java and src/test/java with a test class PgmTest.

Install metamutator

git clone
cd metamutator
mvn package
# now we have target/metamutator-*-jar-with-dependencies.jar

Create the metaprogram

java -jar target/metamutator-*-jar-with-dependencies.jar -i src/main/java -p metamutator.LogicalExpressionMetaMutator -o spooned

Compile the metaprogram

javac `find spooned -name "*.java"`

Run the test class (with the metaprogram in the classpath and not the original program)



Based on awesome code by Carlos Fau and Alejandro Russel (

Great contributions from University of Lille's students enrolled in IAGL 2015-2016.