Nopol

Nopol is an automatic software repair tool for Java. This code is research code, released under the GPL licence.

If you use this code for academic research, please cite: Nopol: Automatic Repair of Conditional Statement Bugs in Java Programs (Jifeng Xuan, Matias Martinez, Favio Demarco, Maxime Clment, Sebastian Lamelas, Thomas Durieux, Daniel Le Berre, Daniel Le Berre, Martin Monperrus). IEEE Transactions on Software Engineering, 2016. Bibtex @article{xuan:hal-01285008, title = {Nopol: Automatic Repair of Conditional Statement Bugs in Java Programs}, author = {Xuan, Jifeng and Martinez, Matias and Demarco, Favio and Clment, Maxime and Lamelas, Sebastian and Durieux, Thomas and Le Berre, Daniel and Monperrus, Martin}, journal = {IEEE Transactions on Software Engineering}, doi = {10.1109/TSE.2016.2560811}, year = {2016}, }

Others papers about Nopol: * "Automatic Repair of Buggy If Conditions and Missing Preconditions with SMT" (Favio DeMarco, Jifeng Xuan, Daniel Le Berre, Martin Monperrus), In Proceedings of the 6th International Workshop on Constraints in Software Testing, Verification, and Analysis (CSTVA 2014) (Bibtex) * DynaMoth: Dynamic Code Synthesis for Automatic Program Repair (Thomas Durieux, Martin Monperrus), In Proceedings of the 11th International Workshop in Automation of Software Test, 2016, describes the dynamic synthesis part of Nopol (Bibtex)
* Automatic Repair of Infinite Loops (Sebastian Lamelas-Marcote and Martin Monperrus), Technical report hal-01144026, University of Lille, 2015, describes the Infinitel part. (Bibtex)

Getting started

Nopol requires Java and an SMT solver installed on the machine (e.g. Z3)

Java version:

• From 2013 to 2021, Nopol required Java 8.
• From Nov 19, 2021, Nopol works on Java 11, see https://github.com/SpoonLabs/nopol/pull/214
• From August 8 2024, Nopol works with Java 18, see https://github.com/SpoonLabs/nopol/pull/234

0) NoPol uses the com.sun.jdi that lives in tools.jar. Identify where tools.jar is and add the depencency in pom.xml

<dependency> <groupId>com.sun</groupId> <artifactId>tools</artifactId> <version>1.6.0</version> <scope>system</scope> <!-- replace this path by yours --> <systemPath>/home/martin/martin-no-backup/jdk1.8.0_40/lib/tools.jar</systemPath> </dependency>

2) Compile NoPol:

``` git clone https://github.com/SpoonLabs/nopol.git cd nopol/nopol export JAVA_HOME=/usr/lib/jvm/java-8-openjdk-amd64

-DskipTests is required, to run the tests one needs to compile ../test-projects/ (see below)

mvn package -DskipTests ```

2) Locate the Nopol jar file produced at step 1)

$ ls target/*jar target/nopol-0.2-SNAPSHOT.jar target/nopol-0.2-SNAPSHOT-jar-with-dependencies.jar # we use this one In the following, nopol.jar refers to the jar file with dependencies (target/nopol-<VERSION>-SNAPSHOT-jar-with-dependencies.jar)

3) Compile the test-projects

``` $ cd ../test-projects/

compiling app (in target/classes) and tests (in target/test-classes), but don't run the tests (they obviously fail, because the goal is to repair them)

$ mvn test -DskipTests ``` 3b) Optional: run the tests of Nopol to check your installation

$ cd ../nopol/ $ mvn test

4) Execute Nopol (parameters explained below)

(Long commands are broken in several lines, separated by a backslash, which means an escaped linebreak in Unix shells.)

cd ../test-projects/ java -jar nopol.jar \ -s src/main/java/ \ -c target/classes:target/test-classes:/home/<user>/.m2/repository/junit/junit/4.11/junit-4.11.jar:/home/<user>/.m2/repository/org/hamcrest/hamcrest-core/1.3/hamcrest-core-1.3.jar \ -t symbolic_examples.symbolic_example_1.NopolExampleTest \ -p ../nopol/lib/z3/z3_for_linux

If you keep nopol.jar instead of the actual jar located at the previous step, you'll get Error: unable to access jarfile nopol.jar (see above). You should replace also <user> by your own username.

It should output something like: ----INFORMATION---- Nb classes : 34 Nb methods : 53 Nb statements: 5 Nb statement executed by the passing tests of the patched line: 0 Nb statement executed by the failing tests of the patched line: 0 Nb unit tests : 9 Nb Statements Analyzed : 3 Nb Statements with Angelic Value Found : 1 Nb inputs in SMT : 8 Nb SMT level: 2 Nb SMT components: [4] [== of arity: 2, != of arity: 2, < of arity: 2, <= of arity: 2] class java.lang.Boolean: 4 Nb variables in SMT : 13 Nb run failing test : [2, 1] Nb run passing test : [4, 18] NoPol Execution time : 3262ms ----PATCH FOUND---- symbolic_examples.symbolic_example_1.NopolExample:12: CONDITIONAL index < 1

NoPol (SMT and Dynamoth) returns also a unix code (integer): * 0 if a patch has been found * -1 otherwise

Parameter -c can be found with mvn dependency:build-classpath.

Minimal Usage

4 parameters are required ``` Usage: java -jar nopol.jar

(-s|--source) source1:source2:...:sourceN Define the path to the source code of the project. For instance src/main/java

(-c|--classpath) Define the classpath of the project separated by a path separator (: on Linux). Must contain the application binary classes (target/classes) Must contain the application test classes (target/test-classes) Must contain the library classes (lib/junit.jar for instance)

[(-t|--test) test1:test2:...:testN ] Define the tests of the project. For instance symbolic_examples.symbolic_example_1.NopolExampleTest

[(-p|--solver-path) ] Define the solver binary path (only used with smt synthesis). For instance ../nopol/lib/z3/z3_for_linux

```

Advanced Usage

See also notes below.

``` Usage: java -jar nopol.jar

[(-m|--mode) ] Define the mode of execution. (default: repair)

[(-e|--type) ] The type of statement to analyze (only used with repair mode). (default: prethencond)

[(-o|--oracle) ] Define the oracle (only used with repair mode). (default: angelic)

[(-y|--synthesis) ] Define the patch synthesis. (default: smt)

[(-l|--solver) ] Define the solver (only used with smt synthesis). (default: z3)

[--complianceLevel ] The Java version of the project. (default: 7)

[--maxTime ] The maximum time execution in minute for the whole execution of Nopol.(default: 10)

[--maxTimeType ] The maximum time execution in minute for one type of patch per per suspicious statement (eg. 5 minutes max to find a precondition at line x). (default: 5)

[(-z|--flocal) < cocospoon|dumb|gzoltar>] Define the fault localizer to be used. (default: cocospoon). "cocospoon" means source code instrumentation plus ochiai metric. "dumb" means random fault localization. "gzoltar" means binary code instrumentation with external library plus ochiai metric.

```

Notes: For using Dynamoth (-y dynamoth), you must add tools.jar in the classpath of Nopol, and use java with -cp (and not -jar):

java -cp $JAVA_HOME/lib/tools.jar:../nopol/target/nopol-SNAPSHOT-jar-with-dependencies.jar fr.inria.lille.repair.Main <nopol arguments>

Examples of Real Bugs Targeted by Nopol:

Apache Commons Math:

• CM1 https://github.com/apache/commons-math/commit/eb4d267f51ff192b928be1d85ccb5f56015f19d3 (Percentile)
• CM2 http://svn.apache.org/viewvc?view=revision&revision=141217 (MathUtils)
• CM3 http://svn.apache.org/viewvc?view=revision&revision=141473 (MathUtils, "Changed factorial methods to return 1 for argument = 0.")
• CM3 https://github.com/apache/commons-math/commit/dabf3a5beb9ab697d570154b9961078a8586c787 (MathUtils, "fixed overflow error in gdc computation, JIRA: MATH-238)
• CM7 https://github.com/apache/commons-math/commit/0596e3145c1a8a9c42185fe688c42b0830b64516 (RandomDataImp, "Fixed parameter test in RandomDataImpl#nextExponential. JIRA: MATH-309.")
• CM10 https://github.com/apache/commons-math/commit/49444ee6a56caee4eddc32c24dd960dd3195f7fa (Covariance, "Allow covariance to be computed for one-dimensional variables. JIRA: MATH-939")
• PM2 https://github.com/apache/commons-math/commit/318d66e1b170a3b57d54d7175cfb3e495f6d7fda (MessageFactory, "allow either specific or generic formats to be null")

Apache Commons Lang:

• CL2 https://github.com/apache/commons-lang/commit/80da42a808874e691f70654446477421edf53e46 (StringUtils, "Handles empty string now as well.")
• CL3 https://github.com/apache/commons-lang/commit/9a51cf5efc8b2b345a02f4d18e5800ca498d82cd (StringUtils, "Relax exceptions in left(), right() and mid()")
• CL4 https://github.com/apache/commons-lang/commit/2f6b0b2c69b626d6a669aa8add3223417b3b274e (StrBuilder, "Fix indexOf and lastIndexOf with null input")

Google GSON:

• https://github.com/google/gson/commit/9a24219 (Apr 19, 2017, "negative zero test and fix")

Contact

For questions and feedback , please contact @monperrus