An automatic test data generator for C functions.
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IGUANA (Input Generation Using Automated Novel Algorithms) Test Data Generation Tool for C

IGUANA is a tool for generating branch coverage test data for C functions.


IGUANA requires the Maven build automation tool, JDK 7 (or more recent) installed, and a C compiler (e.g., gcc).

The Bash shell is also recommended – the instructions provided here assume its use and the script needed to install the accompanying casestudies repository requires it/has only been tested using it.


To install IGUANA you need to check out the repository, and run the following command to produce a JAR file (or run the equivalent command in your IDE):

mvn package

You'll then need to set the following environment variables.

  • The IGUANA_HOME environment variable needs to be set to the root directory of this repository, where it is checked out on your system.
  • The JAVA_HOME environment variable needs to be set to the root directory of your JDK installation.
  • You need to update your CLASSPATH environment variable to the JAR file (that includes dependent libraries) produced by Maven. Typically this lives in the target directory and is called iguanatool-1.0-jar-with-dependencies.jar. So in Bash, you will need to use the command:

export CLASSPATH="$IGUANA_HOME/target/iguanatool-1.0-jar-with-dependencies.jar":$CLASSPATH

Compiling Case Studies

To use IGUANA to generate test data for a C function, you need to include it as part of a "case study". A "case study" comprises a set of C functions you want to test, also referred to as "test objects".

You will need to create a directory for your case studies. The easiest way to do this with the required structure is to clone the casestudies repository, available at

To install a new case study you will need to perform the following steps:

  1. Create a new directory for your case study in the c subdirectory of your casestudies directory, e.g. my_example and place the C function you want to test in a file called my_example.c where my_example is the name of your case study.
  2. Perform step one assimilation, by running the following command java org.iguanatool.Assimilate my_example (replace my_example with your own case study name)
  3. Edit the input specification Java code for the .java class generated for each test object (C function) to be tested. The source code for each class resides in the casestudies/java/my_example/inputspecifications directory (see the next section if you need further instructions or help with this).
  4. Each case study becomes a part of the IGUANA code, so you'll now need to compile IGUANA again, using mvn package
  5. Complete the call code for each C file for each test object (C function to be tested) in the casestudies/c/my_example/call directory (see the next section if you need help with this).
  6. Perform step two assimilation, by again running java org.iguanatool.Assimilate my_example

Your case study should be ready to go.

If you experience C compiler errors this could be due to a few reasons:

  • Your C code contains errors (check, by trying to compile it separately, and remove the errors)
  • Your C code cannot be parsed by the IGUANA C parser (you could try to reformat your C code so that it can be handled by the parser)
  • There is a problem with your compiler or the compilation command being used. The compiler file used by default is named on the basis of the OS you're using and lives in the ccompilers directory. Check if any part of the command being used to compile your code needs to be changed, or adapted to your system.

Setting up the Input Specification Java code and Bridging C code in the Case Study's call Directory

At its core, IGUANA optimizes a fixed vector of double variables. Java code needs to be written to specify this vector, and C code needs to be written to map it to the input arguments that each function under test expects.

The code that must be written to specify the vector of double variables to be optimized for each test object lives in the inputspecifications Java package for your case study, which is located in the case study's subdirectory created in the java directory of your casestudies repository. Each test object will have its own Java class generated as part of step one assimilation detailed above. You need to complete the code in the defaultSetup method of this class to set the bounds of each variable to be optimized by IGUANA. For example, if the C function under test involves three integer inputs, in the range 0-255, the code to specify this would be addInt(3, 0, 255);. For more information on the method calls that can be used to specify the input arguments to the C function, see the code for the org.iguanatool.testobject.InputSpecification class. (For an example of this, see the calendar case study already provided in the casestudies repository.)

After the input specification is complete, you then need to set up a bridge so that the vector of double variables generated by IGUANA can be translated into input arguments for each test object / C function under test. This link must be written in C. You need to complete the stub automatically generated for each test object in the call directory for that lives in the case study subdirectory under the c directory in your casestudies repository. In this stub, you first need to set the NUM_ARGS constant to the correct number of arguments that the function will accept. This number should match the number of arguments you specified in the Java code for the test object's input specification. Then, you need to cast each element of the double array passed into the perform_call function to the correct type for the function under test, and then pass those values to the function under test so that it can be executed with the data. (For an example of this, see the calendar case study already provided in the casestudies repository.)

Running Test Data Generation

Running test data generation is then as simple as a command such as

java org.iguanatool.Run my_example nhc

where my_example is the case study and nhc is the search. (Search names are derived from the method names in the class.)

IGUANA will now attempt to generate test inputs for each test object (C function) that is a part of your case study. The list of C functions for which data are generated can be changed by editing the testobjects file placed in the case study directory in which your C code lives. This is initially populated with all the functions IGUANA found when parsing your case study C file (i.e., my_example.c in the above).

Further configuration options can be set through the iguana.config file in IGUANA's root directory. Each of these can be overridden at the command line by preceeding the option with a dash. For example, to set the seed from the command line, use

java org.iguanatool.Run my_example nhc -seed=100