Mining Test Inputs for Effective Test Generation
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TestMiner extracts test input values, such as strings, from a corpus of existing tests and suggests these values to a test generation tool. The approach is described in our ASE 2017 paper:

Saying ‘Hi!’ Is Not Enough: Mining Inputs for Effective Test Generation
Luca Della Toffola (ETH Zurich, Switzerland)
Cristian-Alexandru Staicu, Michael Pradel (TU Darmstadt, Germany)

This short tutorial shows how to build and use TestMiner.


The Maven Central index retrieval and the static analysis framework are written in Scala/Java. We have two (almost) equivalent implementation of TestMiner, one written in Python, and another written in Java. The minimum software requirements to run and compile TestMiner are:

  • Java Virtual Machine (version 7 or greater)
  • Python (version 2.7 or greater)
  • Gradle (version 3.3 or greater)
  • Scala (version 2.10.x or greater)

A problem related to zinc may cause a compilation issue using Gradle. An alternative solution to compile TestMiner is to use Docker with a script similar to:

FROM frekele/gradle:3.3-jdk8 
USER root 
WORKDIR /source 
COPY . /source 
RUN gradle


The first three steps indicated below are optional. The three applications are used to prepare the context-value pairs that TestMiner uses as index. However in the repository we provide two ready-to-use data-sets in the directory indexer/src/main/resources:

  • full.json: this file contains all the context-value pairs that we extracted from test-cases in 3600 projects we downloaded from Maven Central.
  • evaluation.json: this file contains all the context-value pairs that we used in the evaluation. In this data-set we removed all the method signatures that are prefixed with one of the class-under-test. The file packages_to_filter.txt contains the prefixes that are filtered.

The snapshot date for the data is 19-02-2017. If you desire to get obtain an updated set of strings you can execute three steps otherwise TestMiner is ready to be used (see step 4.).

1. Download Maven Central index (optional)

This application downloads the Maven Central index, but not the entire repository containing the Jar archives of the source-code. The index is required to extract the list of projects that will be parsed later on.

> gradle -p analysis index -Dexec.args=/path/to/index

2. Download and analysis of projects source-code (optional)

This application downloads and analyzes the projects Jar archives with the source-code. Only the Jar archive that use one of the libraries in parser/src/main/resources/top100.csv are downloaded. This is an heuristic to reduce the number of projects that are downloaded and analyzed.

> gradle -p analysis parse -Dexec.args=/path/to/index,/path/to/parsed

In addition to the source-code the application also downloads the JavaDoc for a project.


3. Process parsed source-code (optional)

To transform the analyzed source-code in a form ready to be indexed by TestMiner we provide the script To display all the command-line options use the command:

python --help

The output of the command is supposed to be:

usage: [-h] [--input INPUT] [--output OUTPUT] [--type TYPE]
                     [--filter] [--use-generics]

TestMiner dataset pre-processor

optional arguments:
  -h, --help       show this help message and exit
  --input INPUT    specifies the resulting directory with the parsed of data
  --output OUTPUT  specifies the directory where to save the elaborated data
  --type TYPE      specifies the primitive type to export (e.g., string -> only type supported)
  --filter         specifies to filter tuples that are part of testing set
  --use-generics   specifies to include generics of the method signature

The example command below executes the script with the results of the analysis for the source-code:

python --input /path/to/parsed --output /path/to/dataset.json

To filter the context-value tuples used in the evaluation use the option --filter.

4. Run TestMiner

We currently provide two ways for running TestMiner. First, a standalone bundle (bundles/test-miner.jar) that can be used for generating arbitrary strings for a given context. The main method to be used is testminer.TestMiner.query(String) that accepts a context and returns a set of string constants for that context. The second way to run TestMiner is to use the Randoop+TestMiner bundled version (bundles/randoop-with-test-miner.jar) that can be run as described by the randoop manual. For example, you can generate tests from the sample\_project directory in the following way (you need to first compile the ValidatorClass into the bin folder):

java -ea -classpath ./bin:../bundles/randoop-with-test-miner.jar  randoop.main.Main gentests --testclass=de.tu.darmstadt.sola.ValidatorClass  --junit-output-dir=tests  --junit-package-name=de.tu.darmstadt.sola  --timelimit=60