Declarative unit testing for answer set programming projects

pip install ansunit==0.1.7




Ansunit is a declarative testing framework for answer set programming (ASP). In particular, it targets the ASP tools from the Potassco project. Test suite descriptions are defined in YAML syntax, and they are executed within Python's unittest framework.


Install using pip install ansunit, then use the provided ansunit script on the command like:

$ ansunit tests.yaml


A test suite specification is a nested object definition in which important key names start with the word Test. Basic test specifications may define a program (a body of AnsProlog code), solver arguments (passed on the command line), and define an expectation for the result of running the program (regarding its satisfiability). Complex test specifications may make use of reusable modules described in a definitions specification. Tags and other test metadata may be included in the test name itself.

Test Keywords

  • Test ... defines a subtest
  • Program defines a literal piece of code (childen override parents)
  • Expect defines an outcome (SAT, UNSAT, or OPTIMAL)
  • Arguments defines a list of string arguments
  • Definitions defines a mapping from module names to definitions
  • Modules defines a list of modules that will participate in the test

Module Keywords

A module may be defined as...

  • some. inline. code. (a YAML string)
  • {filename: foo.lp}
  • {reference: another_module}
  • {group: [module_a, module_b]}


This simple specification defines two basic tests in canonical form (all details defined at the leaves of the specification).

Test a implies b:
    Program: |
        b :- a.
        :- not b.
    Expect: SAT
Test b not implies a:
    Program: |
        b :- a.
        :- not a.
    Expect: UNSAT

This complex specification defines four test cases (three of which are grouped into a common suite). A Definitions section defines several modules with complex indirect references that are to be used later. In the second test (suite) several variations on a common test setup are defined concisely by means of inheriting details defined in the enclosing suite. Now shown, it is also possible to define all details including Modules, Arguments, and even Program at the top level for use by inheritance.

    foo: {filename: foo.lp}
    bar: {filename: bar.lp}
    both: {group: [instance, encoding]}
    instance: {reference: bar}
    inline: |
        #const width = 3.
        { p(X) } :- dim(X).

Test twisted references:
        encoding: {reference: foo}
    Modules: both
    Expect: SAT

Test inline various:
    Modules: inline
    Expect: SAT

    Test small:
        Arguments: -c width=1 

    Test medium:
        Arguments: -c width=3 

    Test large:
        Arguments: -c width=5

Command line arguments

Run ansunit --help for more information.

Working with large test suites

Use the -m and -n (--filter_match and --filter_nomatch) arguments to select a focused subset of tests to run. A test is selected if it matches all positve conditions and no negative conditions. Conditions are checked by running on the whole test name -- the strings with ::.

For the demo_complex.yaml suite above, we might select tests in the various sweet excluding the large test with a command like this (using -l to list tests matching the conditions rather than executing them):

$ ansunit complex.yaml -m various -n large
- Test complex.yaml :: inline various :: large
* Test complex.yaml :: inline various :: medium
* Test complex.yaml :: inline various :: small
- Test complex.yaml :: twisted references


Created by Adam M. Smith (