Question Authors' Forum

It's in the topmost panel of the question authoring form, as shown in the figure below. However, it's a new feature and may not be in your version of CodeRunner. It's only relevant when you're randomising questions, so if this is still about adding prolog to CodeRunner you can ignore it.

I think the main problem with your template is that the Twig QUERY variable is undefined. Probably should be a field from the TEST variable, e.g. TEST.testcode?

I'm not sure what sort of question you want to ask, but it looks like you want the students to write the Prolog program and your tests will then run queries against that? If so, a possible template is the following. It's more or less what you had, except I've replaced QUERY with TEST.testcode. 

""" A generalized template for running any Prolog code and query. """

import subprocess, sys

# Write the student's Prolog code to a file prog.pl
student_answer = """{{ STUDENT_ANSWER | e('py') }}"""
with open("prog.pl", "w") as src:
    print(student_answer, file=src)

# Define the query dynamically (e.g., from a parameter or input)
query = """{{ TEST.testcode | e('py') }}""".strip() + '\n'

# Run the Prolog program with the query
try:
    # Use SWI-Prolog to execute the query
    result = subprocess.run('swipl -q -s prog.pl'.split(),
                        capture_output=True,
                        text=True,
                        check=True,
                        input=query)
    
    if result.stderr:
        # Print errors if any
        print(result.stderr, file=sys.stderr)
    else:
        # Print the actual output
        print(result.stdout.rstrip())
    
except subprocess.CalledProcessError as e:
    # Handle errors during execution
    print(e.stdout.rstrip())
    print(e.stderr.rstrip())
    if e.returncode > 0:
        # Non-zero return codes indicate runtime errors
        print("** Prolog runtime error **", file=sys.stderr)
    else:
        # Negative return codes indicate signals (e.g., segmentation fault)
        if e.returncode < 0:
            print("Task failed with signal", -e.returncode, file=sys.stderr)
        print("** Further testing aborted **", file=sys.stderr)

This could be used in questions like the following (with apologies for the kindergarten-level Prolog - I learnt a bit about 40 years ago and haven't touched it since!):

I attach the XML exports of the prototype and the example question. But you'll undoubtedly want to tune the prototype, and you'll need to investigate the error behaviour - I don't know how swi-prolog behaves.

An obvious defect of that example is that a student could simply provide facts that match the tests, rather than writing any predicates. So you'd at very least need some hidden test cases. And a lot more thorough definition of what the program is meant to define.