ShrinkOnFailure.java

/*******************************************************************************
 * Copyright (c) 2025 Eclipse RDF4J contributors.
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Distribution License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 ******************************************************************************/
package org.eclipse.rdf4j.queryrender;

import static org.junit.jupiter.api.Assertions.fail;

import org.junit.jupiter.api.function.Executable;

/**
 * Wraps a query assertion. If it fails, runs the shrinker and rethrows with the minimized query.
 *
 * Usage inside a DynamicTest body: ShrinkOnFailure.wrap(q, () -> assertRoundTrip(q), failureOracle);
 */
public final class ShrinkOnFailure {
	private ShrinkOnFailure() {
	}

	public static void wrap(String query,
			Executable assertion,
			SparqlShrinker.FailureOracle oracle) {
		try {
			assertion.execute();
		} catch (Throwable t) {
			try {
				SparqlShrinker.Result r = SparqlShrinker.shrink(
						query,
						oracle,
						null, // or a ValidityOracle to enforce validity during shrinking
						new SparqlShrinker.Config()
				);
				String msg = "Shrunk failing query from " + query.length() + " to " + r.minimized.length() +
						" chars, attempts=" + r.attempts + ", accepted=" + r.accepted +
						"\n--- minimized query ---\n" + r.minimized + "\n------------------------\n" +
						String.join("\n", r.log);
				fail(msg, t);
			} catch (Exception e) {
				fail("Shrink failed: " + e.getMessage(), t);
			}
		}
	}
}