import junit.framework.ComparisonFailure;

public class CustomComparisonFailure extends ComparisonFailure {

    /**
     * Constructs a comparison failure.
     *
     * @param message  the identifying message or null
     * @param expected the expected string value
     * @param actual   the actual string value
     */
    public CustomComparisonFailure(String message, String expected, String actual) {

import spock.lang.Specification

class JUnitComparisonTestFailureMapperTest extends Specification {

    def "can correctly map custom comparison exceptions"() {
        given:
        def comparisonFailure = new CustomComparisonFailure("message", "expected", "actual")
        def mapper = new JUnitComparisonTestFailureMapper()

        when:
        def supports = mapper.supports(comparisonFailure.class)
        then:
        supports