"should return different hash codes for non equal objects" seem to be using equal objects

[adamsiemion]

I have a test that from time to time fails in my Jenkins instance, but never failed on my local machine.

It fails with the following message:

Class EntityClass has bad 'hashCode' method implementation.
The hashCode method should return different hash codes for non equal objects.
Current implementation returns same hash codes.
Object:
EntityClass(f1=www.pojo.pl, f2=www.pojo.pl, f3=-4, f4=Fri Mar 10 14:52:19 UTC 2017, f5=www.pojo.pl, f6=www.pojo.pl)
and
EntityClass(f1=www.pojo.pl, f2=www.pojo.pl, f3=-4, f4=Fri Mar 10 14:52:19 UTC 2017, f5=www.pojo.pl, f6=www.pojo.pl)
should have different hash codes:
38708309
and
38708309

Class code:

@Getter
@ToString
@EqualsAndHashCode
@AllArgsConstructor
@NoArgsConstructor(access = AccessLevel.PACKAGE)
public class EntityClass {

    private String f1;
    private String f2;
    private int f3;
    private Date f4;
    private String f5;
    private String f6;
}

and this is my test

assertPojoMethodsFor(EntityClass.class)
        .testing(GETTER, TO_STRING, CONSTRUCTOR, EQUALS, HASH_CODE)
        .areWellImplemented();

I suspect the Date f4 field is the same and it is causing issues.
BTW. Is there a way to change the test (as I cannot change the production code) so that when it fails, a custom message (provided function) is used instead of toString()? Something along these lines:

    assertPojoMethodsFor(EntityClass.class)
            .testing(GETTER, TO_STRING, CONSTRUCTOR, EQUALS, HASH_CODE)
            .areWellImplemented()
            .messageWhenFails((o1, o2) -> "o1 date" + o1.f4 + " and o2 date" + o2.f4);

[sta-szek]

Thanks for reporting!
As you suggested, the problem is caused by java.util.Date class, as pojo-tester does not know how to change instance of that class to make them different.

The solution is to implement another one field value changer.

In this issue I will add following field value changers to pojo-tester:

• DateFieldValueChanger (java.util.Date)
• InstantFieldValueChanger (java.time.Instant)
• LocalDateFieldValueChanger (java.time.LocalDate)
• LocalDateTimeFieldValueChanger (java.time.LocalDateTime)
• LocalTimeFieldValueChanger (java.time.LocalTime)
• ZonedDateTimeFieldValueChanger (java.time.ZonedDateTime)
• SqlDateFieldValueChanger (java.sql.Date)

And unfortunately there is no way to define custom message. If you wish so, please report feature request.

Have you got any suggestions?

[sta-szek]

BTW, for now you can workaround this as follows:

package pl.pojo.tester.issue187;


import org.junit.jupiter.api.Test;
import pl.pojo.tester.internal.field.AbstractFieldValueChanger;
import pl.pojo.tester.internal.field.DefaultFieldValueChanger;

import java.time.Instant;
import java.util.Date;

import static pl.pojo.tester.api.assertion.Assertions.assertPojoMethodsFor;
import static pl.pojo.tester.api.assertion.Method.*;

public class EntityClassPojoTest {

    @Test
    public void Should_Test_Entity_Class() {
        for (int i = 0; i < 10000; i++) {
            final AbstractFieldValueChanger fieldValueChanger = DefaultFieldValueChanger.INSTANCE.attachNext(new DateFieldValueChanger());
            assertPojoMethodsFor(EntityClass.class).testing(GETTER, TO_STRING, CONSTRUCTOR, EQUALS, HASH_CODE)
                                                   .using(fieldValueChanger)
                                                   .areWellImplemented();
        }
    }

    class DateFieldValueChanger extends AbstractFieldValueChanger<Date> {

        @Override
        public boolean areDifferentValues(final Date sourceValue, final Date targetValue) {
            return !sourceValue.equals(targetValue);
        }

        @Override
        protected Date increaseValue(final Date value, final Class<?> type) {
            final Instant nextDay = value.toInstant().plusSeconds(86_400);
            return Date.from(nextDay);
        }

        @Override
        protected boolean canChange(final Class<?> type) {
            return type.equals(Date.class);
        }
    }

}

[adamsiemion]

Great stuff! Thank you for a prompt reply.

[adamsiemion]

@sta-szek Great job, thanks! Quick question, when 0.7.5 will be released?

[sta-szek]

Due by March 19, 2017