@ParametersAreNonnullByDefault should mean fields are too

[Pr0methean]

What steps will reproduce the problem?

Create a class annotated with @ParametersAreNonnullByDefault and a final object field that's not @Nullable, and test it with EqualsVerifier.

What is the code that triggers this problem?

Class under test:

package io.github.pr0methean.betterrandom.util;

import java.util.Objects;
import javax.annotation.ParametersAreNonnullByDefault;

@ParametersAreNonnullByDefault
public class EqualsVerifierBugExample {
  private final String name;
  private final int age;

  public EqualsVerifierBugExample(String name, int age) {
    this.name = name;
    this.age = age;
  }

  @Override public boolean equals(Object o) {
    if (this == o) {
      return true;
    }
    if (o == null || getClass() != o.getClass()) {
      return false;
    }
    EqualsVerifierBugExample that = (EqualsVerifierBugExample) o;
    return age == that.age && name.equals(that.name);
  }

  @Override public int hashCode() {
    return Objects.hash(name, age);
  }
}

Test:

package io.github.pr0methean.betterrandom.util;

import nl.jqno.equalsverifier.EqualsVerifier;
import org.testng.annotations.Test;

public class EqualsVerifierBugExampleTest {
  @Test public void testWithEqualsVerifier() {
    EqualsVerifier.forClass(EqualsVerifierBugExample.class).verify();
  }
}

What error message or stack trace does EqualsVerifier give?

java.lang.AssertionError: EqualsVerifier found a problem in class io.github.pr0methean.betterrandom.util.EqualsVerifierBugExample.
-> Non-nullity: equals throws NullPointerException on field name.

For more information, go to: http://www.jqno.nl/equalsverifier/errormessages

	at nl.jqno.equalsverifier.api.SingleTypeEqualsVerifierApi.verify(SingleTypeEqualsVerifierApi.java:269)
	at io.github.pr0methean.betterrandom.util.EqualsVerifierBugExampleTest.testWithEqualsVerifier(EqualsVerifierBugExampleTest.java:8)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:566)
	at org.testng.internal.MethodInvocationHelper.invokeMethod(MethodInvocationHelper.java:133)
	at org.testng.internal.TestInvoker.invokeMethod(TestInvoker.java:584)
	at org.testng.internal.TestInvoker.invokeTestMethod(TestInvoker.java:172)
	at org.testng.internal.MethodRunner.runInSequence(MethodRunner.java:46)
	at org.testng.internal.TestInvoker$MethodInvocationAgent.invoke(TestInvoker.java:804)
	at org.testng.internal.TestInvoker.invokeTestMethods(TestInvoker.java:145)
	at org.testng.internal.TestMethodWorker.invokeTestMethods(TestMethodWorker.java:146)
	at org.testng.internal.TestMethodWorker.run(TestMethodWorker.java:128)
	at org.testng.TestRunner$$Lambda$187/0000000000000000.accept(Unknown Source)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1540)
	at org.testng.TestRunner.privateRun(TestRunner.java:770)
	at org.testng.TestRunner.run(TestRunner.java:591)
	at org.testng.SuiteRunner.runTest(SuiteRunner.java:402)
	at org.testng.SuiteRunner.runSequentially(SuiteRunner.java:396)
	at org.testng.SuiteRunner.privateRun(SuiteRunner.java:355)
	at org.testng.SuiteRunner.run(SuiteRunner.java:304)
	at org.testng.SuiteRunnerWorker.runSuite(SuiteRunnerWorker.java:53)
	at org.testng.SuiteRunnerWorker.run(SuiteRunnerWorker.java:96)
	at org.testng.TestNG.runSuitesSequentially(TestNG.java:1180)
	at org.testng.TestNG.runSuitesLocally(TestNG.java:1102)
	at org.testng.TestNG.runSuites(TestNG.java:1032)
	at org.testng.TestNG.run(TestNG.java:1000)
	at com.intellij.rt.testng.IDEARemoteTestNG.run(IDEARemoteTestNG.java:66)
	at com.intellij.rt.testng.RemoteTestNGStarter.main(RemoteTestNGStarter.java:110)
Caused by: nl.jqno.equalsverifier.internal.exceptions.AssertionException
	at nl.jqno.equalsverifier.internal.util.Assert.fail(Assert.java:75)
	at nl.jqno.equalsverifier.internal.checkers.fieldchecks.NullPointerExceptionFieldCheck.npeThrown(NullPointerExceptionFieldCheck.java:71)
	at nl.jqno.equalsverifier.internal.checkers.fieldchecks.NullPointerExceptionFieldCheck.handle(NullPointerExceptionFieldCheck.java:60)
	at nl.jqno.equalsverifier.internal.checkers.fieldchecks.NullPointerExceptionFieldCheck.performTests(NullPointerExceptionFieldCheck.java:49)
	at nl.jqno.equalsverifier.internal.checkers.fieldchecks.NullPointerExceptionFieldCheck.execute(NullPointerExceptionFieldCheck.java:42)
	at nl.jqno.equalsverifier.internal.checkers.FieldInspector.check(FieldInspector.java:26)
	at nl.jqno.equalsverifier.internal.checkers.NullChecker.check(NullChecker.java:23)
	at nl.jqno.equalsverifier.api.SingleTypeEqualsVerifierApi.verifyWithoutExamples(SingleTypeEqualsVerifierApi.java:351)
	at nl.jqno.equalsverifier.api.SingleTypeEqualsVerifierApi.performVerification(SingleTypeEqualsVerifierApi.java:320)
	at nl.jqno.equalsverifier.api.SingleTypeEqualsVerifierApi.verify(SingleTypeEqualsVerifierApi.java:267)
	... 29 more
Caused by: java.lang.NullPointerException
	at io.github.pr0methean.betterrandom.util.EqualsVerifierBugExample.equals(EqualsVerifierBugExample.java:24)
	at nl.jqno.equalsverifier.internal.checkers.fieldchecks.NullPointerExceptionFieldCheck.lambda$performTests$1(NullPointerExceptionFieldCheck.java:49)
	at nl.jqno.equalsverifier.internal.checkers.fieldchecks.NullPointerExceptionFieldCheck$$Lambda$616/0000000000000000.run(Unknown Source)
	at nl.jqno.equalsverifier.internal.checkers.fieldchecks.NullPointerExceptionFieldCheck.handle(NullPointerExceptionFieldCheck.java:58)
	... 36 more

What did you expect?

EqualsVerifier recognizes @javax.annotation.ParametersAreNonnullByDefault and does not try to set any field to null unless it's annotated @Nullable.

Which version of EqualsVerifier are you using?

3.3

Please provide any additional information below.

Static analysis of the constructors would reveal that @Nullable immutable fields are always copied directly from @Nullable constructor parameters. For classes whose initialization isn't provably "trivial" in this sense, a workaround for the field/parameter disconnect might be to create the instances under test using constructors, only passing null to @Nullable parameters, or by cloning other instances that were created this way.

[jqno]

Hi, thanks for reporting this.

Indeed, EqualsVerifier doesn't support this annotation (yet). I wasn't familiar with it -- where does it come from? Do you have a Javadoc page or Maven coordinates or something, so that I can do some tests? I haven't been able to find that on google.

[Pr0methean]

It's from JSR305: https://www.javadoc.io/doc/com.google.code.findbugs/jsr305/3.0.1/javax/annotation/ParametersAreNonnullByDefault.html

…

On Wed., May 20, 2020, 05:41 Jan Ouwens, ***@***.***> wrote: Hi, thanks for reporting this. Indeed, EqualsVerifier doesn't support this annotation (yet). I wasn't familiar with it -- where does it come from? Do you have a Javadoc page or Maven coordinates or something, so that I can do some tests? I haven't been able to find that on google. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#308 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ABF3NBPNLWIC5R2MS4XVPFDRSPFYPANCNFSM4NFNQXYQ> .

[jqno]

Thanks! I'll look into it.

[jqno]

I've just released version 3.4, which adds support for @ParametersAreNonnullByDefault.