assertThatThrownBy() check field on custom exception

Question

How can I check particular field value in my custom excepiton using assertJ?

Here is exception class:

public class SomeException extends RuntimeException {
    private final Set<Integer> something;

    public SomeException (String message, Set<Integer> something) {
        super(message);

        this.something = something;
    }

    public Set<Integer> getSomething() {
        return something;
    }
}

Here is my test:

    assertThatThrownBy(() -> service.doSomething())
        .isInstanceOf(SomeException.class)
        .hasMessageStartingWith("SomeException has 1,2,3,4 in something field. I want assert that")
        . ??? check that SomeException.getSomething() has 1,2,3,4 ???

The problem is that if I chain extracting() it will think I'm using Throwable. So I can't extract field something

Update:

SomeException throwable = (SomeException) catchThrowable(() -> service.doSomething(

assertThat(throwable)
    .hasMessageStartingWith("extracting() bellow still think we're working with Throwable")
    .extracting(SomeException::getSomething <<<--- doesn't work here)

I have tried following, as suggested bellow:

 assertThat(throwable)
        .hasMessageStartingWith("Works except containsExactlyInAnyOrder()")
        .asInstanceOf(InstanceOfAssertFactories.type(SomeException.class))
        .extracting(SomeException::getSomething)
        .->>>containsExactlyInAnyOrder<<<--- Not working!!!

But I can't use containsExactlyInAnyOrder() anymore :(

Please advise

You can catch the `Throwable` using `catchThrowable` and then make whatever assertions you want to on that (after casting to your type if necessary). — BeUndead, Oct 26 '20 at 16:34
Nice idea, unfortunately even if I hard cast SomeException throwable = (SomeException ) catchThrowable(() ... extracting() method doesn't take into account fields of SomeException — tillias, Oct 27 '20 at 08:57

score 19 · Answer 1 · answered Dec 15 '21 at 17:11

19

It looks like you're looking for catchThrowableOfType, which allows you to receive the correct class:

import static org.assertj.core.api.Assertions.catchThrowableOfType;

SomeException throwable = catchThrowableOfType(() -> service.doSomething(), SomeException.class);

assertThat(throwable.getSomething()).isNotNull();

answered Dec 15 '21 at 17:11

jamietanna

263
1
8
21

1

great advice, nice and clear way to handle it in unit tests – IHaveHandedInMyResignation Feb 14 '22 at 09:09
This should be the best and accepted answer! – Dmitriy Popov Sep 01 '22 at 08:55

Joel Costigliola · Accepted Answer · 2020-10-27T09:43:35.503

14

There are quite a few variations on extracting, the one you want to use is extracting(String), ex:

   assertThatThrownBy(() -> service.doSomething())
        .isInstanceOf(SomeException.class)
        .hasMessageStartingWith("SomeException ... ")
        .extracting("something")
        .isEqualTo(1,2,3,4);

Use extracting(String, InstanceOfAssertFactory) to get specialized assertions, so if the value is a collection you can try:

   assertThatThrownBy(() -> service.doSomething())
        .isInstanceOf(SomeException.class)
        .hasMessageStartingWith("SomeException ... ")
        .extracting("something", InstanceOfAssertFactories.ITERABLE)
        .contains();

You can also try: hasFieldOrPropertyWithValue

Update: working example

SomeException throwable = new SomeException("foo", Sets.newSet(1, 2, 3, 4));

assertThat(throwable).hasMessageStartingWith("fo")
                     .extracting("something", InstanceOfAssertFactories.ITERABLE)
                     .containsExactly(1, 2, 3, 4);

edited Oct 27 '20 at 09:43

answered Oct 27 '20 at 01:02

Joel Costigliola

6,308
27
35

this is close, but there is no such an overloaded method with InstanceOfAssertFactories.ITERABLE :( any ideas how can I cast first example (extracting("something")) to iterable type? – tillias Oct 27 '20 at 05:13
I have also tried casting throwable to my custom exception type as proposed in comment to my question, but exctracting() still things I'm working with Throwable instead of custom type. Please advise – tillias Oct 27 '20 at 08:57
tiillias I did not suggest to use `asInstanceOf` and you did not try the `extracting` I pointed out, I have updated my answer with some working code. – Joel Costigliola Oct 27 '20 at 09:42
many thanks -> I have tried it and as I mentioned I don't have extracting() which accepts such a parameter. I have checked it once again and it seems I have to update library to the newest version. Unfortunately it will be very difficult, cause I have to update spring-boot dependencies then etc. I will mark it as answer, unfortunately I can't use it because of my version of assertj :( – tillias Oct 27 '20 at 09:45
yes, please make sure that version of assertJ needed for your code to work is specified in answer. Otherwise it will raise the same question in future – tillias Oct 27 '20 at 09:50
It is usually ok to use the latest, 3.18.0 at the time of this reply – Joel Costigliola Oct 27 '20 at 20:31
@tillias assuming you have a maven project and you are at least on java 8, you can add 3.18.0 in your properties section to get the updated artifact without upgrading the spring-boot-dependencies version. It should work with both Spring Boot 1.5.x and 2.x. – Stefano Cordio Nov 21 '20 at 21:48

dj_1993 · Answer 3 · 2021-04-03T18:22:20.200

1

I'd do something like :

assertThatThrownBy(() -> service.doSomething())
    .isInstanceOf(SomeException.class)
    .hasMessageStartingWith("SomeException occurred")
    .isEqualToComparingFieldByField(
        new SomeException("", Sets.newHashSet(1,2,3,4)));

This way you don't have to worry about changing the field name in future because you're not hardcoding it anywhere in the assert statements.

edited Apr 03 '21 at 18:22

answered Apr 02 '21 at 11:49

dj_1993

93
1
8

score 0 · Answer 4 · answered Jan 24 '23 at 09:49

An alternative to the extracting method would be to catch the exception in matches or satisfies method :

var elements = Set.of(1, 2, 3, 4);

assertThat(throwable)
  .isInstanceOf(SomeException.class)
  .hasMessageStartingWith("...")
  .matches(e -> ((SomeException) e).getSomething().containsAll(elements);

assertThat(throwable)
  .isInstanceOf(SomeException.class)
  .hasMessageStartingWith("...")
  .satisfies(e -> {
    SomethingException somethingException = (SomethingException) e;

    assertThat(somethingException.getSomething()).contains(1, 2, 3, 4);
  });

assertThatThrownBy() check field on custom exception

4 Answers4