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

Answer 1

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);

Answer 2

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();