Unit test after upgrading the Spring Boot version hasOnlyOneElementSatisfying() method is not working

Question

Unit test was working fine in its previous version while after updating the version it shows error

public class PersonSearchUtil {
    private final HashSet<SearchResponse> result = new HashSet<>();
    .
    .
    .
    public HashSet<SearchResponse> getResult() {
            return result;
    }
}

Test Method

@Test
fun `When person id is all zeroes, should merge`() {
    val uuid = UUID.randomUUID()
    add() {
        eeId = "same eeId"
        personId = UUID(0,0)
    }
    add() {
        eeId = "same eeId"
        personId = uuid
    }

    assertThat(service.result)
            .hasSize(1)
            .hasOnlyOneElementSatisfying { response ->.  // hasOnlyOneElementSatisfying is deprecated 
                assertThat(response.eeId).isEqualTo("same eeId")  // shows Unresolved reference: eeId 
                assertThat(response.personId).isEqualTo(uuid)  // shows Unresolved reference: personId
            }
}

Error:

Unresolved reference: eeId

Unresolved reference: personId

Answer 1

As mentioned in the javadoc, singleElement() should be used instead.

Also, there is a known issue with Kotlin and recent versions of AssertJ (assertj/assertj-core#2439).

One of the following workarounds might solve your issue until that gets addressed in AssertJ:

assertThat(service.result as Iterable<SearchResponse>)
    .hasSize(1)
    .hasOnlyOneElementSatisfying { response ->
        assertThat(response.eeId).isEqualTo("same eeId")
        assertThat(response.personId).isEqualTo(uuid)
    }
}

CollectionAssert(service.result)
    .hasSize(1)
    .hasOnlyOneElementSatisfying { response ->
        assertThat(response.eeId).isEqualTo("same eeId")
        assertThat(response.personId).isEqualTo(uuid)
    }
}