在 usingRecursiveComparison() 的上下文中列出差异

Question

This is an AssertJ specific question. Consider the tests below where two lists are compared first directly and then nested in some other object through usingRecursiveComparison() .

public class RecursiveComparisonWithNestedListsTest {
    @Test
    void topLevelList() {
        assertThat(List.of("Bob", "Chris"))
                .containsExactlyElementsOf(List.of("Bob"));
    }
    @Test
    void nestedList() {
        assertThat(new Person("Amy", List.of("Bob", "Chris")))
                .usingRecursiveComparison()
                .isEqualTo(new Person("Amy", List.of("Bob")));
    }
}
record Person(String name, List<String> friends) {
}

In the first case the message is more helpful, specifying the missing element:

Expecting actual:
  ["Bob", "Chris"]
to contain exactly (and in same order):
  ["Bob"]
but some elements were not expected:
  ["Chris"]

In the second case the message just mentions that the size differs:

Expecting actual:
  Person[name=Amy, friends=[Bob, Chris]]
to be equal to:
  Person[name=Amy, friends=[Bob]]
when recursively comparing field by field, but found the following difference:

field/property 'friends' differ:
- actual value  : ["Bob", "Chris"]
- expected value: ["Bob"]
actual and expected values are collections of different size, actual size=2 when expected size=1

This is just a simple example; the actual use case involves more complex objects and much larger lists. In that context, specifying what item is missing from the list makes a big difference. This brings me to my question: Is there any way to configure the recursive comparison to compare lists just like in the first example?

I certainly have the workaround to ignore the list in the recursive comparison and then assert list equality separately, but I was wondering if there's some trick to get it all in one step.

Answer 1

No there is no such capability at the moment.