test if a collection has exactly one element matching a predicate

Question

With Assertj, I can use anyMatch to test if a collection has at least one element matching a predicate, e.g.

var list = List.of("abc", "xyz")
assertThat(list).anyMatch(element -> element.endsWith("xyz"));

But how do I test if a collection has exactly one element that matches a predicate?

Answer 1

How about using the filter? https://github.com/assertj/assertj-core/blob/9eceff23e5b019af3d09c3e9bbc58126d51c02b6/src/main/java/org/assertj/core/api/AbstractIterableAssert.java#L3283

var list = List.of("a", "b", "c!");

assertThat(list)
    .filteredOn(element -> element.endsWith("!"))
    .hasSize(1);