fun <E : Any, T : Iterable<E?>> Expect<T>.all(assertionCreatorOrNull: (Expect<E>.() -> Unit)?): Expect<T> (source)
Expects that the subject of this expectation (an Iterable) has at least one element and
that either every element holds all assertions created by the assertionCreatorOrNull or
that all elements are null in case assertionCreatorOrNull is defined as null.
Return
an Expect for the subject of this expectation.