abstract fun <T> collectForComposition(maybeSubject: Option<T>, assertionCreator: Expect<T>.() -> Unit): List<Assertion>
Use this function if you want to collect Assertions and use it as part of an AssertionGroup.
maybeSubject - Either Some wrapping the subject of the current assertion or
None in case a previous subject change was not successful - used as subject for the given assertionCreator.
assertionCreator - A lambda which defines the assertions for the feature.
IllegalArgumentException - in case the given assertionCreator did not create a single
assertion.
Return
The collected assertions as a List<[Assertion]>.