testing UnitTests define: #ExtensibleArray &parents: {TestCase}.

tc@(UnitTests ExtensibleArray traits) testAtInsert
[| ea1 ea2 |
  ea1: ExtensibleArray new.  
  ea2: ExtensibleArray new.
  0 upTo: 10 do: [| :ind |
    ea1 at: ind insert: ind + 1.
    ea2 add: ind + 1.
    tc assert: ea1 = ea2 description: '#add: and #at:insert differ at: ' ; (ind as: String)].
].

tc@(UnitTests ExtensibleArray traits) suite
[
  tc suiteForSelectors: {
    #testAtInsert
  }
].