Better testing framework, examples added as tests

idea/testData/psi/examples/Queue.jet

@@ -0,0 +1,33 @@
+class Queue<T> : IPushPop<T> {
+  private class Item<T>(val data : T, var next : Item<T>)
+
+  private var head : Item<T> = null
+  private var tail : Item<T> = null
+
+  override fun push(item : T) {
+    val i = new Item(item)
+    if (tail == null) {
+      head = i
+      tail = head
+    } else {
+      tail.next = i
+      tail = i
+    }
+  }
+
+  override fun pop() =
+    if (head == null)
+      throw new UnderflowException()
+    else {
+      val result = head.data
+      head = head.next
+      if (head == null)
+        tail = null
+      result
+    }
+
+  override val isEmpty
+    get() = head == null
+
+
+}