heapqueue minor improvement (#16088)

tests/stdlib/theapqueue.nim

@@ -0,0 +1,53 @@
+import heapqueue
+
+
+proc toSortedSeq[T](h: HeapQueue[T]): seq[T] =
+  var tmp = h
+  result = @[]
+  while tmp.len > 0:
+    result.add(pop(tmp))
+
+block: # Simple sanity test
+  var heap = initHeapQueue[int]()
+  let data = [1, 3, 5, 7, 9, 2, 4, 6, 8, 0]
+  for item in data:
+    push(heap, item)
+  doAssert(heap == data.toHeapQueue)
+  doAssert(heap[0] == 0)
+  doAssert(heap.toSortedSeq == @[0, 1, 2, 3, 4, 5, 6, 7, 8, 9])
+
+block: # Test del
+  var heap = initHeapQueue[int]()
+  let data = [1, 3, 5, 7, 9, 2, 4, 6, 8, 0]
+  for item in data: push(heap, item)
+
+  heap.del(0)
+  doAssert(heap[0] == 1)
+
+  heap.del(heap.find(7))
+  doAssert(heap.toSortedSeq == @[1, 2, 3, 4, 5, 6, 8, 9])
+
+  heap.del(heap.find(5))
+  doAssert(heap.toSortedSeq == @[1, 2, 3, 4, 6, 8, 9])
+
+  heap.del(heap.find(6))
+  doAssert(heap.toSortedSeq == @[1, 2, 3, 4, 8, 9])
+
+  heap.del(heap.find(2))
+  doAssert(heap.toSortedSeq == @[1, 3, 4, 8, 9])
+
+  doAssert(heap.find(2) == -1)
+
+block: # Test del last
+  var heap = initHeapQueue[int]()
+  let data = [1, 2, 3]
+  for item in data: push(heap, item)
+
+  heap.del(2)
+  doAssert(heap.toSortedSeq == @[1, 2])
+
+  heap.del(1)
+  doAssert(heap.toSortedSeq == @[1])
+
+  heap.del(0)
+  doAssert(heap.toSortedSeq == @[])