t.Fatalf("heap update failed, expected %d as heap min: %s", -21, heapDebugString(heap))
	}

	// Update the minimum element to be smaller. There should be no change.
	heap[0].ev.time = -22
	heapUpdate(heap, 0)
	checkHeap(t, heap)
	if heap[0].ev.time != -22 {
		t.Fatalf("heap update failed, expected %d as heap min: %s", -22, heapDebugString(heap))
	}

	// Update the last element to be larger. There should be no change.