Fix issue trekhleb#315.

Author: trekhleb

src/data-structures/priority-queue/__test__/PriorityQueue.test.js

@@ -51,14 +51,16 @@ describe('PriorityQueue', () =>{
 expect(priorityQueue.poll()).toBe(5);
 });
 
-it('should be possible to change priority of internal nodes',()=>{
+it('should be possible to change priority of head node',()=>{
 constpriorityQueue=newPriorityQueue();
 
 priorityQueue.add(10,1);
 priorityQueue.add(5,2);
 priorityQueue.add(100,0);
 priorityQueue.add(200,0);
 
+expect(priorityQueue.peek()).toBe(100);
+
 priorityQueue.changePriority(100,10);
 priorityQueue.changePriority(10,20);
 
@@ -68,14 +70,16 @@ describe('PriorityQueue', () =>{
 expect(priorityQueue.poll()).toBe(10);
 });
 
-it('should be possible to change priority of head node',()=>{
+it('should be possible to change priority of internal nodes',()=>{
 constpriorityQueue=newPriorityQueue();
 
 priorityQueue.add(10,1);
 priorityQueue.add(5,2);
 priorityQueue.add(100,0);
 priorityQueue.add(200,0);
 
+expect(priorityQueue.peek()).toBe(100);
+
 priorityQueue.changePriority(200,10);
 priorityQueue.changePriority(10,20);