diff --git a/test/unit/data-structures/heap/heap.test.ts b/test/unit/data-structures/heap/heap.test.ts
index 06cb7a9..ac6f4f6 100644
--- a/test/unit/data-structures/heap/heap.test.ts
+++ b/test/unit/data-structures/heap/heap.test.ts
@@ -21,34 +21,42 @@ describe('Heap Operation Test', () => {
   });
 
   it('should object heap work well', function () {
-    const minHeap = new MinHeap<{a: string}>();
-    minHeap.add(1, {a: 'a1'});
-    minHeap.add(6, {a: 'a6'});
-    minHeap.add(2, {a: 'a2'});
-    minHeap.add(0, {a: 'a0'});
+    const minHeap = new MinHeap<{a: string; key: number}>((a, b) => a.key - b.key);
+    minHeap.add({key: 1, a: 'a1'});
+    minHeap.add({key: 6, a: 'a6'});
+    minHeap.add({key: 2, a: 'a2'});
+    minHeap.add({key: 0, a: 'a0'});
 
-    expect(minHeap.peek()).toEqual({a: 'a0'});
-    expect(minHeap.toArray()).toEqual([{a: 'a0'}, {a: 'a1'}, {a: 'a2'}, {a: 'a6'}]);
+    expect(minHeap.peek()).toEqual({a: 'a0', key: 0});
+    console.log('---', minHeap.toArray());
+    expect(minHeap.toArray().map(item => ({a: item.a}))).toEqual([{a: 'a0'}, {a: 'a1'}, {a: 'a2'}, {a: 'a6'}]);
     let i = 0;
     const expectPolled = [{a: 'a0'}, {a: 'a1'}, {a: 'a2'}, {a: 'a6'}];
     while (minHeap.size > 0) {
-      expect(minHeap.poll()).toEqual(expectPolled[i]);
+      expect({a: minHeap.poll()?.a}).toEqual(expectPolled[i]);
       i++;
     }
 
-    const maxHeap = new MaxHeap<{a: string}>();
-    maxHeap.add(1, {a: 'a1'});
-    maxHeap.add(6, {a: 'a6'});
-    maxHeap.add(5, {a: 'a5'});
-    maxHeap.add(2, {a: 'a2'});
-    maxHeap.add(0, {a: 'a0'});
-    maxHeap.add(9, {a: 'a9'});
-    expect(maxHeap.peek()).toEqual({a: 'a9'});
-    expect(maxHeap.toArray()).toEqual([{a: 'a9'}, {a: 'a2'}, {a: 'a6'}, {a: 'a1'}, {a: 'a0'}, {a: 'a5'}]);
+    const maxHeap = new MaxHeap<{key: number; a: string}>((a, b) => b.key - a.key);
+    maxHeap.add({key: 1, a: 'a1'});
+    maxHeap.add({key: 6, a: 'a6'});
+    maxHeap.add({key: 5, a: 'a5'});
+    maxHeap.add({key: 2, a: 'a2'});
+    maxHeap.add({key: 0, a: 'a0'});
+    maxHeap.add({key: 9, a: 'a9'});
+    expect(maxHeap.peek()).toEqual({a: 'a9', key: 9});
+    expect(maxHeap.toArray().map(item => ({a: item.a}))).toEqual([
+      {a: 'a9'},
+      {a: 'a2'},
+      {a: 'a6'},
+      {a: 'a1'},
+      {a: 'a0'},
+      {a: 'a5'}
+    ]);
     const maxExpectPolled = [{a: 'a9'}, {a: 'a6'}, {a: 'a5'}, {a: 'a2'}, {a: 'a1'}, {a: 'a0'}];
     let maxI = 0;
     while (maxHeap.size > 0) {
-      expect(maxHeap.poll()).toEqual(maxExpectPolled[maxI]);
+      expect({a: maxHeap.poll()?.a}).toEqual(maxExpectPolled[maxI]);
       maxI++;
     }
   });
diff --git a/test/unit/data-structures/heap/max-heap.test.ts b/test/unit/data-structures/heap/max-heap.test.ts
index a2f3b50..6b120fb 100644
--- a/test/unit/data-structures/heap/max-heap.test.ts
+++ b/test/unit/data-structures/heap/max-heap.test.ts
@@ -1,44 +1,52 @@
-import {HeapItem, MaxHeap} from '../../../../src';
+import {CompareFunction, MaxHeap} from '../../../../src';
 
-describe('MaxHeap Operation Test', () => {
-  it('should object Max Heap operations be proper', function () {
-    const maxHeap = new MaxHeap<{keyA: string}>();
-    const myObj1 = {keyA: 'a1'},
-      myObj6 = {keyA: 'a6'},
-      myObj5 = {keyA: 'a5'},
-      myObj2 = {keyA: 'a2'},
-      myObj0 = {keyA: 'a0'},
-      myObj9 = {keyA: 'a9'};
-    maxHeap.add(1, myObj1);
-    expect(maxHeap.has(myObj1)).toBe(true);
-    expect(maxHeap.has(myObj9)).toBe(false);
-    maxHeap.add(6, myObj6);
-    expect(maxHeap.has(myObj6)).toBe(true);
-    maxHeap.add(5, myObj5);
-    expect(maxHeap.has(myObj5)).toBe(true);
-    maxHeap.add(2, myObj2);
-    expect(maxHeap.has(myObj2)).toBe(true);
-    expect(maxHeap.has(myObj6)).toBe(true);
-    maxHeap.add(0, myObj0);
-    expect(maxHeap.has(myObj0)).toBe(true);
-    expect(maxHeap.has(myObj9)).toBe(false);
-    maxHeap.add(9, myObj9);
-    expect(maxHeap.has(myObj9)).toBe(true);
+describe('MaxHeap', () => {
+  const numberComparator: CompareFunction<number> = (a, b) => b - a;
+  let maxHeap: MaxHeap<number>;
 
-    const peek9 = maxHeap.peek(true);
-    peek9 && peek9.val && expect(peek9.val.keyA).toBe('a9');
+  beforeEach(() => {
+    maxHeap = new MaxHeap(numberComparator);
+  });
 
-    const heapToArr = maxHeap.toArray(true);
-    expect(heapToArr.map(item => item?.val?.keyA)).toEqual(['a9', 'a2', 'a6', 'a1', 'a0', 'a5']);
+  test('add and poll elements in descending order', () => {
+    maxHeap.add(3);
+    maxHeap.add(1);
+    maxHeap.add(4);
+    maxHeap.add(2);
 
-    const values = ['a9', 'a6', 'a5', 'a2', 'a1', 'a0'];
-    let i = 0;
-    while (maxHeap.size > 0) {
-      const polled = maxHeap.poll(true);
-      expect(polled).toBeInstanceOf(HeapItem);
-      polled && expect(polled.val).toHaveProperty('keyA');
-      polled && polled.val && expect(polled.val.keyA).toBe(values[i]);
-      i++;
-    }
+    expect(maxHeap.poll()).toBe(4);
+    expect(maxHeap.poll()).toBe(3);
+    expect(maxHeap.poll()).toBe(2);
+    expect(maxHeap.poll()).toBe(1);
+  });
+
+  test('peek at the top element without removing it', () => {
+    maxHeap.add(3);
+    maxHeap.add(1);
+    maxHeap.add(4);
+    maxHeap.add(2);
+
+    expect(maxHeap.peek()).toBe(4);
+    expect(maxHeap.size).toBe(4);
+  });
+
+  test('sort elements in descending order', () => {
+    maxHeap.add(3);
+    maxHeap.add(1);
+    maxHeap.add(4);
+    maxHeap.add(2);
+
+    const sortedArray = maxHeap.sort();
+    expect(sortedArray).toEqual([4, 3, 2, 1]);
+  });
+
+  test('check if the heap is empty', () => {
+    expect(maxHeap.isEmpty()).toBe(true);
+
+    maxHeap.add(5);
+    expect(maxHeap.isEmpty()).toBe(false);
+
+    maxHeap.poll();
+    expect(maxHeap.isEmpty()).toBe(true);
   });
 });
diff --git a/test/unit/data-structures/heap/min-heap.test.ts b/test/unit/data-structures/heap/min-heap.test.ts
index 4bef02d..14de30f 100644
--- a/test/unit/data-structures/heap/min-heap.test.ts
+++ b/test/unit/data-structures/heap/min-heap.test.ts
@@ -1,82 +1,52 @@
-import {HeapItem, MinHeap} from '../../../../src';
+import {CompareFunction, MinHeap} from '../../../../src';
 
-describe('MinHeap Operation Test', () => {
-  it('should numeric Min Heap operations be proper', function () {
-    const minNumHeap = new MinHeap<number>();
-    expect(minNumHeap).toBeInstanceOf(MinHeap);
+describe('MinHeap', () => {
+  const numberComparator: CompareFunction<number> = (a, b) => a - b;
+  let minHeap: MinHeap<number>;
 
-    minNumHeap.add(1);
-    expect(minNumHeap.has(1)).toBe(true);
-    minNumHeap.add(6);
-    expect(minNumHeap.has(2)).toBe(false);
-    expect(minNumHeap.has(6)).toBe(true);
-    minNumHeap.add(2);
-    expect(minNumHeap.has(2)).toBe(true);
-    minNumHeap.add(0);
-    expect(minNumHeap.has(0)).toBe(true);
-    minNumHeap.add(5);
-    expect(minNumHeap.has(5)).toBe(true);
-    minNumHeap.add(9);
-    expect(minNumHeap.has(9)).toBe(true);
-    expect(minNumHeap.size).toBe(6);
-
-    const poll1 = minNumHeap.poll(true);
-    expect(poll1).toBeInstanceOf(HeapItem);
-    poll1 instanceof HeapItem && expect(poll1.val).toBe(0);
-
-    const poll2 = minNumHeap.poll(true);
-    expect(poll2).toBeInstanceOf(HeapItem);
-    poll2 instanceof HeapItem && expect(poll2.val).toBe(1);
-
-    const peek1 = minNumHeap.peek(true);
-    expect(peek1).toBeInstanceOf(HeapItem);
-    peek1 instanceof HeapItem && expect(peek1.val).toBe(2);
-
-    const heapArray = minNumHeap.toArray(true);
-    expect(heapArray).toBeInstanceOf(Array);
-    expect(heapArray.map(item => item?.priority)).toEqual([2, 5, 9, 6]);
-    expect(minNumHeap.size).toBe(4);
+  beforeEach(() => {
+    minHeap = new MinHeap(numberComparator);
   });
 
-  it('should object Min Heap operations be proper', function () {
-    class MyObject {
-      keyA: string;
+  test('add and poll elements in ascending order', () => {
+    minHeap.add(3);
+    minHeap.add(1);
+    minHeap.add(4);
+    minHeap.add(2);
 
-      constructor(keyA: string) {
-        this.keyA = keyA;
-      }
-    }
+    expect(minHeap.poll()).toBe(1);
+    expect(minHeap.poll()).toBe(2);
+    expect(minHeap.poll()).toBe(3);
+    expect(minHeap.poll()).toBe(4);
+  });
 
-    const minObjHeap = new MinHeap<MyObject>();
+  test('peek at the top element without removing it', () => {
+    minHeap.add(3);
+    minHeap.add(1);
+    minHeap.add(4);
+    minHeap.add(2);
 
-    const obj1 = new MyObject('a1'),
-      obj6 = new MyObject('a6'),
-      obj2 = new MyObject('a2'),
-      obj0 = new MyObject('a0');
-    minObjHeap.add(1, obj1);
-    expect(minObjHeap.has(obj1)).toBe(true);
-    expect(minObjHeap.has(obj6)).toBe(false);
-    minObjHeap.add(6, obj6);
-    expect(minObjHeap.has(obj6)).toBe(true);
-    minObjHeap.add(2, obj2);
-    expect(minObjHeap.has(obj2)).toBe(true);
-    minObjHeap.add(0, obj0);
-    expect(minObjHeap.has(obj0)).toBe(true);
+    expect(minHeap.peek()).toBe(1);
+    expect(minHeap.size).toBe(4);
+  });
 
-    const peek = minObjHeap.peek(true);
-    peek && peek.val && expect(peek.val.keyA).toBe('a0');
+  test('sort elements in ascending order', () => {
+    minHeap.add(3);
+    minHeap.add(1);
+    minHeap.add(4);
+    minHeap.add(2);
 
-    const heapToArr = minObjHeap.toArray(true);
-    expect(heapToArr.map(item => item?.val?.keyA)).toEqual(['a0', 'a1', 'a2', 'a6']);
+    const sortedArray = minHeap.sort();
+    expect(sortedArray).toEqual([1, 2, 3, 4]);
+  });
 
-    const values = ['a0', 'a1', 'a2', 'a6'];
-    let i = 0;
-    while (minObjHeap.size > 0) {
-      const polled = minObjHeap.poll(true);
-      expect(polled).toBeInstanceOf(HeapItem);
-      polled && expect(polled.val).toBeInstanceOf(MyObject);
-      polled && polled.val && expect(polled.val.keyA).toBe(values[i]);
-      i++;
-    }
+  test('check if the heap is empty', () => {
+    expect(minHeap.isEmpty()).toBe(true);
+
+    minHeap.add(5);
+    expect(minHeap.isEmpty()).toBe(false);
+
+    minHeap.poll();
+    expect(minHeap.isEmpty()).toBe(true);
   });
 });
diff --git a/test/unit/data-structures/priority-queue/max-priority-queue.test.ts b/test/unit/data-structures/priority-queue/max-priority-queue.test.ts
index 60da9db..ac39ea2 100644
--- a/test/unit/data-structures/priority-queue/max-priority-queue.test.ts
+++ b/test/unit/data-structures/priority-queue/max-priority-queue.test.ts
@@ -17,11 +17,8 @@ describe('MaxPriorityQueue Operation Test', () => {
   });
 
   it('should add elements and maintain heap property in a object MaxPriorityQueue', () => {
-    const priorityQueue = new MaxPriorityQueue<{keyA: number}>({
-      nodes: [{keyA: 5}, {keyA: 3}, {keyA: 1}],
-      comparator: (a, b) => b.keyA - a.keyA
-    });
-
+    const priorityQueue = new MaxPriorityQueue<{keyA: number}>((a, b) => b.keyA - a.keyA);
+    priorityQueue.refill([{keyA: 5}, {keyA: 3}, {keyA: 1}]);
     priorityQueue.add({keyA: 7});
 
     expect(priorityQueue.poll()?.keyA).toBe(7);
@@ -56,7 +53,8 @@ describe('MaxPriorityQueue Operation Test', () => {
 
   it('should correctly heapify an array', () => {
     const array = [5, 3, 7, 1];
-    const heap = MaxPriorityQueue.heapify<number>({nodes: array});
+    const heap = MaxPriorityQueue.heapify<number>(array, (a, b) => b - a);
+    heap.refill(array);
 
     expect(heap.poll()).toBe(7);
     expect(heap.poll()).toBe(5);
@@ -66,7 +64,7 @@ describe('MaxPriorityQueue Operation Test', () => {
 
   it('should correctly heapify an object array', () => {
     const nodes = [{keyA: 5}, {keyA: 3}, {keyA: 7}, {keyA: 1}];
-    const maxPQ = MaxPriorityQueue.heapify<{keyA: number}>({nodes, comparator: (a, b) => b.keyA - a.keyA});
+    const maxPQ = MaxPriorityQueue.heapify<{keyA: number}>(nodes, (a, b) => b.keyA - a.keyA);
 
     expect(maxPQ.poll()?.keyA).toBe(7);
     expect(maxPQ.poll()?.keyA).toBe(5);
@@ -81,8 +79,8 @@ describe('MaxPriorityQueue Performance Test', () => {
       new Set<number>(Array.from(new Array(magnitude.LINEAR), () => Math.floor(Math.random() * magnitude.LINEAR * 100)))
     );
     expect(nodes.length).toBeGreaterThan(magnitude.LINEAR / 2);
-    const maxPQ = new MaxPriorityQueue<number>({nodes});
-
+    const maxPQ = new MaxPriorityQueue<number>();
+    maxPQ.refill(nodes);
     let prev = Number.MAX_SAFE_INTEGER;
     const startTime = performance.now();
     while (maxPQ.size > 0) {
diff --git a/test/unit/data-structures/priority-queue/priority-queue.test.ts b/test/unit/data-structures/priority-queue/priority-queue.test.ts
index e25e208..29bcd87 100644
--- a/test/unit/data-structures/priority-queue/priority-queue.test.ts
+++ b/test/unit/data-structures/priority-queue/priority-queue.test.ts
@@ -2,54 +2,37 @@ import {PriorityQueue} from '../../../../src';
 import {getRandomInt} from '../../../utils';
 
 describe('PriorityQueue Operation Test', () => {
-  it('should validate a priority queue', () => {
-    const minPQ = new PriorityQueue<number>({nodes: [1, 5, 7, 9, 3, 6, 2], comparator: (a, b) => a - b});
-
-    expect(minPQ.isValid()).toBe(true);
-    expect(PriorityQueue.isPriorityQueueified({nodes: minPQ.nodes, comparator: (a, b) => a - b})).toBe(true);
-    expect(PriorityQueue.isPriorityQueueified({nodes: minPQ.nodes, comparator: (a, b) => b - a})).toBe(false);
-    expect(
-      PriorityQueue.isPriorityQueueified({
-        nodes: [1, 5, 7, 9, 3, 6, 2],
-        comparator: (a, b) => b - a
-      })
-    ).toBe(false);
-  });
-
   it('should PriorityQueue poll, pee, heapify, toArray work well', function () {
-    const minPQ = new PriorityQueue<number>({nodes: [5, 2, 3, 4, 6, 1], comparator: (a, b) => a - b});
+    const minPQ = new PriorityQueue<number>((a, b) => a - b);
+    minPQ.refill([5, 2, 3, 4, 6, 1]);
     expect(minPQ.toArray()).toEqual([1, 2, 3, 4, 6, 5]);
     minPQ.poll();
     minPQ.poll();
     minPQ.poll();
     expect(minPQ.toArray()).toEqual([4, 5, 6]);
     expect(minPQ.peek()).toBe(4);
-    expect(
-      PriorityQueue.heapify({
-        nodes: [3, 2, 1, 5, 6, 7, 8, 9, 10],
-        comparator: (a, b) => a - b
-      }).toArray()
-    ).toEqual([1, 2, 3, 5, 6, 7, 8, 9, 10]);
+    expect(PriorityQueue.heapify([3, 2, 1, 5, 6, 7, 8, 9, 10], (a, b) => a - b).toArray()).toEqual([
+      1, 2, 3, 5, 6, 7, 8, 9, 10
+    ]);
   });
 
   it('should Max PriorityQueue poll, peek, heapify, toArray work well', function () {
-    const maxPriorityQueue = new PriorityQueue<number>({nodes: [5, 2, 3, 4, 6, 1], comparator: (a, b) => b - a});
+    const maxPriorityQueue = new PriorityQueue<number>((a, b) => b - a);
+    maxPriorityQueue.refill([5, 2, 3, 4, 6, 1]);
     expect(maxPriorityQueue.toArray()).toEqual([6, 5, 3, 4, 2, 1]);
     maxPriorityQueue.poll();
     maxPriorityQueue.poll();
     maxPriorityQueue.poll();
     expect(maxPriorityQueue.toArray()).toEqual([3, 2, 1]);
     expect(maxPriorityQueue.peek()).toBe(3);
-    expect(
-      PriorityQueue.heapify({
-        nodes: [3, 2, 1, 5, 6, 7, 8, 9, 10],
-        comparator: (a, b) => a - b
-      }).toArray()
-    ).toEqual([1, 2, 3, 5, 6, 7, 8, 9, 10]);
+    expect(PriorityQueue.heapify([3, 2, 1, 5, 6, 7, 8, 9, 10], (a, b) => a - b).toArray()).toEqual([
+      1, 2, 3, 5, 6, 7, 8, 9, 10
+    ]);
   });
 
   it('should PriorityQueue clone, sort, getNodes, dfs work well', function () {
-    const minPQ1 = new PriorityQueue<number>({nodes: [2, 5, 8, 3, 1, 6, 7, 4], comparator: (a, b) => a - b});
+    const minPQ1 = new PriorityQueue<number>((a, b) => a - b);
+    minPQ1.refill([2, 5, 8, 3, 1, 6, 7, 4]);
     const clonedPriorityQueue = minPQ1.clone();
     expect(clonedPriorityQueue.getNodes()).toEqual(minPQ1.getNodes());
     expect(clonedPriorityQueue.sort()).toEqual([1, 2, 3, 4, 5, 6, 7, 8]);
@@ -62,7 +45,8 @@ describe('PriorityQueue Operation Test', () => {
 describe('Priority Queue Performance Test', () => {
   it('should numeric heap work well', function () {
     const values = Array.from(new Array(10000), () => getRandomInt(1, 10000000));
-    const minPriorityQueue = new PriorityQueue<number>({nodes: values, comparator: (a, b) => a - b});
+    const minPriorityQueue = new PriorityQueue<number>((a, b) => a - b);
+    minPriorityQueue.refill(values);
     const sorted = minPriorityQueue.sort();
     expect(sorted).toEqual(values.sort((a, b) => a - b));
   });