update: added unit tests

Author: ashokdey

src/_DataStructures_/Heaps/MaxHeap/MaxHeap.test.js

@@ -0,0 +1,50 @@
+const MaxHeap = require('.');
+
+describe('MaxHeap', () => {
+  it('Should be a class', () => {
+    expect(typeof MaxHeap.prototype.constructor).toEqual('function');
+  });
+
+  it('Should create an instance of MaxHeap', () => {
+    const mh = new MaxHeap();
+    expect(mh instanceof MaxHeap).toEqual(true);
+  });
+
+  it('Should add an element to the MaxHeap', () => {
+    const mh = new MaxHeap();
+    mh.add(10);
+    expect(mh.getMax()).toEqual(10);
+  });
+
+  it('Should keep the largest element at the root', () => {
+    const mh = new MaxHeap();
+    [12, 5, 34].forEach(el => mh.add(el));
+    expect(mh.getMax()).toEqual(34);
+  });
+
+  it('Should retain Heap properties after removal of an element', () => {
+    const mh = new MaxHeap();
+    [12, 45, 1, 34].forEach(el => mh.add(el));
+    expect(mh.getMax()).toEqual(45);
+    mh.remove();
+    expect(mh.getMax()).toEqual(34);
+  });
+
+  it('Should return `null` when heap is empty', () => {
+    const mh = new MaxHeap();
+    [1, 34].forEach(el => mh.add(el));
+    expect(mh.getMax()).toEqual(34);
+    mh.remove();
+    mh.remove();
+    expect(mh.getMax()).toEqual(null);
+  });
+
+  it('Should return the elelment value on `remove()`', () => {
+    const mh = new MaxHeap();
+    [1, 34].forEach(el => mh.add(el));
+    expect(mh.getMax()).toEqual(34);
+    expect(mh.remove()).toEqual(34);
+    expect(mh.remove()).toEqual(1);
+    expect(mh.getMax()).toEqual(null);
+  });
+});