Merge pull request knaxus#46 from DaniloBarros/add-test-to-loop-in-list

Add unit test to loop-in-list

Author: ashokdey

src/_DataStructures_/LinkedList/loop-in-list/index.js

@@ -1,6 +1,6 @@
 // Floyd’s Cycle-Finding Algorithm
 
-function detechLoop(linkedList) {
+function detectLoop(linkedList) {
   let slow = linkedList.getFirst();
   let fast = linkedList.getFirst();
 
@@ -14,3 +14,7 @@ function detechLoop(linkedList) {
   }
   return false;
 }
+
+module.exports = {
+  detectLoop,
+};

src/_DataStructures_/LinkedList/loop-in-list/loop-in-list.test.js

@@ -0,0 +1,40 @@
+const { LinkedList } = require('../index');
+const { detectLoop } = require('.');
+
+describe('Loop a LinkedList', () => {
+  let loopList = null;
+  let last = null;
+  beforeEach(() => {
+    loopList = new LinkedList();
+    loopList.addAtBeginning('1');
+    loopList.addAtEnd('2');
+    loopList.addAtEnd('3');
+    loopList.addAtEnd('4');
+    loopList.addAtEnd('5');
+    // Create loop in list
+    last = loopList.getLast();
+    last.next = loopList.getFirst();
+  });
+
+  it('Should break for empty list', () => {
+    loopList.delete();
+    expect(() => detectLoop(loopList)).toThrow(TypeError);
+  });
+
+  it('Should return `true` when looping list', () => {
+    expect(detectLoop(loopList)).toEqual(true);
+  });
+
+  it('Should return `false` for non loop list', () => {
+    last.next = null; // remove loop in list
+    expect(detectLoop(loopList)).toEqual(false);
+  });
+
+  it('Should return `false` for non loop list', () => {
+    const list = new LinkedList();
+    list.addAtBeginning('1');
+    list.addAtEnd('1');
+    list.addAtEnd('1');
+    expect(detectLoop(list)).toEqual(false);
+  });
+});