diff --git a/Part_4/blog-list/tests/mostLikes.test.js b/Part_4/blog-list/tests/mostLikes.test.js
new file mode 100644
index 0000000..6132065
--- /dev/null
+++ b/Part_4/blog-list/tests/mostLikes.test.js
@@ -0,0 +1,84 @@
+const mostLikes = require('../utils/list_helper').mostLikes
+
+describe('Most likes', () => {
+	const emptyList = []
+
+	const listWithOneBlog = [
+		{
+			_id: "5a422a851b54a676234d17f7",
+			title: "React patterns",
+			author: "Michael Chan",
+			url: "https://reactpatterns.com/",
+			likes: 7,
+			__v: 0
+		}
+	]
+	const listWithMultipleBlogs = [
+		{
+			_id: "5a422a851b54a676234d17f7",
+			title: "React patterns",
+			author: "Michael Chan",
+			url: "https://reactpatterns.com/",
+			likes: 7,
+			__v: 0
+		},
+		{
+			_id: "5a422aa71b54a676234d17f8",
+			title: "Go To Statement Considered Harmful",
+			author: "Edsger W. Dijkstra",
+			url: "http://www.u.arizona.edu/~rubinson/copyright_violations/Go_To_Considered_Harmful.html",
+			likes: 5,
+			__v: 0
+		},
+		{
+			_id: "5a422b3a1b54a676234d17f9",
+			title: "Canonical string reduction",
+			author: "Edsger W. Dijkstra",
+			url: "http://www.cs.utexas.edu/~EWD/transcriptions/EWD08xx/EWD808.html",
+			likes: 12,
+			__v: 0
+		},
+		{
+			_id: "5a422b891b54a676234d17fa",
+			title: "First class tests",
+			author: "Robert C. Martin",
+			url: "http://blog.cleancoder.com/uncle-bob/2017/05/05/TestDefinitions.htmll",
+			likes: 10,
+			__v: 0
+		},
+		{
+			_id: "5a422ba71b54a676234d17fb",
+			title: "TDD harms architecture",
+			author: "Robert C. Martin",
+			url: "http://blog.cleancoder.com/uncle-bob/2017/03/03/TDD-Harms-Architecture.html",
+			likes: 0,
+			__v: 0
+		},
+		{
+			_id: "5a422bc61b54a676234d17fc",
+			title: "Type wars",
+			author: "Robert C. Martin",
+			url: "http://blog.cleancoder.com/uncle-bob/2016/05/01/TypeWars.html",
+			likes: 2,
+			__v: 0
+		}
+	]
+
+	test('for emply list, returns an empty object', () => {
+		const result = mostLikes(emptyList)
+
+		expect(result).toEqual({})
+	})
+
+	test('for list with only one blog, returns the details for the same blog', () => {
+		const result = mostLikes(listWithOneBlog)
+
+		expect(result).toEqual({ author: 'Michael Chan', likes: 7 })
+	})
+
+	test('for multiple blogs, return the author and total likes from the blog author with the most likes', () => {
+		const result = mostLikes(listWithMultipleBlogs)
+
+		expect(result).toEqual({ author: 'Edsger W. Dijkstra', likes: 17})
+	})
+})
diff --git a/Part_4/blog-list/utils/list_helper.js b/Part_4/blog-list/utils/list_helper.js
index c0ec2f2..b925df6 100644
--- a/Part_4/blog-list/utils/list_helper.js
+++ b/Part_4/blog-list/utils/list_helper.js
@@ -37,16 +37,36 @@ const mostBlogs = (blogs) => {
 	
 	const authorWithMostBlogs = _.maxBy(_.keys(blogCount), (author) => blogCount[author])
 
-	if (authorWithMostBlogs.length > 1) {
-		return authorWithMostBlogs[0]
+	return authorWithMostBlogs
+}
+
+const mostLikes = (blogs) => {
+	if (blogs.length === 0) {
+		return {}
 	}
 
-	return authorWithMostBlogs
+	const authorLikes = _.reduce(blogs, (result, blog) => {
+		if (!result[blog.author]) {
+			result[blog.author] = 0;
+		}
+		result[blog.author] += blog.likes
+		return result
+	}, {})
+	
+	const authorWithMostLikes = _.maxBy(_.keys(authorLikes), author => authorLikes[author] )
+	
+	const retObj = {
+		author: authorWithMostLikes,
+		likes: authorLikes[authorWithMostLikes]
+	}
+		
+	return retObj
 }
 
 module.exports = {
 	dummy,
 	totalLikes,
 	favBlog,
-	mostBlogs
+	mostBlogs,
+	mostLikes
 }