update: test cases, prettier rc file for cross IDE code format

Author: ashokdey

.prettierrc.js

@@ -0,0 +1,7 @@
+module.exports = {
+  semi: true,
+  trailingComma: "all",
+  singleQuote: true,
+  printWidth: 120,
+  tabWidth: 2
+};

src/_Problems_/compose-largest-number/compose-largest.test.js

@@ -0,0 +1,34 @@
+const { composeHighest, compare } = require('.');
+
+/**
+ * Test cases
+ * [3, 6, 0, 9] -> 9630
+ * [60, 548] -> 60548
+ * [1, 34, 3, 98, 9, 76, 45, 4] -> 998764543431
+ */
+
+describe('Compose Largest Number', () => {
+  describe('The main function returning the Highest NUmber', () => {
+    it('Should return 9630 for `[3, 6, 0, 9]`', () => {
+      expect(composeHighest([3, 6, 0, 9])).toEqual(9630);
+    });
+
+    it('Should return 60548 for `[60, 548]`', () => {
+      expect(composeHighest([60, 548])).toEqual(60548);
+    });
+
+    it('Should return 998764543431 for `[1, 34, 3, 98, 9, 76, 45, 4]`', () => {
+      expect(composeHighest([1, 34, 3, 98, 9, 76, 45, 4])).toEqual(998764543431);
+    });
+  });
+
+  describe('Testing `compare()`', () => {
+    it('Should return [60, 548] instead of [548, 60]', () => {
+      expect([60, 548].sort(compare)).toEqual([60, 548]);
+    });
+
+    it('Should return [9, 81, 548] instead of [548, 81, 9]', () => {
+      expect([548, 9, 81].sort(compare)).toEqual([9, 81, 548]);
+    });
+  });
+});

src/_Problems_/compose-largest-number/index.js

@@ -8,7 +8,7 @@
  */
 
 /** At first glance, the below solution may seem the answer */
-const hightestNumber = Number([60, 548].sort((a, b) => b - a).join(""));
+// const hightestNumber = Number([60, 548].sort((a, b) => b - a).join(''));
 
 /** The above will fail for test case 2 & 3 */
 
@@ -22,14 +22,16 @@ function compare(a, b) {
 /** final function */
 function composeHighest(arr) {
   if (!arr || !Array.isArray(arr)) {
-    throw new Error("Invalid array/missing argument");
+    throw new Error('Invalid array/missing argument');
   }
 
-  return Number(arr.sort(compare).join(""));
+  return Number(arr.sort(compare).join(''));
 }
 
 /** tests */
 
-console.log(composeHighest([3, 6, 0, 9]) === 9630);
-console.log(composeHighest([60, 548]) === 60548);
-console.log(composeHighest([1, 34, 3, 98, 9, 76, 45, 4]) === 998764543431);
+// console.log(composeHighest([3, 6, 0, 9]) === 9630);
+// console.log(composeHighest([60, 548]) === 60548);
+// console.log(composeHighest([1, 34, 3, 98, 9, 76, 45, 4]) === 998764543431);
+
+module.exports = { composeHighest, compare };