template testing

server/__tests__/utils/time.tests.js

@@ -0,0 +1,16 @@
+import { stringFromMillis } from '../../src/utils/time';
+
+const t1 = { val: null, result: '...' };
+test('test stringFromMillis() on null values', () => {
+  expect(stringFromMillis(t1.val)).toBe(t1.result);
+});
+
+const t2 = { val: 3600000, result: '01:00:00' };
+test('test stringFromMillis() on valid millis', () => {
+  expect(stringFromMillis(t2.val)).toBe(t2.result);
+});
+
+const t3 = { val: -3600000, result: '-01:00:00' };
+test('test stringFromMillis() on negative millis', () => {
+  expect(stringFromMillis(t3.val)).toBe(t3.result);
+});

server/package.json

@@ -16,6 +16,10 @@
     "socket.io": "^4.0.0"
   },
   "scripts": {
-    "start": "node src/app.js"
+    "start": "node src/app.js",
+    "test": "node --experimental-vm-modules node_modules/jest/bin/jest.js"
+  },
+  "devDependencies": {
+    "jest": "^27.0.4"
   }
 }

server/src/utils/time.js

@@ -1,3 +1,12 @@
+/**
+ * @description Converts milliseconds to string representing time
+ * @param {number} ms - time in milliseconds
+ * @param {boolean} showSeconds - wether to show the seconds
+ * @param {string} delim - character between HH MM SS
+ * @param {string} ifNull - what to return if value is null
+ * @returns {string} String representing time 00:12:02
+ */
+
 export const stringFromMillis = (
   ms,
   showSeconds = true,
@@ -5,14 +14,17 @@ export const stringFromMillis = (
   ifNull = '...'
 ) => {
   if (ms === null || isNaN(ms)) return ifNull;
+  const isNegative = ms < 0 ? '-' : '';
+  const millis = Math.abs(ms);
+
   const showWith0 = (value) => (value < 10 ? `0${value}` : value);
-  const hours = showWith0(Math.floor(((ms / (1000 * 60 * 60)) % 60) % 24));
+  const hours = showWith0(Math.floor(((millis / (1000 * 60 * 60)) % 60) % 24));
-  const minutes = showWith0(Math.floor((ms / (1000 * 60)) % 60));
+  const minutes = showWith0(Math.floor((millis / (1000 * 60)) % 60));
-  const seconds = showWith0(Math.floor((ms / 1000) % 60));
+  const seconds = showWith0(Math.floor((millis / 1000) % 60));
 
   return showSeconds
-    ? `${
+    ? `${isNegative}${
         parseInt(hours) ? `${hours}${delim}` : `00${delim}`
       }${minutes}${delim}${seconds}`
-    : `${parseInt(hours) ? `${hours}` : '00'}${delim}${minutes}`;
+    : `${isNegative}${parseInt(hours) ? `${hours}` : '00'}${delim}${minutes}`;
 };