add fizzbuzz function and corresponding tests

Author: rahanasuleiman8-ship-it

test-driven-development/fizzbuzz.js

@@ -0,0 +1,10 @@
+function fizzbuzz(number){
+  if (number % 3 === 0 && number % 5 === 0){
+    return "fizzbuzz";
+  } else if (number % 5 === 0){
+    return "buzz";
+  } else if (number % 3 === 0){
+    return "fizz";
+  }
+  return number.toString();
+};

test-driven-development/fizzbuzz.test.js

@@ -0,0 +1,36 @@
+import {fizzbuzz} from './fizzbuzz.js';
+import assert from 'node:assert';
+import {test, describe} from 'node:test';
+
+describe('division by 3 and 5', () => { 
+
+    test('15 returns fizzbuzz', () => {
+        assert.equal(fizzbuzz(15), "fizzbuzz");
+    });
+
+    test('30 returns fizzbuzz', () => {
+        assert.equal(fizzbuzz(30), "fizzbuzz");
+    });
+
+    test('90 returns fizzbuzz', () => {
+        assert.equal(fizzbuzz(90), "fizzbuzz");
+    });
+
+});
+
+
+describe('returning the number as a string', () => { 
+
+    test('1 returns "1"', () => {
+        assert.equal(fizzbuzz(1), "1");
+    });
+
+    test('4 returns "4"', () => {
+        assert.equal(fizzbuzz(4), "4");
+    });
+
+    test('91 returns "91"', () => {
+        assert.equal(fizzbuzz(91), "91");
+    });
+
+});