Add tests for splitInteger function

splitInteger.js

@@ -0,0 +1,11 @@
+function splitInteger(value, numberOfParts) {
+  const base = Math.floor(value / numberOfParts);
+  const remainder = value % numberOfParts;
+  const result = Array(numberOfParts).fill(base);
+  for (let i = 0; i < remainder; i++) {
+    result[numberOfParts - 1 - i]++;
+  }
+  return result.sort((a, b) => a - b);
+}
+
+module.exports = splitInteger;

src/splitInteger.test.js

@@ -2,20 +2,68 @@
 
 const splitInteger = require('./splitInteger');
 
-test(`should split a number into equal parts
-  if a value is divisible by a numberOfParts`, () => {
+test(
+  'should split a number into equal parts if value is divisible by ' +
+  'numberOfParts',
+  () => {
+    expect(splitInteger(6, 3)).toEqual([2, 2, 2]);
+    expect(splitInteger(12, 4)).toEqual([3, 3, 3, 3]);
+  }
+);
 
-});
+test(
+  'should return a part equal to value when splitting into 1 part',
+  () => {
+    expect(splitInteger(8, 1)).toEqual([8]);
+    expect(splitInteger(123, 1)).toEqual([123]);
+  }
+);
 
-test(`should return a part equals to a value
-  when splitting into 1 part`, () => {
+test('should sort parts ascending if they are not equal', () => {
+  const result = splitInteger(17, 4);
+  expect(result).toEqual([4, 4, 4, 5]);
+  expect(result).toEqual([...result].sort((a, b) => a - b));
+});
 
+test('should add zeros if value < numberOfParts', () => {
+  expect(splitInteger(3, 5)).toEqual([0, 0, 1, 1, 1]);
+  expect(splitInteger(0, 3)).toEqual([0, 0, 0]);
+  expect(splitInteger(1, 4)).toEqual([0, 0, 0, 1]);
 });
 
-test('should sort parts ascending if they are not equal', () => {
+test('should ensure the sum of parts equals the original value', () => {
+  const testCases = [
+    [8, 1],
+    [6, 2],
+    [17, 4],
+    [32, 6],
+    [0, 3],
+    [3, 5],
+    [1, 4],
+    [100, 9],
+  ];
 
+  for (const [value, parts] of testCases) {
+    const result = splitInteger(value, parts);
+    const sum = result.reduce((a, b) => a + b, 0);
+    expect(sum).toBe(value);
+  }
 });
 
-test('should add zeros if value < numberOfParts', () => {
+test('should ensure the difference between max and min is at most 1', () => {
+  const testCases = [
+    [17, 4],
+    [32, 6],
+    [3, 5],
+    [0, 3],
+    [1, 4],
+    [100, 9],
+  ];
 
+  for (const [value, parts] of testCases) {
+    const result = splitInteger(value, parts);
+    const min = Math.min(...result);
+    const max = Math.max(...result);
+    expect(max - min).toBeLessThanOrEqual(1);
+  }
 });