fix: improve mean function with input validation and extended tests (#1785)

Author: FatihBARACKILIC

Maths/AverageMean.js

@@ -1,19 +1,30 @@
 /**
  * @function mean
  * @description This script will find the mean value of a array of numbers.
- * @param {Integer[]} nums - Array of integer
- * @return {Integer} - mean of nums.
+ * @param {number[]} numbers - Array of integer
+ * @return {number} - mean of numbers.
+ * @throws {TypeError} If the input is not an array or contains non-number elements.
+ * @throws {Error} If the input array is empty.
  * @see [Mean](https://en.wikipedia.org/wiki/Mean)
  * @example mean([1, 2, 4, 5]) = 3
  * @example mean([10, 40, 100, 20]) = 42.5
  */
-
-const mean = (nums) => {
-  if (!Array.isArray(nums)) {
+const mean = (numbers) => {
+  if (!Array.isArray(numbers)) {
     throw new TypeError('Invalid Input')
+  } else if (numbers.length === 0) {
+    throw new Error('Array is empty')
   }
 
-  return nums.reduce((sum, cur) => sum + cur, 0) / nums.length
+  let total = 0
+  numbers.forEach((num) => {
+    if (typeof num !== 'number') {
+      throw new TypeError('Invalid Input')
+    }
+    total += num
+  })
+
+  return total / numbers.length
 }
 
 export { mean }

Maths/test/AverageMean.test.js

@@ -18,4 +18,50 @@ describe('Tests for average mean', () => {
     const meanFunction = mean([10, 40, 100, 20])
     expect(meanFunction).toBe(42.5)
   })
+
+  it('should return the number itself for a single-element array', () => {
+    const result = mean([5])
+    expect(result).toBe(5)
+  })
+
+  it('should throw error for empty array', () => {
+    expect(() => mean([])).toThrow()
+  })
+
+  it('should throw error for an array containing null', () => {
+    expect(() => mean([1, 2, null])).toThrow()
+  })
+
+  it('should throw error for an array containing booleans', () => {
+    expect(() => mean([1, 2, true])).toThrow()
+  })
+
+  it('should throw error for an array containing strings', () => {
+    expect(() => mean([1, 2, 'asd'])).toThrow()
+  })
+
+  it('should return the mean of an array with negative numbers', () => {
+    const result = mean([-1, -2, -3, -4])
+    expect(result).toBe(-2.5)
+  })
+
+  it('should return the mean of an array with floating-point numbers', () => {
+    const result = mean([1.5, 2.5, 3.5])
+    expect(result).toBe(2.5)
+  })
+
+  it('should return 0 for an array with zeros', () => {
+    const result = mean([0, 0, 0])
+    expect(result).toBe(0)
+  })
+
+  it('should handle very large numbers correctly', () => {
+    const result = mean([1000000000, 2000000000, 3000000000])
+    expect(result).toBe(2000000000)
+  })
+
+  it('should return correct mean for an array with integers and floating-point numbers', () => {
+    const result = mean([1, 2.5, 3])
+    expect(result).toBeCloseTo(2.1667, 4)
+  })
 })