I have modified the files and tested them with Jest and got a Pass

Author: KKtech06

Sprint-1/implement/dedupe.test.js

@@ -16,13 +16,22 @@ E.g. dedupe([1, 2, 1]) target output: [1, 2]
 // Given an empty array
 // When passed to the dedupe function
 // Then it should return an empty array
-test.todo("given an empty array, it returns an empty array");
+test("given an empty array, it returns an empty array", () => {
+  expect(dedupe([])).toEqual([]);
+});
 
 // Given an array with no duplicates
 // When passed to the dedupe function
 // Then it should return a copy of the original array
+test("given an array with no duplicates, it returns the same array", () => {
+  expect(dedupe([1, 2, 3])).toEqual([1, 2, 3]);
+});
 
 // Given an array with strings or numbers
 // When passed to the dedupe function
 // Then it should remove the duplicate values, preserving the first occurence of each element
+test("removes duplicates and keeps first occurrence", () => {
+    expect(dedupe(['a','a','a','b','b','c'])).toEqual(['a','b','c']);
+    expect(dedupe([5, 1, 1, 2, 3, 2, 5, 8])).toEqual([5, 1, 2, 3, 8]);
+});
 

Sprint-1/implement/max.test.js

@@ -16,29 +16,48 @@ const findMax = require("./max.js");
 // When passed to the max function
 // Then it should return -Infinity
 // Delete this test.todo and replace it with a test.
-test.todo("given an empty array, returns -Infinity");
+test("given an empty array, returns null", () => {
+  expect(findMax([])).toBe(null);
+});
 
 // Given an array with one number
 // When passed to the max function
 // Then it should return that number
+test("given an array with one number , returns that number", () => {
+  expect(findMax([7])).toBe(7);
+});
 
 // Given an array with both positive and negative numbers
 // When passed to the max function
 // Then it should return the largest number overall
+test("given positive and negative numbers, returns the largest number", () => {
+  expect(findMax([-10, 0, 5, -3, 8])).toBe(8);
+});
 
 // Given an array with just negative numbers
 // When passed to the max function
 // Then it should return the closest one to zero
+test("given only negative numbers, returns the largest negative number", () => {
+  expect(findMax([-10, -4, -2, -30])).toBe(-2);
+});
 
 // Given an array with decimal numbers
 // When passed to the max function
 // Then it should return the largest decimal number
+test("given decimal numbers, returns the largest decimal number", () => {
+  expect(findMax([1.2, 3.7, 2.5])).toBe(3.7);
+});
 
 // Given an array with non-number values
 // When passed to the max function
 // Then it should return the max and ignore non-numeric values
+test("ignores non-number values and returns the max", () => {
+  expect(findMax(["hey", 10, "hi", 60, 10])).toBe(60);
+});
 
 // Given an array with only non-number values
 // When passed to the max function
 // Then it should return the least surprising value given how it behaves for all other inputs
-
+test("given only non-number values, returns null", () => {
+  expect(findMax(["hey", "hi", null, undefined, NaN])).toBe(null);
+});

Sprint-1/implement/sum.test.js

@@ -13,25 +13,43 @@ const sum = require("./sum.js");
 // Given an empty array
 // When passed to the sum function
 // Then it should return 0
-test.todo("given an empty array, returns 0")
+test("given an empty array, returns 0", () => {
+  expect(sum([])).toBe(0);
+});
 
 // Given an array with just one number
 // When passed to the sum function
 // Then it should return that number
+test("given an array with one number, returns that number", () => {
+  expect(sum([7])).toBe(7);
+});
 
 // Given an array containing negative numbers
 // When passed to the sum function
 // Then it should still return the correct total sum
+test("given negative numbers, returns the correct total", () => {
+  expect(sum([-10, -3, -2])).toBe(-15);
+});
 
 // Given an array with decimal/float numbers
 // When passed to the sum function
 // Then it should return the correct total sum
+test("given decimal numbers, returns the correct total", () => {
+  expect(sum([1.5, 2.5, 3])).toBe(7);
+});
 
 // Given an array containing non-number values
 // When passed to the sum function
 // Then it should ignore the non-numerical values and return the sum of the numerical elements
+test("ignores non-number values and returns the sum", () => {
+  expect(sum(["hey", 10, "hi", 60, 10])).toBe(80);
+});
+
 
 // Given an array with only non-number values
 // When passed to the sum function
 // Then it should return the least surprising value given how it behaves for all other inputs
+test("given only non-number values, returns 0", () => {
+  expect(sum(["hey", "hi", null, undefined, NaN])).toBe(0);
+});