London | 26-ITP-Jan | Oussama Mouggal | Sprint 1| Data-Groups

Sprint-1/fix/median.js

@@ -6,9 +6,25 @@
 // or 'list' has mixed values (the function is expected to sort only numbers).
 
 function calculateMedian(list) {
-  const middleIndex = Math.floor(list.length / 2);
-  const median = list.splice(middleIndex, 1)[0];
-  return median;
+  if (!Array.isArray(list)) {
+    return null;
+  }
+
+  const numbers = list.filter((val) => typeof val === "number" && !isNaN(val));
+  if (numbers.length === 0) {
+    return null;
+  }
+
+  numbers.sort((a, b) => a - b);
+
+  const length = numbers.length;
+  const middle = Math.floor(length / 2);
+
+  if (length % 2 === 1) {
+    return numbers[middle];
+  } else {
+    return (numbers[middle - 1] + numbers[middle]) / 2;
+  }
 }
 
 module.exports = calculateMedian;

Sprint-1/implement/dedupe.js

@@ -1 +1,9 @@
-function dedupe() {}
+function dedupe(list) {
+  if (!Array.isArray(list)) {
+    return [];
+  }
+
+  return [...new Set(list)];
+}
+
+module.exports = dedupe;

Sprint-1/implement/dedupe.test.js

@@ -16,12 +16,26 @@ 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 a copy of the original array", () => {
+  const input = [1, 2, 3, 4];
+  const result = dedupe(input);
+
+  expect(result).toEqual([1, 2, 3, 4]);
+  expect(result).not.toBe(input);
+});
 
 // 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("given an array with strings or numbers, it removes duplicates and preserves 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]);
+  expect(dedupe([1, 2, 1])).toEqual([1, 2]);
+});

Sprint-1/implement/max.js

@@ -1,4 +1,12 @@
 function findMax(elements) {
+  if (!Array.isArray(elements)) {
+    return -Infinity;
+  }
+
+  const numbers = elements.filter(
+    (element) => typeof element === "number" && !Number.isNaN(element)
+  );
+  return numbers.length === 0 ? -Infinity : Math.max(...numbers);
 }
 
 module.exports = findMax;

Sprint-1/implement/max.test.js

@@ -16,28 +16,49 @@ 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 -Infinity", () => {
+  expect(findMax([])).toBe(-Infinity);
+});
 
 // 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([42])).toBe(42);
+});
 
 // 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 overall", () => {
+  expect(findMax([-10, 4, -2, 15, 7])).toBe(15);
+});
 
 // 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 closest one to zero", () => {
+  expect(findMax([-8, -3, -20, -11])).toBe(-3);
+});
 
 // 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", () => {
+  expect(findMax([1.2, 3.14, 3.139, -0.5])).toBe(3.14);
+});
 
 // 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("given non-number values, ignores them and returns max number", () => {
+  expect(findMax(["hey", 10, "hi", 60, 10])).toBe(60);
+  expect(findMax([null, undefined, 4, "9", true, 2])).toBe(4);
+});
 
 // 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 -Infinity", () => {
+  expect(findMax(["a", null, undefined, false, {}])).toBe(-Infinity);
+});

Sprint-1/implement/sum.js

@@ -1,4 +1,11 @@
 function sum(elements) {
+  if (!Array.isArray(elements)) {
+    return 0;
+  }
+
+  return elements
+    .filter((element) => typeof element === "number" && !Number.isNaN(element))
+    .reduce((total, number) => total + number, 0);
 }
 
 module.exports = sum;

Sprint-1/implement/sum.test.js

@@ -13,24 +13,42 @@ 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([42])).toBe(42);
+});
 
 // Given an array containing negative numbers
 // When passed to the sum function
 // Then it should still return the correct total sum
+test("given an array with negative numbers, returns correct total", () => {
+  expect(sum([10, -5, -2, 3])).toBe(6);
+});
 
 // 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 correct total", () => {
+  expect(sum([1.2, 0.6, 0.005])).toBeCloseTo(1.805, 10);
+});
 
 // 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("given non-number values, ignores them and sums numbers", () => {
+  expect(sum(["hey", 10, "hi", 60, 10])).toBe(80);
+  expect(sum([null, 4, "5", true, undefined, 6])).toBe(10);
+});
 
 // 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(["a", null, undefined, false, {}])).toBe(0);
+});

Sprint-1/refactor/includes.js

@@ -1,8 +1,7 @@
 // Refactor the implementation of includes to use a for...of loop
 
 function includes(list, target) {
-  for (let index = 0; index < list.length; index++) {
-    const element = list[index];
+  for (const element of list) {
     if (element === target) {
       return true;
     }