Birmingham | 26-ITP-May | Toluwalase Tiamiyu | Sprint 1 | Exercises

Sprint-1/fix/median.js

@@ -6,9 +6,24 @@
 // 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((item) => typeof item === "number");
+
+  if (numbers.length === 0) {
+    return null;
+  }
+
+  const sorted = [...numbers].sort((a, b) => a - b);
+  const middleIndex = Math.floor(sorted.length / 2);
+
+  if (sorted.length % 2 === 0) {
+    return (sorted[middleIndex - 1] + sorted[middleIndex]) / 2;
+  } else {
+    return sorted[middleIndex];
+  }
 }
 
 module.exports = calculateMedian;

Sprint-1/implement/dedupe.js

@@ -1 +1,5 @@
-function dedupe() {}
+function dedupe(list) {
+  return list.filter((item, index) => index === list.indexOf(item));
+}
+
+module.exports = dedupe;

Sprint-1/implement/dedupe.test.js

@@ -16,13 +16,39 @@ E.g. dedupe([1, 2, 1]) returns [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];
+  const result = dedupe(input);
+
+  expect(result).toEqual(input);
+  expect(result).not.toBe(input);
+});
+
 // Given an array of strings or numbers
 // When passed to the dedupe function
-// Then it should return a new array with duplicates removed while preserving the 
+// Then it should return a new array with duplicates removed while preserving the
 // first occurrence of each element from the original array.
+
+test("given an array of numbers with duplicates, it returns a new array with duplicates removed preserving first occurrences", () => {
+  const input = [5, 1, 1, 2, 3, 2, 5, 8];
+  const result = dedupe(input);
+
+  expect(result).toEqual([5, 1, 2, 3, 8]);
+  expect(result).not.toBe(input);
+});
+
+test("given an array of strings with duplicates, it returns a new array with duplicates removed preserving first occurrences", () => {
+  const input = ["a", "a", "a", "b", "b", "c"];
+  const result = dedupe(input);
+
+  expect(result).toEqual(["a", "b", "c"]);
+  expect(result).not.toBe(input);
+});

Sprint-1/implement/max.js

@@ -1,4 +1,6 @@
 function findMax(elements) {
+  const numbers = elements.filter((item) => typeof item === "number");
+  return 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 the number", () => {
+  expect(findMax([12])).toBe(12);
+});
+
 // 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 an array with both positive and negative numbers, returns the highest number", () => {
+  expect(findMax([20, -21, 30])).toBe(30);
+});
 
 // Given an array with just negative numbers
 // When passed to the max function
 // Then it should return the closest one to zero
+test("given an array with just negative numbers, return the number closest to zero", () => {
+  expect(findMax([-12, -7, -20])).toBe(-7);
+});
 
 // Given an array with decimal numbers
 // When passed to the max function
 // Then it should return the largest decimal number
+test("given an array with decimal numbers, return the largest decimal number", () => {
+  expect(findMax([1.2, 1.3, 1.8])).toBe(1.8);
+});
 
 // 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 an array with non-number values, return the max and ignore the non-numerical values", () => {
+  expect(findMax(["boy", 2, "hi", 20, "120", 24])).toBe(24);
+});
 
 // 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 an array with only non-number values, return the least surprising value", () => {
+  expect(findMax(["a", "c", "e"])).toBe(-Infinity);
+});

Sprint-1/implement/sum.js

@@ -1,4 +1,8 @@
 function sum(elements) {
+  const numbers = elements.filter(
+    (item) => typeof item === "number" && !Number.isNaN(item)
+  );
+  return numbers.reduce((total, current) => total + current, 0);
 }
 
 module.exports = sum;

Sprint-1/implement/sum.test.js

@@ -13,24 +13,52 @@ 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, return the 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 an array with negative numbers, return the correct sum total", () => {
+  expect(sum([-1, -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 an array with decimal/float numbers, return the correct sum total", () => {
+  expect(sum([1.1, 1.2, 2.1])).toBeCloseTo(4.4);
+});
 // 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 an array containing non-number values, return correct sum total and ignore the non-numbers", () => {
+  expect(sum(["we", 2, "are", 18])).toBe(20);
+});
 // 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 an array with only non-number values, return the least surprising value", () => {
+  expect(sum(["the", "world"])).toBe(0);
+});
+// Given an array containing NaN and valid numbers
+// When passed to the sum function
+// Then it should ignore NaN and sum the valid numbers
+test("given an array containing NaN, ignores NaN and returns the sum of valid numbers", () => {
+  expect(sum([NaN, 1])).toBe(1);
+});
+
+// Given an array with positive and negative Infinity
+// When passed to the sum function
+// Then it should return NaN (undefined mathematical operation)
+test("given an array with Infinity and -Infinity, returns NaN", () => {
+  expect(sum([Infinity, -Infinity])).toBeNaN();
+});

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;
     }