Sheffield | 26-Jan-ITP | Daniel Aderibigbe | Sprint 1 | Coursework/sprint 1

Sprint-1/fix/median.js

@@ -6,9 +6,22 @@
 // or 'list' has mixed values (the function is expected to sort only numbers).
 
 function calculateMedian(list) {
+  if (!Array.isArray(list)) {
+    return null;
+  }
+  list = list.filter((item) => typeof item === "number");
+  if (list.length === 0) {
+    return null;
+  }
+  list = [...list].sort((a, b) => a - b);
+
   const middleIndex = Math.floor(list.length / 2);
-  const median = list.splice(middleIndex, 1)[0];
-  return median;
+  const median = list[middleIndex];
+  if (list.length % 2) {
+    return median;
+  } else {
+    return (median + list[middleIndex - 1]) / 2;
+  }
 }
 
 module.exports = calculateMedian;

Sprint-1/implement/dedupe.js

@@ -1 +1,12 @@
-function dedupe() {}
+function dedupe(array) {
+  const result = [];
+
+  for (const item of array) {
+    if (!result.includes(item)) {
+      result.push(item);
+    }
+  }
+  return result;
+}
+
+module.exports = dedupe;

Sprint-1/implement/dedupe.test.js

@@ -16,13 +16,31 @@ 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", () => {
+  const input = [];
+  const expectedOutput = [];
+  expect(dedupe(input)).toEqual(expectedOutput);
+});
 
 // 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 expectedOutput = [1, 2, 3];
+  const result = dedupe(input);
+
+  expect(result).toEqual(expectedOutput);
+  expect(result).not.toBe(input);
+});
 
 // Given an array of 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 the duplicate values, preserving the first occurence of each element", () => {
+  const input = [5, 1, 1, 2, 3, 2, 5, 8, "egg", "egg", "bacon"];
+  const expectedOutput = [5, 1, 2, 3, 8, "egg", "bacon"];
+  expect(dedupe(input)).toEqual(expectedOutput);
+});
 // Then it should return a new array with duplicates removed while preserving the 
 // first occurrence of each element from the original array.

Sprint-1/implement/max.js

@@ -1,4 +1,16 @@
 function findMax(elements) {
+  let max = -Infinity;
+
+  for (let i = 0; i < elements.length; i++) {
+    if (
+      typeof elements[i] === "number" &&
+      !Number.isNaN(elements[i]) &&
+      elements[i] > max
+    ) {
+      max = elements[i];
+    }
+  }
+  return max;
 }
 
 module.exports = findMax;

Sprint-1/implement/max.test.js

@@ -16,28 +16,62 @@ 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", () => {
+  const input = [];
+  const expectedOutput = -Infinity;
+  expect(findMax(input)).toBe(expectedOutput);
+});
 
 // 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, it returns that number", () => {
+  const input = [42];
+  const expectedOutput = 42;
+  expect(findMax(input)).toBe(expectedOutput);
+});
 
 // 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, it returns the largest number overall", () => {
+  const input = [-10, -20, 5, 0, -1];
+  const expectedOutput = 5;
+  expect(findMax(input)).toBe(expectedOutput);
+});
 
 // 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, it returns the closest one to zero", () => {
+  const input = [-10, -20, -5, -1];
+  const expectedOutput = -1;
+  expect(findMax(input)).toBe(expectedOutput);
+});
 
 // 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, it returns the largest decimal number", () => {
+  const input = [1.5, 2.3, 0.7, 2.9];
+  const expectedOutput = 2.9;
+  expect(findMax(input)).toBe(expectedOutput);
+});
 
 // 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, it returns the max and ignore non-numeric values", () => {
+  const input = [10, "300", "hello", 20, null, 5];
+  const expectedOutput = 20;
+  expect(findMax(input)).toBe(expectedOutput);
+});
 
 // 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, it returns the least surprising value", () => {
+  const input = ["hello", "world"];
+  const expectedOutput = -Infinity;
+  expect(findMax(input)).toBe(expectedOutput);
+});

Sprint-1/implement/sum.js

@@ -1,4 +1,12 @@
 function sum(elements) {
+  let total = 0;
+
+  for (let i = 0; i < elements.length; i++) {
+    if (Number.isFinite(elements[i])) {
+      total += elements[i];
+    }
+  }
+  return total;
 }
 
 module.exports = sum;

Sprint-1/implement/sum.test.js

@@ -13,24 +13,53 @@ 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", () => {
+  const input = [];
+  const expectedOutput = 0;
+  expect(sum(input)).toBe(expectedOutput);
+});
 
 // Given an array with just one number
 // When passed to the sum function
 // Then it should return that number
+test("given an array with just one number, returns that number", () => {
+  const input = [5];
+  const expectedOutput = 5;
+  expect(sum(input)).toBe(expectedOutput);
+});
 
 // 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 containing negative numbers, it returns the correct total sum", () => {
+  const input = [10, -5, 20, -3];
+  const expectedOutput = 22;
+  expect(sum(input)).toBe(expectedOutput);
+});
 
 // 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 numbers, it returns the correct total sum", () => {
+  const input = [1.5, 2.3, 0.7];
+  const expectedOutput = 4.5;
+  expect(sum(input)).toBeCloseTo(expectedOutput);
+});
 
 // 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, it ignores them and returns the sum of the numerical elements", () => {
+  const input = [10, "hello", 20, null, 5];
+  const expectedOutput = 35;
+  expect(sum(input)).toBe(expectedOutput);
+});
 
 // 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, it returns the least surprising value", () => {
+  const input = ["hello", "world"];
+  const expectedOutput = 0;
+  expect(sum(input)).toBe(expectedOutput);
+});

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;
     }

Sprint-1/stretch/aoc-2018-day1/solution.js

@@ -0,0 +1,3 @@
+function sum(list) {
+  return list.reduce((a, b) => a + b, 0);
+}