Cape Town | 26-ITP-Jan | Pretty Taruvinga | 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((x) => typeof x === "number" && !isNaN(x))
+    .sort((a, b) => a - b);
+
+  if (numbers.length === 0) {
+    return null;
+  }
+
+  const mid = Math.floor(numbers.length / 2);
+
+  if (numbers.length % 2 === 0) {
+    return (numbers[mid - 1] + numbers[mid]) / 2;
+  } else {
+    return numbers[mid];
+  }
 }
 
 module.exports = calculateMedian;

Sprint-1/implement/dedupe.js

@@ -1 +1,7 @@
-function dedupe() {}
+function dedupe(list) {
+  if (!Array.isArray(list)) {
+    return null;
+  }
+  return list.filter((value, index, self) => self.indexOf(value) === index);
+}
+module.exports = dedupe;

Sprint-1/implement/dedupe.test.js

@@ -16,13 +16,42 @@ 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, when passed to the dedupe function, then it should return an empty array", () => {
+  expect(dedupe([])).toEqual([]);
+});
+
+// Given a non-array value
+// When passed to the dedupe function
+// Then it should return null
+test("Given a non-array value, when passed to the dedupe function, then it should return null", () => {
+  expect(dedupe("not an array")).toBeNull();
+  expect(dedupe(123)).toBeNull();
+  expect(dedupe({})).toBeNull();
+});
 
 // 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, when passed to the dedupe function, then it should return a copy of the original array", () => {
+  const input = ["a", "b", "c"];
+  const result = dedupe(input);
+
+  expect(result).toEqual(input);
+  expect(result).not.toBe(input);
+  expect(result.length).toBe(input.length);
+});
 
 // 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 
-// first occurrence of each element from the original array.
+// Then it should remove the duplicate values, preserving the first occurrence of each element
+test("Given an array with strings or numbers, when passed to the dedupe function, then it should remove the duplicate values, preserving the first occurrence of each element", () => {
+  expect(dedupe(["a", "a", "b", "c", "c"])).toEqual(["a", "b", "c"]);
+  expect(dedupe([1, 2, 2, 3, 4, 4])).toEqual([1, 2, 3, 4]);
+});
+
+test("preserves the original order of first occurrences", () => {
+  const input = ["b", "a", "b", "c"];
+  const result = dedupe(input);
+
+  expect(result).toEqual(["b", "a", "c"]);
+});

Sprint-1/implement/max.js

@@ -1,4 +1,12 @@
-function findMax(elements) {
+function max(numbers) {
+  let max = -Infinity;
+
+  for (let num of numbers) {
+    if (typeof num === "number" && num > max) {
+      max = num;
+    }
+  }
+  return max;
 }
 
-module.exports = findMax;
+module.exports = max;

Sprint-1/implement/max.test.js

@@ -16,28 +16,55 @@ 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, when passed to the max function, then it should return -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, when passed to the max function, then it should return 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 an array with both positive and negative numbers, when passed to the max function, then it should return the largest number overall", () => {
+  expect(findMax([-10, -5, 0, 5, 10])).toBe(10);
+});
 
 // 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, when passed to the max function, then it should return the closest one to zero", () => {
+  expect(findMax([-10, -5, -1])).toBe(-1);
+});
 
 // 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, when passed to the max function, then it should return the largest decimal number", () => {
+  expect(findMax([1.5, 2.3, 0.8, 3.1])).toBe(3.1);
+});
 
 // 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, when passed to the max function, then it should return the max and ignore non-numeric values", () => {
+  expect(findMax(["hey", 10, "300", "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 an array with only non-number values, when passed to the max function, then it should return -Infinity", () => {
+  expect(findMax(["hey", "hi", "hello"])).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, when passed to the max function, then it should return that number", () => {
+  expect(findMax([42])).toBe(42);
+});

Sprint-1/implement/sum.js

@@ -1,4 +1,14 @@
 function sum(elements) {
+  if (!Array.isArray(elements)) {
+    return null;
+  }
+  let total = 0;
+  for (let i = 0; i < elements.length; i++) {
+    if (typeof elements[i] === "number" && !isNaN(elements[i])) {
+      total += elements[i];
+    }
+  }
+  return total;
 }
 
 module.exports = sum;

Sprint-1/implement/sum.test.js

@@ -13,24 +13,50 @@ 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, when passed to the sum function, then it should return 0", () => {
+  expect(sum([])).toBe(0);
+});
+
+// Given a non-array value
+// When passed to the sum function
+// Then it should return null
+test("Given a non-array value, when passed to the sum function, then it should return null", () => {
+  expect(sum("not an array")).toBeNull();
+  expect(sum(123)).toBeNull();
+  expect(sum({})).toBeNull();
+});
 
 // 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, when passed to the sum function, then it should return 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 containing negative numbers, when passed to the sum function, then it should still return the correct total sum", () => {
+  expect(sum([-10, -20, -30])).toBe(-60);
+});
 
 // 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, when passed to the sum function, then it should return the correct total sum", () => {
+  expect(sum([1.5, 2.3, 0.8, 3.1])).toBeCloseTo(7.7, 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 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", () => {
+  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 an array with only non-number values, when passed to the sum function, then it should return 0", () => {
+  expect(sum(["hey", "hi", "hello"])).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;
     }