Birmingham | 25-ITP-Sept | Khor Biel | Sprint 1 | module-data-group/sprint-1

Sprint-1/fix/median.js

@@ -5,10 +5,29 @@
 // Hint: Please consider scenarios when 'list' doesn't have numbers (the function is expected to return null)
 // 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) => Number.isFinite(item));
+
+  if (numbers.length === 0) {
+    return null;
+  }
+
+  numbers.sort((a, b) => a - b);
+
+  const middleIndex = Math.floor(numbers.length / 2);
+
+  if (numbers.length % 2 === 1) {
+    return numbers[middleIndex];
+  } else {
+    return (numbers[middleIndex - 1] + numbers[middleIndex]) / 2;
+  }
 }
 
+
 module.exports = calculateMedian;

Sprint-1/implement/dedupe.js

@@ -1 +1,7 @@
-function dedupe() {}
+
+function dedupe(arr) {
+  return [...new Set(arr)];
+}
+
+module.exports = dedupe;
+

Sprint-1/implement/dedupe.test.js

@@ -16,12 +16,31 @@ 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 (not the same array)", () => {
+  const arr1 = [1, 2, 3];
+  const result1 = dedupe(arr1);
+
+  expect(result1).toEqual(arr1); // values match
+  expect(result1).not.toBe(arr1); // different reference
+
+  const arr2 = ["a", "b", "c"];
+  const result2 = dedupe(arr2);
+
+  expect(result2).toEqual(arr2);
+  expect(result2).not.toBe(arr2);
+});
 
 // 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 duplicates, it removes the duplicates preserving the first occurrence", () => {
+  expect(dedupe(["a", "a", "b", "c", "b"])).toEqual(["a", "b", "c"]);
+  expect(dedupe([5, 1, 1, 2, 3, 2, 5, 8])).toEqual([5, 1, 2, 3, 8]);
+});

Sprint-1/implement/max.js

@@ -1,4 +1,13 @@
 function findMax(elements) {
+  if (!Array.isArray(elements)) return -Infinity;
+
+  const numbers = elements.filter(
+    (item) => typeof item === "number" && Number.isFinite(item)
+  );
+
+  if (numbers.length === 0) return -Infinity;
+
+  return Math.max(...numbers);
 }
 
 module.exports = findMax;

Sprint-1/implement/max.test.js

@@ -12,32 +12,68 @@ We have set things up already so that this file can see your function from the o
 
 const findMax = require("./max.js");
 
-// Given an empty array
-// 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");
-
-// Given an array with one number
-// When passed to the max function
-// Then it should return that number
-
-// Given an array with both positive and negative numbers
-// When passed to the max function
-// Then it should return the largest number overall
-
-// Given an array with just negative numbers
-// When passed to the max function
-// Then it should return the closest one to zero
-
-// Given an array with decimal numbers
-// When passed to the max function
-// Then it should return the largest decimal number
-
-// Given an array with non-number values
-// When passed to the max function
-// Then it should return the max and ignore non-numeric values
-
-// 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
+describe("findMax", () => {
+  // Given an empty array
+  // When passed to the max function
+  // Then it should return -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([5])).toBe(5);
+    expect(findMax([-10])).toBe(-10);
+    expect(findMax([0])).toBe(0);
+  });
+
+  // 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 largest", () => {
+    expect(findMax([30, 50, 10, 40])).toBe(50);
+    expect(findMax([-5, -1, -10])).toBe(-1);
+    expect(findMax([10, -5, 20, -15])).toBe(20);
+  });
+
+  // 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, returns the closest to zero", () => {
+    expect(findMax([-5, -1, -10])).toBe(-1);
+    expect(findMax([-100, -50, -25])).toBe(-25);
+  });
+
+  // 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, returns the largest decimal", () => {
+    expect(findMax([1.5, 2.7, 1.2])).toBe(2.7);
+    expect(findMax([0.1, 0.01, 0.001])).toBe(0.1);
+    expect(findMax([-1.5, -2.7, -1.2])).toBe(-1.2);
+  });
+
+  // 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, ignores them and returns the max number", () => {
+    expect(findMax(["hey", 10, "hi", 60, 10])).toBe(60);
+    expect(findMax([30, "hello", 50, null, undefined, 40])).toBe(50);
+    expect(findMax([true, false, 25, 15])).toBe(25);
+  });
+
+  // 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, returns -Infinity", () => {
+    expect(findMax(["hello", "world"])).toBe(-Infinity);
+    expect(findMax([null, undefined])).toBe(-Infinity);
+    expect(findMax([true, false])).toBe(-Infinity);
+    expect(findMax([{}, []])).toBe(-Infinity);
+  });
+});
+
+
+

Sprint-1/implement/sum.js

@@ -1,4 +1,11 @@
 function sum(elements) {
+  // Filter out only numeric values
+  const numbers = elements.filter(
+    (item) => typeof item === "number" && Number.isFinite(item)
+  );
+
+  // Sum all numbers using reduce
+  return numbers.reduce((total, num) => total + num, 0);
 }
 
 module.exports = sum;

Sprint-1/implement/sum.test.js

@@ -8,29 +8,40 @@ E.g. sum(['hey', 10, 'hi', 60, 10]), target output: 80 (ignore any non-numerical
 
 const sum = require("./sum.js");
 
-// Acceptance Criteria:
-
-// Given an empty array
-// When passed to the sum function
-// Then it should return 0
-test.todo("given an empty array, returns 0")
-
-// Given an array with just one number
-// When passed to the sum function
-// Then it should return that number
-
-// Given an array containing negative numbers
-// When passed to the sum function
-// Then it should still return the correct total sum
-
-// Given an array with decimal/float numbers
-// When passed to the sum function
-// Then it should return the correct total sum
-
-// 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
-
-// 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
+describe("sum", () => {
+  test("given an empty array, returns 0", () => {
+    expect(sum([])).toBe(0);
+  });
+
+  test("given an array with one number, returns that number", () => {
+    expect(sum([5])).toBe(5);
+    expect(sum([-10])).toBe(-10);
+    expect(sum([0])).toBe(0);
+  });
+
+  test("given an array containing negative numbers, returns correct sum", () => {
+    expect(sum([10, -5, 3])).toBe(8);
+    expect(sum([-1, -2, -3])).toBe(-6);
+    expect(sum([-10, 20, -5])).toBe(5);
+  });
+
+  test("given an array with decimal numbers, returns correct sum", () => {
+    expect(sum([1.5, 2.5, 1.0])).toBeCloseTo(5);
+    expect(sum([0.1, 0.2, 0.3])).toBeCloseTo(0.6);
+    expect(sum([-1.5, 2.5, -1.0])).toBeCloseTo(0);
+  });
+
+  test("given an array with non-number values, ignores them and returns sum of numbers", () => {
+    expect(sum(["hey", 10, "hi", 60, 10])).toBe(80);
+    expect(sum([30, "hello", 50, null, undefined, 40])).toBe(120);
+    expect(sum([true, false, 25, 15])).toBe(40);
+    expect(sum([10, "20", 30])).toBe(40); // string '20' ignored
+  });
+
+  test("given an array with only non-number values, returns 0", () => {
+    expect(sum(["hello", "world"])).toBe(0);
+    expect(sum([null, undefined])).toBe(0);
+    expect(sum([true, false])).toBe(0);
+    expect(sum([{}, []])).toBe(0);
+  });
+});

Sprint-1/refactor/includes.js

@@ -1,8 +1,11 @@
 // 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];
+  if (!Array.isArray(list)) {
+    return false;
+  }
+
+  for (const element of list) {
     if (element === target) {
       return true;
     }