West Midlands | ITP-Sep-25 | Baba Yusuf | Sprint 1 | Module-data-groups/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) {
-  const middleIndex = Math.floor(list.length / 2);
-  const median = list.splice(middleIndex, 1)[0];
-  return median;
+  if (!Array.isArray(list)) {
+    return null;
+  }
+  const numericValues = list.filter(
+    (val) => typeof val === "number" && !isNaN(val)
+  );
+  if (numericValues.length === 0) {
+    return null;
+  }
+  const sorted = [...numericValues].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/fix/median.test.js

@@ -13,7 +13,8 @@ describe("calculateMedian", () => {
     { input: [1, 2, 3, 4], expected: 2.5 },
     { input: [1, 2, 3, 4, 5, 6], expected: 3.5 },
   ].forEach(({ input, expected }) =>
-    it(`returns the median for [${input}]`, () => expect(calculateMedian(input)).toEqual(expected))
+    it(`returns the median for [${input}]`, () =>
+      expect(calculateMedian(input)).toEqual(expected))
   );
 
   [
@@ -24,7 +25,8 @@ describe("calculateMedian", () => {
     { input: [110, 20, 0], expected: 20 },
     { input: [6, -2, 2, 12, 14], expected: 6 },
   ].forEach(({ input, expected }) =>
-    it(`returns the correct median for unsorted array [${input}]`, () => expect(calculateMedian(input)).toEqual(expected))
+    it(`returns the correct median for unsorted array [${input}]`, () =>
+      expect(calculateMedian(input)).toEqual(expected))
   );
 
   it("doesn't modify the input array [3, 1, 2]", () => {
@@ -33,8 +35,17 @@ describe("calculateMedian", () => {
     expect(list).toEqual([3, 1, 2]);
   });
 
-  [ 'not an array', 123, null, undefined, {}, [], ["apple", null, undefined] ].forEach(val =>
-    it(`returns null for non-numeric array (${val})`, () => expect(calculateMedian(val)).toBe(null))
+  [
+    "not an array",
+    123,
+    null,
+    undefined,
+    {},
+    [],
+    ["apple", null, undefined],
+  ].forEach((val) =>
+    it(`returns null for non-numeric array (${val})`, () =>
+      expect(calculateMedian(val)).toBe(null))
   );
 
   [
@@ -45,6 +56,7 @@ describe("calculateMedian", () => {
     { input: [3, "apple", 1, null, 2, undefined, 4], expected: 2.5 },
     { input: ["banana", 5, 3, "apple", 1, 4, 2], expected: 3 },
   ].forEach(({ input, expected }) =>
-    it(`filters out non-numeric values and calculates the median for [${input}]`, () => expect(calculateMedian(input)).toEqual(expected))
+    it(`filters out non-numeric values and calculates the median for [${input}]`, () =>
+      expect(calculateMedian(input)).toEqual(expected))
   );
 });

Sprint-1/implement/dedupe.js

@@ -1 +1,15 @@
-function dedupe() {}
+function dedupe(arr) {
+  if (!Array.isArray(arr)) {
+    return [];
+  }
+  const seen = new Set();
+  return arr.filter((item) => {
+    if (seen.has(item)) {
+      return false;
+    }
+    seen.add(item);
+    return true;
+  });
+}
+
+module.exports = dedupe;

Sprint-1/implement/dedupe.test.js

@@ -12,16 +12,27 @@ E.g. dedupe([1, 2, 1]) target output: [1, 2]
 */
 
 // Acceptance Criteria:
+describe("dedupe", () => {
+  // Given an empty array
+  // When passed to the dedupe function
+  // Then it should return an empty array
+  it("given an empty array, it returns an empty array", () => {
+    expect(dedupe([])).toEqual([]);
+  });
 
-// 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");
-
-// Given an array with no duplicates
-// When passed to the dedupe function
-// Then it should return a copy of the original array
-
-// 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
+  // Given an array with no duplicates
+  // When passed to the dedupe function
+  // Then it should return a copy of the original array
+  it("given an array with no duplicates, returns a copy of the original array", () => {
+    expect(dedupe([1, 2, 3])).toEqual([1, 2, 3]);
+    expect(dedupe(["a", "b", "c"])).toEqual(["a", "b", "c"]);
+  });
+  // 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
+  it("given an array with strings or numbers, removes duplicates preserving the 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 +1,17 @@
 function findMax(elements) {
+  if (!Array.isArray(elements)) {
+    return -Infinity;
+  }
+
+  const numericValues = elements.filter(
+    (val) => typeof val === "number" && !isNaN(val)
+  );
+
+  if (numericValues.length === 0) {
+    return -Infinity;
+  }
+
+  return Math.max(...numericValues);
 }
 
 module.exports = findMax;

Sprint-1/implement/max.test.js

@@ -16,28 +16,42 @@ 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");
-
+it("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
-
+it("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
-
+it("given an array with both positive and negative numbers, returns the largest number", () => {
+  expect(findMax([-10, 0, 5, 20, -3])).toBe(20);
+});
 // Given an array with just negative numbers
 // When passed to the max function
 // Then it should return the closest one to zero
-
+it("given an array with only negative numbers, returns the closest to zero", () => {
+  expect(findMax([-10, -3, -20])).toBe(-3);
+});
 // Given an array with decimal numbers
 // When passed to the max function
 // Then it should return the largest decimal number
-
+it("given an array with decimal numbers, returns the largest decimal", () => {
+  expect(findMax([1.1, 2.5, 2.49])).toBe(2.5);
+});
 // Given an array with non-number values
 // When passed to the max function
 // Then it should return the max and ignore non-numeric values
-
+it("given an array with non-number values, returns the max and ignores non-numeric values", () => {
+  expect(findMax(["hey", 10, "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
+it("given an array with only non-number values, returns -Infinity", () => {
+  expect(findMax(["apple", "banana", null, undefined])).toBe(-Infinity);
+});

Sprint-1/implement/sum.js

@@ -1,4 +1,9 @@
 function sum(elements) {
+  if (!Array.isArray(elements)) return 0;
+
+  return elements
+    .filter((val) => typeof val === "number" && !isNaN(val))
+    .reduce((acc, val) => acc + val, 0);
 }
 
 module.exports = sum;

Sprint-1/implement/sum.test.js

@@ -13,24 +13,37 @@ 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")
+it("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
-
+it("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
-
+it("given an array with negative numbers, returns the correct sum", () => {
+  expect(sum([-10, 5, -3, 8])).toBe(0);
+});
 // Given an array with decimal/float numbers
 // When passed to the sum function
 // Then it should return the correct total sum
-
+it("given an array with decimal numbers, returns the correct sum", () => {
+  expect(sum([1.1, 2.5, 3.4])).toBeCloseTo(7.0); // use toBeCloseTo for floating point
+});
 // 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
-
+it("given an array with non-number values, sums only the numbers", () => {
+  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
+it("given an array with only non-number values, returns 0", () => {
+  expect(sum(["apple", "banana", null, undefined])).toBe(0);
+});