Birmingham | 26-ITP-May | Ogbemi Mene | Sprint 1 | Module data group/sprint 1a

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) || list.length === 0) {
+    return null;
+  }
+  const numbersOnly = list.filter((element) => typeof element === "number");
+  if (numbersOnly.length === 0) {
+    return null;
+  }
+
+  const sortedList = [...numbersOnly].sort((a, b) => a - b);
+
+  if (sortedList.length % 2 === 0) {
+    const middleIndex = Math.floor(sortedList.length / 2);
+    return (sortedList[middleIndex - 1] + sortedList[middleIndex]) / 2;
+  }
+  const middleIndex = Math.floor(sortedList.length / 2);
+
+  return sortedList[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 +56,13 @@ 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))
   );
+
+  it("calculates the correct median for salaries array", () => {
+    const salaries = [10, 40, 50, 70, 90];
+    const median = calculateMedian(salaries);
+    expect(median).toEqual(50);
+  });
 });

Sprint-1/implement/dedupe.js

@@ -1 +1,9 @@
-function dedupe() {}
+function dedupe(list) {
+  if (!Array.isArray(list)) {
+    return [];
+  }
+
+  return [...new Set(list)];
+}
+
+module.exports = dedupe;

Sprint-1/implement/dedupe.test.js

@@ -16,13 +16,38 @@ 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.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 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.
+
+describe("dedupe function", () => {
+  test("should remove duplicate elements from an array", () => {
+    expect(dedupe([1, 2, 2, 3, 1, 4])).toEqual([1, 2, 3, 4]);
+    expect(dedupe(["apple", "banana", "apple", "orange"])).toEqual([
+      "apple",
+      "banana",
+      "orange",
+    ]);
+  });
+
+  test("should return the same array if there are no duplicates", () => {
+    expect(dedupe([1, 2, 3])).toEqual([1, 2, 3]);
+  });
+
+  test("should return an empty array if given an empty array", () => {
+    expect(dedupe([])).toEqual([]);
+  });
+
+  test("should return an empty array if given invalid input (non-arrays)", () => {
+    expect(dedupe(null)).toEqual([]);
+    expect(dedupe(undefined)).toEqual([]);
+    expect(dedupe("not an array")).toEqual([]);
+  });
+});

Sprint-1/implement/max.js

@@ -1,4 +1,18 @@
 function findMax(elements) {
+  if (!Array.isArray(elements) || elements.length === 0) {
+    return -Infinity;
+  }
+  let max = -Infinity;
+
+  for (const item of elements) {
+    if (typeof item === "number" && !Number.isNaN(item)) {
+      if (item > max) {
+        max = item;
+      }
+    }
+  }
+
+  return max;
 }
 
 module.exports = findMax;

Sprint-1/implement/max.test.js

@@ -41,3 +41,35 @@ test.todo("given an empty array, returns -Infinity");
 // 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 function", () => {
+  test("should return the maximum number in an array of positive numbers", () => {
+    expect(findMax([1, 5, 3, 9, 2])).toBe(9);
+  });
+
+  test("should return the maximum number in an array with negative numbers", () => {
+    expect(findMax([-10, -3, -50, -1])).toBe(-1);
+  });
+
+  test("should handle arrays with mixed types and ignore non-numbers", () => {
+    expect(findMax([1, "apple", 5, null, true, 3])).toBe(5);
+  });
+
+  test("should ignore NaN values", () => {
+    expect(findMax([1, NaN, 10, 2])).toBe(10);
+  });
+
+  test("should return -Infinity if given an empty array", () => {
+    expect(findMax([])).toBe(-Infinity);
+  });
+
+  test("should return -Infinity if given an array with no valid numbers", () => {
+    expect(findMax(["a", "b", null, NaN])).toBe(-Infinity);
+  });
+
+  test("should return -Infinity for non-array inputs", () => {
+    expect(findMax(null)).toBe(-Infinity);
+    expect(findMax(undefined)).toBe(-Infinity);
+    expect(findMax("hello")).toBe(-Infinity);
+  });
+});

Sprint-1/implement/sum.js

@@ -1,4 +1,14 @@
 function sum(elements) {
+  if (!Array.isArray(elements) || elements.length === 0) {
+    return 0;
+  }
+
+  const numbersOnly = elements.filter(
+    (item) => typeof item === "number" && !isNaN(item)
+  );
+
+
+  return numbersOnly.reduce((acc, curr) => acc + curr, 0);
 }
 
 module.exports = sum;

Sprint-1/implement/sum.test.js

@@ -13,7 +13,7 @@ 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.todo("given an empty array, returns 0");
 
 // Given an array with just one number
 // When passed to the sum function
@@ -34,3 +34,42 @@ test.todo("given an empty array, returns 0")
 // 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 function", () => {
+  // Given an empty array
+  test("given an empty array, returns 0", () => {
+    expect(sum([])).toBe(0);
+  });
+
+  // Given an array with just one number
+  test("given an array with just one number, returns that number", () => {
+    expect(sum([42])).toBe(42);
+  });
+
+  // Given an array containing negative numbers
+  test("given an array containing negative numbers, returns the correct total sum", () => {
+    expect(sum([10, -5, 20, -15])).toBe(10);
+  });
+
+  // Given an array with decimal/float numbers
+  test("given an array with decimal/float numbers, returns the correct total sum", () => {
+    expect(sum([1.5, 2.25, 3.25])).toBe(7);
+  });
+
+  // Given an array containing non-number values
+  test("given an array containing non-number values, ignores non-numerical values", () => {
+    expect(sum(["hey", 10, "hi", 60, 10])).toBe(80);
+    expect(sum([10, true, null, undefined, NaN, 20])).toBe(30);
+  });
+
+  // Given an array with only non-number values
+  test("given an array with only non-number values, returns 0", () => {
+    expect(sum(["apple", "banana", true, null])).toBe(0);
+  });
+
+  // Edge case: Non-array inputs
+  test("given non-array inputs, returns 0", () => {
+    expect(sum(null)).toBe(0);
+    expect(sum("not an array")).toBe(0);
+  });
+});