NaN and Infinite changes applied to function and test cases added

Author: mervereis

Sprint-1/fix/median.js

@@ -14,25 +14,26 @@
 // module.exports = calculateMedian;
 
 function calculateMedian(list) {
-  if (!Array.isArray(list)) {
+  if (!Array.isArray(list) || list.length === 0) {
     return null;
   }
 
-  const numbers = list.filter((item) => typeof item === "number");
+  const numbers = list.filter((item) => Number.isFinite(item));
 
   if (numbers.length === 0) {
     return null;
   }
 
-  numbers.sort((a, b) => a - b);
+  // Copy before sort (extra safety, though filter already creates new array)
+  const sorted = [...numbers].sort((a, b) => a - b);
 
-  const middle = Math.floor(numbers.length / 2);
+  const middle = Math.floor(sorted.length / 2);
 
-  if (numbers.length % 2 === 0) {
-    return (numbers[middle - 1] + numbers[middle]) / 2;
+  if (sorted.length % 2 === 0) {
+    return (sorted[middle - 1] + sorted[middle]) / 2;
   }
 
-  return numbers[middle];
+  return sorted[middle];
 }
 
 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 +56,33 @@ 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))
+  );
+});
+
+describe("calculateMedian - ignores non-finite numbers", () => {
+  [
+    { input: [1, 2, NaN, 3], expected: 2 },
+    { input: [1, 2, Infinity, 3], expected: 2 },
+    { input: [1, 2, -Infinity, 3], expected: 2 },
+    { input: [1, 2, NaN, Infinity, -Infinity, 3], expected: 2 },
+    { input: [NaN, Infinity, -Infinity, 5, 10], expected: 7.5 },
+  ].forEach(({ input, expected }) =>
+    it(`ignores NaN/Infinity values in [${input}]`, () => {
+      expect(calculateMedian(input)).toEqual(expected);
+    })
   );
+
+  it("returns null when all values are non-finite", () => {
+    expect(calculateMedian([NaN, Infinity, -Infinity])).toBe(null);
+  });
+
+  it("handles mix of finite and non-finite with even count", () => {
+    expect(calculateMedian([1, 2, 3, 4, Infinity, NaN])).toBe(2.5);
+  });
+
+  it("handles mix of finite and non-finite with odd count", () => {
+    expect(calculateMedian([1, 2, 3, Infinity, NaN])).toBe(2);
+  });
 });