findMax function created & test cases created

Author: mervereis

Sprint-1/implement/max.js

@@ -1,4 +1,19 @@
 function findMax(elements) {
+  const numbers = elements.filter((el) => typeof el === "number");
+
+  if (numbers.length === 0) {
+    return -Infinity;
+  }
+
+  let max = numbers[0];
+
+  for (let i = 1; i < numbers.length; i++) {
+    if (numbers[i] > max) {
+      max = numbers[i];
+    }
+  }
+
+  return max;
 }
 
 module.exports = findMax;

Sprint-1/implement/max.test.js

@@ -1,43 +1,52 @@
-/* Find the maximum element of an array of numbers
-
-In this kata, you will need to implement a function that find the largest numerical element of an array.
-
-E.g. max([30, 50, 10, 40]), target output: 50
-E.g. max(['hey', 10, 'hi', 60, 10]), target output: 60 (sum ignores any non-numerical elements)
-
-You should implement this function in max.js, and add tests for it in this file.
-
-We have set things up already so that this file can see your function from the other file.
-*/
-
 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);
+  });
+
+  // Given an array with both positive and negative numbers
+  // When passed to the max function
+  // Then it should return the largest number overall
+  test("returns the largest number from positive and negative numbers", () => {
+    expect(findMax([-10, 20, -5, 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("returns the largest number among negative numbers", () => {
+    expect(findMax([-10, -3, -50, -1])).toBe(-1);
+  });
+
+  // Given an array with decimal numbers
+  // When passed to the max function
+  // Then it should return the largest decimal number
+  test("returns the largest decimal number", () => {
+    expect(findMax([1.2, 3.7, 2.5, 3.6])).toBe(3.7);
+  });
+
+  // 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("ignores non-number 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
+  test("returns -Infinity when array has only non-number values", () => {
+    expect(findMax(["a", "b", "c"])).toBe(-Infinity);
+  });
+});