follow along with tests

parts/4/blogApp/tests/average.test.js

@@ -0,0 +1,18 @@
+const { test, describe } = require('node:test')
+const assert = require('node:assert')
+
+const average = require('../src/utils').average
+
+describe('average', () => {
+  test('of one value is the value itself', () => {
+    assert.strictEqual(average([1]), 1)
+  })
+
+  test('of many is calculated right', () => {
+    assert.strictEqual(average([1, 2, 3, 4, 5, 6]), 3.5)
+  })
+
+  test('of empty array is zero', () => {
+    assert.strictEqual(average([]), 0)
+  })
+})

parts/4/blogApp/tests/reverse.test.js

@@ -0,0 +1,22 @@
+const { test } = require('node:test')
+const assert = require('node:assert')
+
+const reverse = require('../src/utils.js').reverse
+
+test('reverse of a', () => {
+  const result = reverse('a')
+
+  assert.strictEqual(result, 'a')
+})
+
+test('reverse of react', () => {
+  const result = reverse('react')
+
+  assert.strictEqual(result, 'tcaer')
+})
+
+test('reverse of saippuakauppias', () => {
+  const result = reverse('saippuakauppias')
+
+  assert.strictEqual(result, 'saippuakauppias')
+})