Add tests for hasKey snippet

test/hasKey.test.js

@@ -0,0 +1,33 @@
+const {hasKey} = require('./_30s.js');
+
+const data = {
+  a: 1, b: { c: 4 }, 'd.e': 5
+};
+
+test('hasKey is a Function', () => {
+  expect(hasKey).toBeInstanceOf(Function);
+});
+
+test('hasKey returns true for simple property', () => {
+  expect(hasKey(data, 'a')).toBe(true);
+});
+
+test('hasKey returns true for object property', () => {
+  expect(hasKey(data, 'b')).toBe(true);
+});
+
+test('hasKey returns true for nested property', () => {
+  expect(hasKey(data, 'b.c')).toBe(true);
+});
+
+test('hasKey returns true for property with dots', () => {
+  expect(hasKey(data, 'd.e')).toBe(true);
+});
+
+test('hasKey returns false for non-existent property', () => {
+  expect(hasKey(data, 'f')).toBe(true);
+});
+
+test('hasKey returns false for virtual nested property', () => {
+  expect(hasKey(data, 'd')).toBe(false);
+});