Add "getType" test case

test/getType.test.js

@@ -12,3 +12,7 @@ test('Returns null for null', () => {
 test('Returns undefined for undefined', () => {
   expect(getType(undefined)).toBe('undefined');
 });
+class DummyClass{}
+test('Returns custom classes', () => {
+  expect(getType(new DummyClass())).toBe('dummyclass');
+});