Setup tests (#87)

* test: move timeout tests to their own job to speed things up slightly

* test: add comment about timeout tests

* test: fix needs in cd job

* test: add jest configuration and first test

* test: setup codecov to track coverage

src/util.test.ts

@@ -0,0 +1,17 @@
+import 'jest';
+import { getHeapStatistics } from 'v8';
+
+import { wait } from './util';
+
+// mocks the setTimeout function, see https://jestjs.io/docs/timer-mocks
+jest.useFakeTimers();
+jest.spyOn(global, 'setTimeout');
+
+describe('util', () => {
+  test('wait', async () => {
+    const waitTime = 1000;
+    wait(waitTime);
+    expect(setTimeout).toHaveBeenCalledTimes(1);
+    expect(setTimeout).toHaveBeenLastCalledWith(expect.any(Function), waitTime);
+  });
+});