message: observe tests when pushed
diff: /* eslint-disable */
  import { observe } from "mobx";
  import Suite from "../../models/Suite";
  +import Test from "../../models/Test";
  describe("Suite model", () => {
  it("new suite should be named 'Utitled Suite'", () => {
  @@ -17,4 +18,11 @@ describe("Suite model", () => {
  it("Tests should have randomly generated identifiers", () => {
  expect((new Suite()).id).not.toBe((new Suite()).id);
  });
  + it("should observe when a new Test is added", () => {
  + const suite = new Suite();
  + const disposer = observe(suite, "tests", (change) => {
  + expect(change.newValue.length).toBe(1);
  + });
  + suite.tests.push(new Test());
  + });
  });
  