message: test the initial state
diff: @@ -14,6 +14,12 @@ describe("TickSource", () => {
  expect(source.frequency.value).to.equal(2);
  source.dispose();
  });
  +
  + it("initially returns stop", () => {
  + const source = new TickSource(2);
  + expect(source.state).to.equal("stopped");
  + source.dispose();
  + });
  });
  context("Ticks", () => {
  