@Test
 public void testThatCountsExactlyOneSubmittedRequest() throws Exception {
   executorService.submit(new MockTextQuery(), Optional.empty());
   executorService.submit(new MockTextQuery(), Optional.empty());
   executorService.submit(new MockTextQuery(), Optional.empty());
   sleep(MockTextProvider.FETCH_DELAY / 2);
   assertEquals(1, executorService.countSubmitted());
 }
 @Test(timeout = 60000)
 public void testThatInProgressTaskCountWell() throws Exception {
   MockTextQuery query1 = new MockTextQuery();
   MockTextQuery query2 = new MockTextQuery();
   executorService.submit(query1, Optional.empty());
   executorService.submit(query2, Optional.empty());
   sleep(MockTextProvider.FETCH_DELAY / 2);
   assertEquals(2, this.executorService.countInProgress());
 }
 @Test(timeout = 60000)
 public void testThatCallbackContainsCorrectQuery() throws Exception {
   MockTextQuery task = new MockTextQuery();
   Set<MockTextQuery> result = new HashSet<>();
   ExecutionCallback<MockTextQuery, MockTextProduct> callback = (t, p) -> result.add(t);
   executorService.submit(task, Optional.of(callback));
   executorService.shutdown();
   assertTrue(task == result.iterator().next());
 }
 @Test(timeout = 60000)
 public void testThatShutdownMethodWaitsAllCurrentTask() throws Exception {
   MockTextQuery request1 = new MockTextQuery();
   MockTextQuery request2 = new MockTextQuery();
   executorService.submit(request1, Optional.empty());
   executorService.submit(request2, Optional.empty());
   sleep(MockTextProvider.FETCH_DELAY / 2);
   executorService.shutdown();
   assertEquals(0, this.executorService.countInProgress());
 }
 @Test(timeout = 60000)
 public void testThatProductWillBeReturnedViaCallback() throws Exception {
   MockTextQuery task = new MockTextQuery("ping");
   Set<String> result = new HashSet<>();
   ExecutionCallback<MockTextQuery, MockTextProduct> callback =
       (t, p) -> result.add(p.get().getResponse());
   executorService.submit(task, Optional.of(callback));
   executorService.shutdown();
   assertEquals("ping_pong", result.iterator().next());
 }
 @Test(timeout = 60000, expected = IllegalStateException.class)
 public void testThatCanNotSubmitWhenInShutdownState() throws Exception {
   new Thread(
           () -> {
             try {
               sleep(1000);
               executorService.shutdown();
             } catch (InterruptedException ignored) {
             }
           })
       .start();
   for (int i = 0; i < 10; i++) {
     executorService.submit(new MockTextQuery(), Optional.empty());
     sleep(MockTextProvider.FETCH_DELAY / 2);
   }
   assertTrue("service is not allowed to accept submissions after shutdown", false);
 }