@Test
  public void get() {
    assertEquals(111, context.get("pull1"));
    assertEquals(222, context.get("pull2"));
    assertEquals(333, context.get("parent"));
    assertEquals(444, context.get("child"));

    assertEquals(null, context.get("other"));
  }
  @Test
  public void create_no_pullContext() {
    context = new PullableMappedContext(null);

    context.put("aaa", 111);

    assertTrue(context.containsKey("aaa"));
    assertEquals(111, context.get("aaa"));

    assertFalse(context.containsKey("bbb"));
    assertNull(context.get("bbb"));
  }