public void testEmptyBuilder() {
    ImmutableMap<String, Integer> map = new Builder<String, Integer>().buildOrThrow();
    assertEquals(Collections.<String, Integer>emptyMap(), map);
  }

  public void testSingletonBuilder() {
    ImmutableMap<String, Integer> map = new Builder<String, Integer>().put("one", 1).buildOrThrow();
    assertMapEquals(map, "one", 1);
  }

  public void testBuilder() {