public void testBuilderWithExpectedKeysNegative() {
    assertThrows(
        IllegalArgumentException.class, () -> ImmutableMultimap.builderWithExpectedKeys(-1));
  }

  public void testBuilderWithExpectedKeysZero() {
    ImmutableMultimap.Builder<String, String> builder =
        ImmutableMultimap.builderWithExpectedKeys(0);
    builder.put("key", "value");
    assertThat(builder.build().entries()).containsExactly(immutableEntry("key", "value"));
  }