public void Add_Should_Throw_When_SetThingTypeIsNotCalled()
 => Assert.Throws <InvalidOperationException>(() => _builder.Add(Substitute.For <PropertyInfo>(),
                                                                 new JsonSchema(Substitute.For <IJsonSchema>(), null, JsonType.String,
                                                                                _fixture.Create <string>(), _fixture.Create <bool>())));