#[macro_use] extern crate derive_builder; #[derive(Debug, PartialEq, Default, Builder, Clone)] #[builder(name = "MyBuilder")] struct Lorem { ipsum: &'static str, pub dolor: Option<&'static str>, pub sit: i32, amet: bool, } #[test] fn error_if_uninitialized() { let error = MyBuilder::default().build().unwrap_err(); assert_eq!(&error.to_string(), "`ipsum` must be initialized"); } #[test] fn builder_test() { let x: Lorem = MyBuilder::default() .ipsum("lorem") .dolor(Some("dolor")) .sit(42) .amet(true) .build() .unwrap(); assert_eq!( x, Lorem { ipsum: "lorem", dolor: Some("dolor"), sit: 42, amet: true, } ); }