1 use core::ops::DerefMut;
4 fn op1() -> Result<isize, &'static str> {
7 fn op2() -> Result<isize, &'static str> {
13 assert_eq!(op1().and(Ok(667)).unwrap(), 667);
14 assert_eq!(op1().and(Err::<i32, &'static str>("bad")).unwrap_err(), "bad");
16 assert_eq!(op2().and(Ok(667)).unwrap_err(), "sadface");
17 assert_eq!(op2().and(Err::<i32, &'static str>("bad")).unwrap_err(), "sadface");
22 assert_eq!(op1().and_then(|i| Ok::<isize, &'static str>(i + 1)).unwrap(), 667);
23 assert_eq!(op1().and_then(|_| Err::<isize, &'static str>("bad")).unwrap_err(), "bad");
25 assert_eq!(op2().and_then(|i| Ok::<isize, &'static str>(i + 1)).unwrap_err(), "sadface");
26 assert_eq!(op2().and_then(|_| Err::<isize, &'static str>("bad")).unwrap_err(), "sadface");
31 assert_eq!(op1().or(Ok::<_, &'static str>(667)).unwrap(), 666);
32 assert_eq!(op1().or(Err("bad")).unwrap(), 666);
34 assert_eq!(op2().or(Ok::<_, &'static str>(667)).unwrap(), 667);
35 assert_eq!(op2().or(Err("bad")).unwrap_err(), "bad");
40 assert_eq!(op1().or_else(|_| Ok::<isize, &'static str>(667)).unwrap(), 666);
41 assert_eq!(op1().or_else(|e| Err::<isize, &'static str>(e)).unwrap(), 666);
43 assert_eq!(op2().or_else(|_| Ok::<isize, &'static str>(667)).unwrap(), 667);
44 assert_eq!(op2().or_else(|e| Err::<isize, &'static str>(e)).unwrap_err(), "sadface");
49 assert!(Ok::<isize, isize>(1).map(|x| x + 1) == Ok(2));
50 assert!(Err::<isize, isize>(1).map(|x| x + 1) == Err(1));
54 fn test_impl_map_err() {
55 assert!(Ok::<isize, isize>(1).map_err(|x| x + 1) == Ok(1));
56 assert!(Err::<isize, isize>(1).map_err(|x| x + 1) == Err(2));
61 let v: Result<Vec<isize>, ()> = (0..0).map(|_| Ok::<isize, ()>(0)).collect();
62 assert!(v == Ok(vec![]));
64 let v: Result<Vec<isize>, ()> = (0..3).map(|x| Ok::<isize, ()>(x)).collect();
65 assert!(v == Ok(vec![0, 1, 2]));
67 let v: Result<Vec<isize>, isize> = (0..3).map(|x| if x > 1 { Err(x) } else { Ok(x) }).collect();
70 // test that it does not take more elements than it needs
71 let mut functions: [Box<dyn Fn() -> Result<(), isize>>; 3] =
72 [box || Ok(()), box || Err(1), box || panic!()];
74 let v: Result<Vec<()>, isize> = functions.iter_mut().map(|f| (*f)()).collect();
79 fn test_fmt_default() {
80 let ok: Result<isize, &'static str> = Ok(100);
81 let err: Result<isize, &'static str> = Err("Err");
83 let s = format!("{:?}", ok);
84 assert_eq!(s, "Ok(100)");
85 let s = format!("{:?}", err);
86 assert_eq!(s, "Err(\"Err\")");
91 let ok: Result<isize, &'static str> = Ok(100);
92 let ok_err: Result<isize, &'static str> = Err("Err");
94 assert_eq!(ok.unwrap_or(50), 100);
95 assert_eq!(ok_err.unwrap_or(50), 50);
100 let ok: Result<isize, isize> = Ok(100);
101 let err: Result<isize, isize> = Err(200);
103 assert_eq!(ok.into_ok_or_err(), 100);
104 assert_eq!(err.into_ok_or_err(), 200);
108 fn test_unwrap_or_else() {
109 fn handler(msg: &'static str) -> isize {
110 if msg == "I got this." { 50 } else { panic!("BadBad") }
113 let ok: Result<isize, &'static str> = Ok(100);
114 let ok_err: Result<isize, &'static str> = Err("I got this.");
116 assert_eq!(ok.unwrap_or_else(handler), 100);
117 assert_eq!(ok_err.unwrap_or_else(handler), 50);
122 pub fn test_unwrap_or_else_panic() {
123 fn handler(msg: &'static str) -> isize {
124 if msg == "I got this." { 50 } else { panic!("BadBad") }
127 let bad_err: Result<isize, &'static str> = Err("Unrecoverable mess.");
128 let _: isize = bad_err.unwrap_or_else(handler);
132 fn test_unwrap_unchecked() {
133 let ok: Result<isize, &'static str> = Ok(100);
134 assert_eq!(unsafe { ok.unwrap_unchecked() }, 100);
138 fn test_unwrap_err_unchecked() {
139 let ok_err: Result<isize, &'static str> = Err("Err");
140 assert_eq!(unsafe { ok_err.unwrap_err_unchecked() }, "Err");
144 pub fn test_expect_ok() {
145 let ok: Result<isize, &'static str> = Ok(100);
146 assert_eq!(ok.expect("Unexpected error"), 100);
149 #[should_panic(expected = "Got expected error: \"All good\"")]
150 pub fn test_expect_err() {
151 let err: Result<isize, &'static str> = Err("All good");
152 err.expect("Got expected error");
156 pub fn test_expect_err_err() {
157 let ok: Result<&'static str, isize> = Err(100);
158 assert_eq!(ok.expect_err("Unexpected ok"), 100);
161 #[should_panic(expected = "Got expected ok: \"All good\"")]
162 pub fn test_expect_err_ok() {
163 let err: Result<&'static str, isize> = Ok("All good");
164 err.expect_err("Got expected ok");
169 let ok: Result<isize, &'static str> = Ok(100);
170 let mut it = ok.iter();
171 assert_eq!(it.size_hint(), (1, Some(1)));
172 assert_eq!(it.next(), Some(&100));
173 assert_eq!(it.size_hint(), (0, Some(0)));
174 assert!(it.next().is_none());
175 assert_eq!((&ok).into_iter().next(), Some(&100));
177 let err: Result<isize, &'static str> = Err("error");
178 assert_eq!(err.iter().next(), None);
182 pub fn test_iter_mut() {
183 let mut ok: Result<isize, &'static str> = Ok(100);
184 for loc in ok.iter_mut() {
187 assert_eq!(ok, Ok(200));
191 assert_eq!(ok, Ok(300));
193 let mut err: Result<isize, &'static str> = Err("error");
194 for loc in err.iter_mut() {
197 assert_eq!(err, Err("error"));
201 pub fn test_unwrap_or_default() {
202 assert_eq!(op1().unwrap_or_default(), 666);
203 assert_eq!(op2().unwrap_or_default(), 0);
207 pub fn test_into_ok() {
208 fn infallible_op() -> Result<isize, !> {
212 assert_eq!(infallible_op().into_ok(), 666);
215 impl From<MyNeverToken> for ! {
216 fn from(never: MyNeverToken) -> ! {
221 fn infallible_op2() -> Result<isize, MyNeverToken> {
225 assert_eq!(infallible_op2().into_ok(), 667);
230 fn try_result_some() -> Option<u8> {
234 assert_eq!(try_result_some(), Some(1));
236 fn try_result_none() -> Option<u8> {
237 let val = Err(NoneError)?;
240 assert_eq!(try_result_none(), None);
242 fn try_result_ok() -> Result<u8, u8> {
243 let result: Result<u8, u8> = Ok(1);
247 assert_eq!(try_result_ok(), Ok(1));
249 fn try_result_err() -> Result<u8, u8> {
250 let result: Result<u8, u8> = Err(1);
254 assert_eq!(try_result_err(), Err(1));
258 fn test_result_as_deref() {
259 // &Result<T: Deref, E>::Ok(T).as_deref() ->
260 // Result<&T::Deref::Target, &E>::Ok(&*T)
261 let ref_ok = &Result::Ok::<&i32, u8>(&42);
262 let expected_result = Result::Ok::<&i32, &u8>(&42);
263 assert_eq!(ref_ok.as_deref(), expected_result);
265 let ref_ok = &Result::Ok::<String, u32>(String::from("a result"));
266 let expected_result = Result::Ok::<&str, &u32>("a result");
267 assert_eq!(ref_ok.as_deref(), expected_result);
269 let ref_ok = &Result::Ok::<Vec<i32>, u32>(vec![1, 2, 3, 4, 5]);
270 let expected_result = Result::Ok::<&[i32], &u32>([1, 2, 3, 4, 5].as_slice());
271 assert_eq!(ref_ok.as_deref(), expected_result);
273 // &Result<T: Deref, E>::Err(T).as_deref() ->
274 // Result<&T::Deref::Target, &E>::Err(&*E)
276 let ref_err = &Result::Err::<&u8, i32>(val);
277 let expected_result = Result::Err::<&u8, &i32>(&val);
278 assert_eq!(ref_err.as_deref(), expected_result);
280 let s = String::from("an error");
281 let ref_err = &Result::Err::<&u32, String>(s.clone());
282 let expected_result = Result::Err::<&u32, &String>(&s);
283 assert_eq!(ref_err.as_deref(), expected_result);
285 let v = vec![5, 4, 3, 2, 1];
286 let ref_err = &Result::Err::<&u32, Vec<i32>>(v.clone());
287 let expected_result = Result::Err::<&u32, &Vec<i32>>(&v);
288 assert_eq!(ref_err.as_deref(), expected_result);
292 fn test_result_as_deref_mut() {
293 // &mut Result<T: DerefMut, E>::Ok(T).as_deref_mut() ->
294 // Result<&mut T::DerefMut::Target, &mut E>::Ok(&mut *T)
296 let mut expected_val = 42;
297 let mut_ok = &mut Result::Ok::<&mut i32, u8>(&mut val);
298 let expected_result = Result::Ok::<&mut i32, &mut u8>(&mut expected_val);
299 assert_eq!(mut_ok.as_deref_mut(), expected_result);
301 let mut expected_string = String::from("a result");
302 let mut_ok = &mut Result::Ok::<String, u32>(expected_string.clone());
303 let expected_result = Result::Ok::<&mut str, &mut u32>(expected_string.deref_mut());
304 assert_eq!(mut_ok.as_deref_mut(), expected_result);
306 let mut expected_vec = vec![1, 2, 3, 4, 5];
307 let mut_ok = &mut Result::Ok::<Vec<i32>, u32>(expected_vec.clone());
308 let expected_result = Result::Ok::<&mut [i32], &mut u32>(expected_vec.as_mut_slice());
309 assert_eq!(mut_ok.as_deref_mut(), expected_result);
311 // &mut Result<T: DerefMut, E>::Err(T).as_deref_mut() ->
312 // Result<&mut T, &mut E>::Err(&mut *E)
314 let mut_err = &mut Result::Err::<&mut u8, i32>(val);
315 let expected_result = Result::Err::<&mut u8, &mut i32>(&mut val);
316 assert_eq!(mut_err.as_deref_mut(), expected_result);
318 let mut expected_string = String::from("an error");
319 let mut_err = &mut Result::Err::<&mut u32, String>(expected_string.clone());
320 let expected_result = Result::Err::<&mut u32, &mut String>(&mut expected_string);
321 assert_eq!(mut_err.as_deref_mut(), expected_result);
323 let mut expected_vec = vec![5, 4, 3, 2, 1];
324 let mut_err = &mut Result::Err::<&mut u32, Vec<i32>>(expected_vec.clone());
325 let expected_result = Result::Err::<&mut u32, &mut Vec<i32>>(&mut expected_vec);
326 assert_eq!(mut_err.as_deref_mut(), expected_result);
331 // test that the methods of `Result` are usable in a const context
333 const RESULT: Result<usize, bool> = Ok(32);
335 const REF: Result<&usize, &bool> = RESULT.as_ref();
336 assert_eq!(REF, Ok(&32));
338 const IS_OK: bool = RESULT.is_ok();
341 const IS_ERR: bool = RESULT.is_err();
346 fn result_opt_conversions() {
347 #[derive(Copy, Clone, Debug, PartialEq)]
350 fn try_num(x: i32) -> Result<i32, BadNumErr> {
351 if x <= 5 { Ok(x + 1) } else { Err(BadNumErr) }
354 type ResOpt = Result<Option<i32>, BadNumErr>;
355 type OptRes = Option<Result<i32, BadNumErr>>;
357 let mut x: ResOpt = Ok(Some(5));
358 let mut y: OptRes = Some(Ok(5));
359 assert_eq!(x, y.transpose());
360 assert_eq!(x.transpose(), y);
364 assert_eq!(x, y.transpose());
365 assert_eq!(x.transpose(), y);
368 y = Some(Err(BadNumErr));
369 assert_eq!(x, y.transpose());
370 assert_eq!(x.transpose(), y);
372 let res: Result<Vec<i32>, BadNumErr> = (0..10)
375 Ok(if y % 2 == 0 { Some(y - 1) } else { None })
377 .filter_map(Result::transpose)
380 assert_eq!(res, Err(BadNumErr))