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::new(|| Ok(())), Box::new(|| Err(1)), Box::new(|| 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);
229 pub fn test_into_err() {
230 fn until_error_op() -> Result<!, isize> {
234 assert_eq!(until_error_op().into_err(), 666);
237 impl From<MyNeverToken> for ! {
238 fn from(never: MyNeverToken) -> ! {
243 fn until_error_op2() -> Result<MyNeverToken, isize> {
247 assert_eq!(until_error_op2().into_err(), 667);
252 fn try_result_ok() -> Result<u8, u32> {
253 let result: Result<u8, u8> = Ok(1);
257 assert_eq!(try_result_ok(), Ok(1));
259 fn try_result_err() -> Result<u8, u32> {
260 let result: Result<u8, u8> = Err(1);
264 assert_eq!(try_result_err(), Err(1));
268 fn test_result_as_deref() {
269 // &Result<T: Deref, E>::Ok(T).as_deref() ->
270 // Result<&T::Deref::Target, &E>::Ok(&*T)
271 let ref_ok = &Result::Ok::<&i32, u8>(&42);
272 let expected_result = Result::Ok::<&i32, &u8>(&42);
273 assert_eq!(ref_ok.as_deref(), expected_result);
275 let ref_ok = &Result::Ok::<String, u32>(String::from("a result"));
276 let expected_result = Result::Ok::<&str, &u32>("a result");
277 assert_eq!(ref_ok.as_deref(), expected_result);
279 let ref_ok = &Result::Ok::<Vec<i32>, u32>(vec![1, 2, 3, 4, 5]);
280 let expected_result = Result::Ok::<&[i32], &u32>([1, 2, 3, 4, 5].as_slice());
281 assert_eq!(ref_ok.as_deref(), expected_result);
283 // &Result<T: Deref, E>::Err(T).as_deref() ->
284 // Result<&T::Deref::Target, &E>::Err(&*E)
286 let ref_err = &Result::Err::<&u8, i32>(val);
287 let expected_result = Result::Err::<&u8, &i32>(&val);
288 assert_eq!(ref_err.as_deref(), expected_result);
290 let s = String::from("an error");
291 let ref_err = &Result::Err::<&u32, String>(s.clone());
292 let expected_result = Result::Err::<&u32, &String>(&s);
293 assert_eq!(ref_err.as_deref(), expected_result);
295 let v = vec![5, 4, 3, 2, 1];
296 let ref_err = &Result::Err::<&u32, Vec<i32>>(v.clone());
297 let expected_result = Result::Err::<&u32, &Vec<i32>>(&v);
298 assert_eq!(ref_err.as_deref(), expected_result);
302 fn test_result_as_deref_mut() {
303 // &mut Result<T: DerefMut, E>::Ok(T).as_deref_mut() ->
304 // Result<&mut T::DerefMut::Target, &mut E>::Ok(&mut *T)
306 let mut expected_val = 42;
307 let mut_ok = &mut Result::Ok::<&mut i32, u8>(&mut val);
308 let expected_result = Result::Ok::<&mut i32, &mut u8>(&mut expected_val);
309 assert_eq!(mut_ok.as_deref_mut(), expected_result);
311 let mut expected_string = String::from("a result");
312 let mut_ok = &mut Result::Ok::<String, u32>(expected_string.clone());
313 let expected_result = Result::Ok::<&mut str, &mut u32>(expected_string.deref_mut());
314 assert_eq!(mut_ok.as_deref_mut(), expected_result);
316 let mut expected_vec = vec![1, 2, 3, 4, 5];
317 let mut_ok = &mut Result::Ok::<Vec<i32>, u32>(expected_vec.clone());
318 let expected_result = Result::Ok::<&mut [i32], &mut u32>(expected_vec.as_mut_slice());
319 assert_eq!(mut_ok.as_deref_mut(), expected_result);
321 // &mut Result<T: DerefMut, E>::Err(T).as_deref_mut() ->
322 // Result<&mut T, &mut E>::Err(&mut *E)
324 let mut_err = &mut Result::Err::<&mut u8, i32>(val);
325 let expected_result = Result::Err::<&mut u8, &mut i32>(&mut val);
326 assert_eq!(mut_err.as_deref_mut(), expected_result);
328 let mut expected_string = String::from("an error");
329 let mut_err = &mut Result::Err::<&mut u32, String>(expected_string.clone());
330 let expected_result = Result::Err::<&mut u32, &mut String>(&mut expected_string);
331 assert_eq!(mut_err.as_deref_mut(), expected_result);
333 let mut expected_vec = vec![5, 4, 3, 2, 1];
334 let mut_err = &mut Result::Err::<&mut u32, Vec<i32>>(expected_vec.clone());
335 let expected_result = Result::Err::<&mut u32, &mut Vec<i32>>(&mut expected_vec);
336 assert_eq!(mut_err.as_deref_mut(), expected_result);
341 // test that the methods of `Result` are usable in a const context
343 const RESULT: Result<usize, bool> = Ok(32);
345 const REF: Result<&usize, &bool> = RESULT.as_ref();
346 assert_eq!(REF, Ok(&32));
348 const IS_OK: bool = RESULT.is_ok();
351 const IS_ERR: bool = RESULT.is_err();
356 const fn result_const_mut() {
357 let mut result: Result<usize, bool> = Ok(32);
360 let as_mut = result.as_mut();
363 Err(_) => unreachable!(),
367 let mut result_err: Result<usize, bool> = Err(false);
370 let as_mut = result_err.as_mut();
372 Ok(_) => unreachable!(),
379 fn result_opt_conversions() {
380 #[derive(Copy, Clone, Debug, PartialEq)]
383 fn try_num(x: i32) -> Result<i32, BadNumErr> {
384 if x <= 5 { Ok(x + 1) } else { Err(BadNumErr) }
387 type ResOpt = Result<Option<i32>, BadNumErr>;
388 type OptRes = Option<Result<i32, BadNumErr>>;
390 let mut x: ResOpt = Ok(Some(5));
391 let mut y: OptRes = Some(Ok(5));
392 assert_eq!(x, y.transpose());
393 assert_eq!(x.transpose(), y);
397 assert_eq!(x, y.transpose());
398 assert_eq!(x.transpose(), y);
401 y = Some(Err(BadNumErr));
402 assert_eq!(x, y.transpose());
403 assert_eq!(x.transpose(), y);
405 let res: Result<Vec<i32>, BadNumErr> = (0..10)
408 Ok(if y % 2 == 0 { Some(y - 1) } else { None })
410 .filter_map(Result::transpose)
413 assert_eq!(res, Err(BadNumErr))
417 fn result_try_trait_v2_branch() {
418 use core::num::NonZeroU32;
419 use core::ops::{ControlFlow::*, Try};
420 assert_eq!(Ok::<i32, i32>(4).branch(), Continue(4));
421 assert_eq!(Err::<i32, i32>(4).branch(), Break(Err(4)));
422 let one = NonZeroU32::new(1).unwrap();
423 assert_eq!(Ok::<(), NonZeroU32>(()).branch(), Continue(()));
424 assert_eq!(Err::<(), NonZeroU32>(one).branch(), Break(Err(one)));
425 assert_eq!(Ok::<NonZeroU32, ()>(one).branch(), Continue(one));
426 assert_eq!(Err::<NonZeroU32, ()>(()).branch(), Break(Err(())));