无法将“& Thing"与"Thing"进行比较 [英] Can't compare `&Thing` with `Thing`
问题描述
我知道错误的含义,但我无法解决.我正在使用mockers
来测试我的工作,尝试验证赋予模拟特征的函数的struct参数时,我陷入了困境.简化的代码:
I know what the error means, but I can't fix it. I'm using mockers
to test my work and I got stuck when trying to verify the struct parameter which was given to a mocked trait's function. The simplified code:
#[cfg(test)]
extern crate mockers;
#[cfg(test)]
extern crate mockers_derive;
#[cfg(test)]
use mockers_derive::mocked;
#[derive(Ord, PartialOrd, Eq, PartialEq, Debug)]
pub struct Thing {
pub key: String,
pub class: String,
}
#[cfg_attr(test, mocked)]
pub trait DaoTrait {
fn get(&self, thing: &Thing) -> String;
}
struct DataService {
dao: Box<DaoTrait>,
}
impl DataService {
pub fn get(&self, thing: &Thing) -> String {
self.dao.get(thing)
}
}
#[cfg(test)]
mod test {
use super::*;
use mockers::matchers::eq;
use mockers::Scenario;
#[test]
fn my_test() {
use mockers::matchers::check;
let scenario = Scenario::new();
let mut dao = scenario.create_mock_for::<DaoTrait>();
let thing = Thing {
key: "my test".to_string(),
class: "for test".to_string(),
};
scenario.expect(
dao.get_call(check(|t: &Thing| t.to_owned() == thing))
.and_return("hello".to_string()),
);
let testee = DataService { dao: Box::new(dao) };
let rtn = testee.get(&thing);
assert_eq!(rtn, "hello");
}
}
我得到了错误:
warning: unused import: `mockers::matchers::eq`
--> src/main.rs:33:9
|
33 | use mockers::matchers::eq;
| ^^^^^^^^^^^^^^^^^^^^^
|
= note: #[warn(unused_imports)] on by default
error[E0277]: can't compare `&Thing` with `Thing`
--> src/main.rs:47:57
|
47 | dao.get_call(check(|t: &Thing| t.to_owned() == thing))
| ^^ no implementation for `&Thing == Thing`
|
= help: the trait `std::cmp::PartialEq<Thing>` is not implemented for `&Thing`
error[E0277]: the trait bound `mockers::matchers::BoolFnMatchArg<Thing, [closure@src/main.rs:47:32: 47:65 thing:_]>: mockers::MatchArg<&Thing>` is not satisfied
--> src/main.rs:47:17
|
47 | dao.get_call(check(|t: &Thing| t.to_owned() == thing))
| ^^^^^^^^ the trait `mockers::MatchArg<&Thing>` is not implemented for `mockers::matchers::BoolFnMatchArg<Thing, [closure@src/main.rs:47:32: 47:65 thing:_]>`
|
= help: the following implementations were found:
<mockers::matchers::BoolFnMatchArg<T, F> as mockers::MatchArg<T>>
我查看了check
的源代码:
pub fn check<T, F: Fn(&T) -> bool>(f: F) -> BoolFnMatchArg<T, F> {
BoolFnMatchArg { func: f, _phantom: PhantomData }
}
我认为我给出的闭包|t: &Thing| t.to_owned() == thing
是正确的.我也尝试了以下关闭,但没有一个起作用.
I think the closure |t: &Thing| t.to_owned() == thing
I had given is right. I also tried the following closures, but none of them worked.
|t: &Thing| t == &thing
|t: &Thing| *t == thing
|t: Thing| t == thing
The Cargo.toml:
The Cargo.toml:
[dev-dependencies]
mockers = "0.12.1"
mockers_derive = "0.12.1"
推荐答案
您无法使用默认派生的PartialEq
将Thing
与&Thing
进行比较:
You cannot compare a Thing
to a &Thing
using the default derivation of PartialEq
:
#[derive(Debug, PartialEq)]
struct Thing(String);
fn main() {
let t_val = Thing(String::new());
let t_ref = &t_val;
t_val == t_ref;
}
error[E0308]: mismatched types
--> src/main.rs:8:14
|
8 | t_val == t_ref;
| ^^^^^ expected struct `Thing`, found &Thing
|
= note: expected type `Thing`
found type `&Thing`
要修复该错误,您需要执行以下两项操作之一:
To fix that error, you need to do one of two things:
-
匹配参考级别:
Match the reference level:
-
t_val == *t_ref
&t_val == t_ref
对引用数量不匹配的实现相等:
Implement equality for a mismatched number of references:
impl<'a> PartialEq<&'a Thing> for Thing {
fn eq(&self, other: &&'a Thing) -> bool {
self == *other
}
}
impl<'a> PartialEq<Thing> for &'a Thing {
fn eq(&self, other: &Thing) -> bool {
*self == other
}
}
但是,这些都不能解决您的实际问题.您已经误解了嘲笑库的工作方式;您的闭包引用错误的级别,并且需要对值的所有权进行比较:
However, none of that solves your actual problem. You've misunderstood how the mockers library works; your closure is taking the wrong level of reference, and it needs to take ownership of the value to compare:
let expected_thing = thing.clone();
scenario.expect(
dao.get_call(check(move |t: &&Thing| t == &&expected_thing))
.and_return("hello".to_string()),
);
这篇关于无法将“& Thing"与"Thing"进行比较的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!