使用 assert_eq 或打印大型固定大小的数组不起作用

Question

我已经编写了一些测试，我需要断言两个数组相等。有些数组是[u8; 48]，有些是[u8; 188]：

#[test]
fn mul() {
    let mut t1: [u8; 48] = [0; 48];
    let t2: [u8; 48] = [0; 48];

    // some computation goes here.

    assert_eq!(t1, t2, "\nExpected\n{:?}\nfound\n{:?}", t2, t1);
}

我在这里遇到多个错误：

error[E0369]: binary operation `==` cannot be applied to type `[u8; 48]`
 --> src/main.rs:8:5
  |
8 |     assert_eq!(t1, t2, "\nExpected\n{:?}\nfound\n{:?}", t2, t1);
  |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  |
  = note: an implementation of `std::cmp::PartialEq` might be missing for `[u8; 48]`
  = note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)

error[E0277]: the trait bound `[u8; 48]: std::fmt::Debug` is not satisfied
 --> src/main.rs:8:57
  |
8 |     assert_eq!(t1, t2, "\nExpected\n{:?}\nfound\n{:?}", t2, t1);
  |                                                         ^^ `[u8; 48]` cannot be formatted using `:?`; if it is defined in your crate, add `#[derive(Debug)]` or manually implement it
  |
  = help: the trait `std::fmt::Debug` is not implemented for `[u8; 48]`
  = note: required by `std::fmt::Debug::fmt`

尝试将它们打印为像 t2[..] 或 t1[..] 这样的切片似乎不起作用。

如何将assert 与这些数组一起使用并打印它们？

Answer 1

使用Iterator::eq，可以比较任何可以转换为相等迭代器的东西：

let mut t1: [u8; 48] = [0; 48];
let t2: [u8; 48] = [0; 48];
assert!(t1.iter().eq(t2.iter()));

Answer 2

你可以把它们变成Vecs。

fn main() {
    let a: [u8; 3] = [0, 1, 2];
    let b: [u8; 3] = [2, 3, 4];
    let c: [u8; 3] = [0, 1, 2];

    let va: Vec<u8> = a.to_vec();
    let vb: Vec<u8> = b.to_vec();
    let vc: Vec<u8> = c.to_vec();

    println!("va==vb {}", va == vb);
    println!("va==vc {}", va == vc);
    println!("vb==vc {}", vb == vc);
}

Answer 3

使用切片

作为一种解决方法，您可以只使用 &t1[..]（而不是 t1[..]）将数组制作成切片。您必须为比较和格式化这样做。

assert_eq!(&t1[..], &t2[..], "\nExpected\n{:?}\nfound\n{:?}", &t2[..], &t1[..]);

或

assert_eq!(t1[..], t2[..], "\nExpected\n{:?}\nfound\n{:?}", &t2[..], &t1[..]);

直接格式化数组

理想情况下，原始代码应该可以编译，但现在还不行。原因是标准库implements common traits（如Eq和Debug）对于最多只有32个元素的数组，由于lack of const generics。

因此，您可以比较和格式化较短的数组，例如：

let t1: [u8; 32] = [0; 32];
let t2: [u8; 32] = [1; 32];
assert_eq!(t1, t2, "\nExpected\n{:?}\nfound\n{:?}", t2, t1);

Answer 4

对于比较部分，您可以将数组转换为迭代器并按元素进行比较。

assert_eq!(t1.len(), t2.len(), "Arrays don't have the same length");
assert!(t1.iter().zip(t2.iter()).all(|(a,b)| a == b), "Arrays are not equal");