warning: variable does not need to be mutable

[IvanaGyro]

rust-koans/src/koans/vec.rs

Lines 105 to 112 in c6e8193

	// We created an empty Vec in our first example,
	// now let's check if a Vec is empty
	#[test]
	fn empty_vecs() {
	let mut vector = vec![""; 0];
	assert!(vector.is_empty()); // should return true
	assert!(!vector.is_empty()); // should return false
	}

The case above raise a warning:

warning: variable does not need to be mutable
   --> src/koans/vec.rs:109:9
    |
109 |     let mut vector = vec![""; 0];
    |         ----^^^^^^
    |         |
    |         help: remove this `mut`
    |
    = note: `#[warn(unused_mut)]` on by default

The versions I am running:

• cargo 1.42.0 (86334295e 2020-01-31)
• rustc 1.42.0 (b8cedc004 2020-03-09)

[IvanaGyro]

What's more, that case fails the test.
Maybe it should be

 // We created an empty Vec in our first example, 
 // now let's check if a Vec is empty 
 #[test] 
 fn empty_vecs() { 
     let vector = vec![""; 0]; 
     assert!(vector.is_empty()); // should return true 
     // assert!(!vector.is_empty()); // should return false 
 } 

Thanks for this project.

[crazymykl]

The idea is that one is supposed to add code to make the vec non-empty between the two assertions. As in your other issue, a __; would make this more clear.