Rename matcher Contains

[ianlet]

Currently, the matcher Contains is used to assert that a Vec contains multiple elements.

Would it be more appropriate to rename it ContainsElements or ContainsAllOf and have another matcher Contains to assert the presence of a single element in a Vec?

Something like:

assert_that!(vec!(1, 2, 3), contains_elements(vec!(1, 2)));
// or
assert_that!(vec!(1, 2, 3), contains_all_of(vec!(1, 2)));

and

assert_that!(vec!(1, 2, 3), contains(1));

[ujh]

I wonder if it would be possible to implement From for Vec in such a way that contains would just convert a single element into a vector with one element. I'm not sure when I'll find the time to try that though.

[ianlet]

I'm still a beginner with Rust so I'm might be wrong, but I don't think this is possible to provide a generic implementation of From to convert to a Vec as it would probably collide with other implementations. I've just tried to impl<T> From<T> for Vec<T> but I got an error saying that T must be used as the type parameter for some local type.

On the other hand, what would be possible is changing contains signature to accept a generic T + Into<V<T>> but this is not really convenient as it will force the clients to implement the From trait for each of their types.

[ujh]

I guess you're right. I don't know Rust well enough to know if that would be possible or not either.

I'm OK with either name, but I would do it in two steps and just add contains_elements or contains_all_of first and deprecate contains. I would also add contain_elements/contain_all_of as an "alias" so that does_not(contain_all_of(...)) reads nicer.

Once that's in I would do a release and the new contains + (contain) can the go into master.

[povilasb]

I wonder if it would be possible to implement From for Vec in such a way that contains would just convert a single element into a vector with one element. I'm not sure when I'll find the time to try that though.

That might be possible in the future when RFC-1210 gets implemented.
If interested, you can track the status at rust-lang/rust#31844

[povilasb]

I do have motivation and some spare time, hence I could implement those changes :)

[ujh]

That would be pretty cool @povilasb!