how to mock a trait with bounds?

[rbtcollins]

e.g.

#[cfg_attr(test, automock)]
pub trait ExtendedIterator: Iterator<Item = ()> + Send + Sync {}

->

error[E0277]: `MockExtendedIterator` is not an iterator
  --> src/compile_schemas.rs:26:18
   |
26 | pub(crate) trait ExtendedIterator: Iterator<Item = ()> + Send + Sync {}
   |                  ^^^^^^^^^^^^  ------------------- required by this bound in `module::ExtendedIterator`
   |                  |
   |                  `MockExtendedIterator` is not an iterator
   |
   = help: the trait `Iterator` is not implemented for `MockExtendedIterator`

[asomers]

You can't use #[automock] for a trait with bounds. You need to use mock! instead. Like this: https://docs.rs/mockall/0.10.2/mockall/#multiple-and-inherited-traits .

[rbtcollins]

... this actually works..

fn next(&mut self) -> Option<<MockExtendedIterator as Iterator>::Item>;

[asomers]

So everything good now?

[rbtcollins]

There's that error:

error[E0223]: ambiguous associated type
  --> src/compile_schemas.rs:67:9
   |
67 | /         ExtendedIterator {}
...  |
72| |    impl Iterator for ExtendedIterator {
73 | |             type Item=();
74 | |             fn next(&mut self) -> Option<Self::Item>;
   | |___________________________________________________^ help: use fully-qualified syntax: `<compile_schemas::test::MockExtendedIterator as Trait>::Item`

error: aborting due to previous error

For more information about this error, try `rustc --explain E0223`.

which there is a workaround:

-fn next(&mut self) -> Option<Self::Item>;
+fn next(&mut self) -> Option<<MockExtendedIterator as Iterator>::Item>;

but I haven't seen any docs saying that that is needed, or whether thats considered a bug.

That said, I am able to use the software, so its up to you whether you close this, make a bug from it, whatever.

[asomers]

Wait, are you mixing up your two problems? The "MockExtendedIterator is not an iterator" was caused by attempting to use #[automock] with trait bounds. Using "::Item" fixed your "ambiguous associated type" problem.

[rbtcollins]

sorry yes. let me edit that. Using the MockExtendedIterator::Item fixed it, but I don't recall seeing anywhere in the docs the idea of using the Mock as a name inside the mock! clause, even though it obviously works.