Fix resolver-tests crate compile failure

crates/resolver-tests/src/lib.rs

@@ -1,6 +1,7 @@
 #![allow(clippy::many_single_char_names)]
 #![allow(clippy::needless_range_loop)] // false positives
 
+use std::borrow::Cow;
 use std::cell::RefCell;
 use std::cmp::PartialEq;
 use std::cmp::{max, min};
@@ -125,6 +126,14 @@ pub fn resolve_with_config_raw(
  used: HashSet<PackageId>,
  };
  impl<'a> Registry for MyRegistry<'a> {
+ fn prefetch(
+ &mut self,
+ _deps: &mut dyn ExactSizeIterator<Item = Cow<'_, Dependency>>,
+ ) -> CargoResult<()> {
+ // Doing nothing is a valid way to prefetch.
+ Ok(())
+ }
+
  fn query(
  &mut self,
  dep: &Dependency,