revset: add new graph iterator function for tests

I'm about to make `Revset::iter()` yield just `CommitId`s, but the
tests in `test_default_revset_graph_iterator.rs` need an `IndexEntry`
iterator so they can pass it into `RevsetGraphIterator::new()`. This
commits prepares for the change by adding a
`RevsetImpl::iter_graph_impl()` that returns `RevsetGraphIterator`,
keeping `InternalRevset` still hidden within the revset engine. We
could instead have made that (and `ToPredicateFn`) visible to tests. I
can't say which is better.

lib/src/default_index_store.rs

@@ -733,7 +733,8 @@ impl Index for MutableIndexImpl {
         repo: &'index dyn Repo,
         expression: &RevsetExpression,
     ) -> Result<Box<dyn Revset<'index> + 'index>, RevsetError> {
-        default_revset_engine::evaluate(repo, CompositeIndex(self), expression)
+        let revset_impl = default_revset_engine::evaluate(repo, CompositeIndex(self), expression)?;
+        Ok(Box::new(revset_impl))
     }
 }
 
@@ -1698,6 +1699,10 @@ impl ReadonlyIndexImpl {
         }))
     }
 
+    pub fn as_composite(&self) -> CompositeIndex {
+        CompositeIndex(self)
+    }
+
     fn name(&self) -> &str {
         &self.name
     }
@@ -1806,7 +1811,8 @@ impl Index for ReadonlyIndexImpl {
         repo: &'index dyn Repo,
         expression: &RevsetExpression,
     ) -> Result<Box<dyn Revset<'index> + 'index>, RevsetError> {
-        default_revset_engine::evaluate(repo, CompositeIndex(self), expression)
+        let revset_impl = default_revset_engine::evaluate(repo, CompositeIndex(self), expression)?;
+        Ok(Box::new(revset_impl))
     }
 }
 

lib/src/default_revset_engine.rs

@@ -51,7 +51,7 @@ trait InternalRevset<'index>: ToPredicateFn<'index> {
     fn iter(&self) -> Box<dyn Iterator<Item = IndexEntry<'index>> + '_>;
 }
 
-struct RevsetImpl<'index> {
+pub struct RevsetImpl<'index> {
     inner: Box<dyn InternalRevset<'index> + 'index>,
     index: CompositeIndex<'index>,
 }
@@ -66,6 +66,10 @@ impl<'index> RevsetImpl<'index> {
             index,
         }
     }
+
+    pub fn iter_graph_impl(&self) -> RevsetGraphIterator<'_, 'index> {
+        RevsetGraphIterator::new(self.inner.iter())
+    }
 }
 
 impl<'index> Revset<'index> for RevsetImpl<'index> {
@@ -491,9 +495,9 @@ pub fn evaluate<'index>(
     repo: &'index dyn Repo,
     index: CompositeIndex<'index>,
     expression: &RevsetExpression,
-) -> Result<Box<dyn Revset<'index> + 'index>, RevsetError> {
+) -> Result<RevsetImpl<'index>, RevsetError> {
     let internal_revset = internal_evaluate(repo, expression)?;
-    Ok(Box::new(RevsetImpl::new(internal_revset, index)))
+    Ok(RevsetImpl::new(internal_revset, index))
 }
 
 fn internal_evaluate<'index>(

lib/tests/test_default_revset_graph_iterator.rs

@@ -14,19 +14,22 @@
 
 use itertools::Itertools;
 use jujutsu_lib::commit::Commit;
-use jujutsu_lib::default_revset_graph_iterator::RevsetGraphIterator;
+use jujutsu_lib::default_index_store::ReadonlyIndexImpl;
+use jujutsu_lib::default_revset_engine::{evaluate, RevsetImpl};
 use jujutsu_lib::repo::Repo;
-use jujutsu_lib::revset::{Revset, RevsetExpression, RevsetGraphEdge};
+use jujutsu_lib::revset::{RevsetExpression, RevsetGraphEdge};
 use test_case::test_case;
 use testutils::{CommitGraphBuilder, TestRepo};
 
-fn revset_for_commits<'index>(
-    repo: &'index dyn Repo,
-    commits: &[&Commit],
-) -> Box<dyn Revset<'index> + 'index> {
-    RevsetExpression::commits(commits.iter().map(|commit| commit.id().clone()).collect())
-        .evaluate(repo)
-        .unwrap()
+fn revset_for_commits<'index>(repo: &'index dyn Repo, commits: &[&Commit]) -> RevsetImpl<'index> {
+    let index = repo
+        .index()
+        .as_any()
+        .downcast_ref::<ReadonlyIndexImpl>()
+        .unwrap();
+    let expression =
+        RevsetExpression::commits(commits.iter().map(|commit| commit.id().clone()).collect());
+    evaluate(repo, index.as_composite(), &expression).unwrap()
 }
 
 fn direct(commit: &Commit) -> RevsetGraphEdge {
@@ -66,7 +69,8 @@ fn test_graph_iterator_linearized(skip_transitive_edges: bool) {
     let root_commit = repo.store().root_commit();
 
     let revset = revset_for_commits(repo.as_ref(), &[&commit_a, &commit_d]);
-    let commits = RevsetGraphIterator::new(revset.iter())
+    let commits = revset
+        .iter_graph_impl()
         .set_skip_transitive_edges(skip_transitive_edges)
         .collect_vec();
     assert_eq!(commits.len(), 2);
@@ -105,7 +109,8 @@ fn test_graph_iterator_virtual_octopus(skip_transitive_edges: bool) {
     let root_commit = repo.store().root_commit();
 
     let revset = revset_for_commits(repo.as_ref(), &[&commit_a, &commit_b, &commit_c, &commit_f]);
-    let commits = RevsetGraphIterator::new(revset.iter())
+    let commits = revset
+        .iter_graph_impl()
         .set_skip_transitive_edges(skip_transitive_edges)
         .collect_vec();
     assert_eq!(commits.len(), 4);
@@ -155,7 +160,8 @@ fn test_graph_iterator_simple_fork(skip_transitive_edges: bool) {
     let root_commit = repo.store().root_commit();
 
     let revset = revset_for_commits(repo.as_ref(), &[&commit_a, &commit_c, &commit_e]);
-    let commits = RevsetGraphIterator::new(revset.iter())
+    let commits = revset
+        .iter_graph_impl()
         .set_skip_transitive_edges(skip_transitive_edges)
         .collect_vec();
     assert_eq!(commits.len(), 3);
@@ -195,7 +201,8 @@ fn test_graph_iterator_multiple_missing(skip_transitive_edges: bool) {
     let root_commit = repo.store().root_commit();
 
     let revset = revset_for_commits(repo.as_ref(), &[&commit_b, &commit_f]);
-    let commits = RevsetGraphIterator::new(revset.iter())
+    let commits = revset
+        .iter_graph_impl()
         .set_skip_transitive_edges(skip_transitive_edges)
         .collect_vec();
     assert_eq!(commits.len(), 2);
@@ -238,7 +245,8 @@ fn test_graph_iterator_edge_to_ancestor(skip_transitive_edges: bool) {
     let repo = tx.commit();
 
     let revset = revset_for_commits(repo.as_ref(), &[&commit_c, &commit_d, &commit_f]);
-    let commits = RevsetGraphIterator::new(revset.iter())
+    let commits = revset
+        .iter_graph_impl()
         .set_skip_transitive_edges(skip_transitive_edges)
         .collect_vec();
     assert_eq!(commits.len(), 3);
@@ -296,7 +304,8 @@ fn test_graph_iterator_edge_escapes_from_(skip_transitive_edges: bool) {
         repo.as_ref(),
         &[&commit_a, &commit_d, &commit_g, &commit_h, &commit_j],
     );
-    let commits = RevsetGraphIterator::new(revset.iter())
+    let commits = revset
+        .iter_graph_impl()
         .set_skip_transitive_edges(skip_transitive_edges)
         .collect_vec();
     assert_eq!(commits.len(), 5);