tests: call num_commits() on specific implementation

This removes the last calls to `Index::num_commits()`.

lib/tests/test_index.rs

@@ -17,7 +17,7 @@ use std::sync::Arc;
 use jujutsu_lib::backend::CommitId;
 use jujutsu_lib::commit::Commit;
 use jujutsu_lib::commit_builder::CommitBuilder;
-use jujutsu_lib::default_index_store::ReadonlyIndexImpl;
+use jujutsu_lib::default_index_store::{MutableIndexImpl, ReadonlyIndexImpl};
 use jujutsu_lib::index::Index;
 use jujutsu_lib::repo::{MutableRepo, ReadonlyRepo, Repo};
 use jujutsu_lib::settings::UserSettings;
@@ -45,7 +45,7 @@ fn test_index_commits_empty_repo(use_git: bool) {
     let test_repo = TestRepo::init(use_git);
     let repo = &test_repo.repo;
 
-    let index = repo.index();
+    let index = as_readonly_impl(repo);
     // There should be just the root commit
     assert_eq!(index.num_commits(), 1);
 
@@ -87,7 +87,7 @@ fn test_index_commits_standard_cases(use_git: bool) {
     let commit_h = graph_builder.commit_with_parents(&[&commit_e]);
     let repo = tx.commit();
 
-    let index = as_index_impl(&repo);
+    let index = as_readonly_impl(&repo);
     // There should be the root commit, plus 8 more
     assert_eq!(index.num_commits(), 1 + 8);
 
@@ -147,7 +147,7 @@ fn test_index_commits_criss_cross(use_git: bool) {
     }
     let repo = tx.commit();
 
-    let index = as_index_impl(&repo);
+    let index = as_readonly_impl(&repo);
     // There should the root commit, plus 2 for each generation
     assert_eq!(index.num_commits(), 1 + 2 * (num_generations as u32));
 
@@ -293,7 +293,7 @@ fn test_index_commits_previous_operations(use_git: bool) {
     std::fs::create_dir(&index_operations_dir).unwrap();
 
     let repo = load_repo_at_head(&settings, repo.repo_path());
-    let index = as_index_impl(&repo);
+    let index = as_readonly_impl(&repo);
     // There should be the root commit, plus 3 more
     assert_eq!(index.num_commits(), 1 + 3);
 
@@ -330,7 +330,7 @@ fn test_index_commits_incremental(use_git: bool) {
         .unwrap();
     let repo = tx.commit();
 
-    let index = repo.index();
+    let index = as_readonly_impl(&repo);
     // There should be the root commit, plus 1 more
     assert_eq!(index.num_commits(), 1 + 1);
 
@@ -344,7 +344,7 @@ fn test_index_commits_incremental(use_git: bool) {
     tx.commit();
 
     let repo = load_repo_at_head(&settings, repo.repo_path());
-    let index = as_index_impl(&repo);
+    let index = as_readonly_impl(&repo);
     // There should be the root commit, plus 3 more
     assert_eq!(index.num_commits(), 1 + 3);
 
@@ -382,14 +382,14 @@ fn test_index_commits_incremental_empty_transaction(use_git: bool) {
         .unwrap();
     let repo = tx.commit();
 
-    let index = repo.index();
+    let index = as_readonly_impl(&repo);
     // There should be the root commit, plus 1 more
     assert_eq!(index.num_commits(), 1 + 1);
 
     repo.start_transaction(&settings, "test").commit();
 
     let repo = load_repo_at_head(&settings, repo.repo_path());
-    let index = as_index_impl(&repo);
+    let index = as_readonly_impl(&repo);
     // There should be the root commit, plus 1 more
     assert_eq!(index.num_commits(), 1 + 1);
 
@@ -426,11 +426,11 @@ fn test_index_commits_incremental_already_indexed(use_git: bool) {
     let repo = tx.commit();
 
     assert!(repo.index().has_id(commit_a.id()));
-    assert_eq!(repo.index().num_commits(), 1 + 1);
+    assert_eq!(as_readonly_impl(&repo).num_commits(), 1 + 1);
     let mut tx = repo.start_transaction(&settings, "test");
     let mut_repo = tx.mut_repo();
     mut_repo.add_head(&commit_a);
-    assert_eq!(mut_repo.index().num_commits(), 1 + 1);
+    assert_eq!(as_mutable_impl(mut_repo).num_commits(), 1 + 1);
 }
 
 #[must_use]
@@ -446,7 +446,7 @@ fn create_n_commits(
     tx.commit()
 }
 
-fn as_index_impl(repo: &Arc<ReadonlyRepo>) -> &ReadonlyIndexImpl {
+fn as_readonly_impl(repo: &Arc<ReadonlyRepo>) -> &ReadonlyIndexImpl {
     repo.readonly_index()
         .as_index()
         .as_any()
@@ -454,8 +454,15 @@ fn as_index_impl(repo: &Arc<ReadonlyRepo>) -> &ReadonlyIndexImpl {
         .unwrap()
 }
 
+fn as_mutable_impl(repo: &MutableRepo) -> &MutableIndexImpl {
+    repo.index()
+        .as_any()
+        .downcast_ref::<MutableIndexImpl>()
+        .unwrap()
+}
+
 fn commits_by_level(repo: &Arc<ReadonlyRepo>) -> Vec<u32> {
-    as_index_impl(repo)
+    as_readonly_impl(repo)
         .stats()
         .levels
         .iter()
@@ -536,7 +543,7 @@ fn test_index_store_type(use_git: bool) {
     let test_repo = TestRepo::init(use_git);
     let repo = &test_repo.repo;
 
-    assert_eq!(repo.index().num_commits(), 1);
+    assert_eq!(as_readonly_impl(repo).num_commits(), 1);
     let index_store_type_path = repo.repo_path().join("index").join("type");
     assert_eq!(
         std::fs::read_to_string(&index_store_type_path).unwrap(),
@@ -550,5 +557,5 @@ fn test_index_store_type(use_git: bool) {
         std::fs::read_to_string(&index_store_type_path).unwrap(),
         "default"
     );
-    assert_eq!(repo.index().num_commits(), 1);
+    assert_eq!(as_readonly_impl(&repo).num_commits(), 1);
 }