Implement WriteTo trait for gix::Blob

gix/src/object/impls.rs

@@ -150,6 +150,23 @@ impl std::fmt::Debug for Object<'_> {
     }
 }
 
+/// Note that the `data` written here might not correspond to the `id` of the `Blob` anymore if it was modified.
+/// Also, this is merely for convenience when writing empty blobs to the ODB. For writing any blob, use
+/// [`Repository::write_blob()`](crate::Repository::write_blob()).
+impl gix_object::WriteTo for Blob<'_> {
+    fn write_to(&self, out: &mut dyn std::io::Write) -> std::io::Result<()> {
+        out.write_all(&self.data)
+    }
+
+    fn kind(&self) -> gix_object::Kind {
+        gix_object::Kind::Blob
+    }
+
+    fn size(&self) -> u64 {
+        self.data.len() as u64
+    }
+}
+
 /// In conjunction with the handles free list, leaving an empty Vec in place of the original causes it to not be
 /// returned to the free list.
 fn steal_from_freelist(data: &mut Vec<u8>) -> Vec<u8> {

gix/tests/gix/repository/object.rs

@@ -262,7 +262,7 @@ mod write_object {
         let oid = repo.write_object(gix::objs::TreeRef::empty())?;
         assert_eq!(
             oid,
-            gix::hash::ObjectId::empty_tree(repo.object_hash()),
+            repo.object_hash().empty_tree(),
             "it produces a well-known empty tree id"
         );
         Ok(())
@@ -277,7 +277,7 @@ mod write_object {
             time: Default::default(),
         };
         let commit = gix::objs::Commit {
-            tree: gix::hash::ObjectId::empty_tree(repo.object_hash()),
+            tree: repo.object_hash().empty_tree(),
             author: actor.clone(),
             committer: actor,
             parents: Default::default(),
@@ -292,6 +292,21 @@ mod write_object {
         );
         Ok(())
     }
+
+    #[test]
+    fn blob_write_to_implementation() -> crate::Result {
+        let repo = empty_bare_in_memory_repo()?;
+        let blob = repo.empty_blob();
+
+        // Create a blob directly to test our WriteTo implementation
+        let actual_id = repo.write_object(&blob)?;
+        let actual_blob = repo.find_object(actual_id)?.into_blob();
+        assert_eq!(actual_id, repo.object_hash().empty_blob());
+
+        assert_eq!(actual_blob.data, blob.data);
+
+        Ok(())
+    }
 }
 
 mod write_blob {