From c34d07c7af2db014ffdb426463195b974852b99a Mon Sep 17 00:00:00 2001
From: antiochp <30642645+antiochp@users.noreply.github.com>
Date: Fri, 20 Mar 2020 21:53:00 +0000
Subject: [PATCH] some test coverage for output_pos_list

---
 chain/src/store.rs                   |  37 +++++++---
 chain/src/types.rs                   |   2 +-
 chain/tests/store_output_pos_list.rs | 104 +++++++++++++++++++++++++++
 store/src/lmdb.rs                    |   3 +
 4 files changed, 137 insertions(+), 9 deletions(-)
 create mode 100644 chain/tests/store_output_pos_list.rs

diff --git a/chain/src/store.rs b/chain/src/store.rs
index 4d2abfd364..f72fd27fcf 100644
--- a/chain/src/store.rs
+++ b/chain/src/store.rs
@@ -64,9 +64,7 @@ impl ChainStore {
 			db: db_with_version,
 		}
 	}
-}
 
-impl ChainStore {
 	/// The current chain head.
 	pub fn head(&self) -> Result<Tip, Error> {
 		option_to_not_found(self.db.get_ser(&[HEAD_PREFIX]), || "HEAD".to_owned())
@@ -437,6 +435,7 @@ impl Readable for OutputPosEntryVariant {
 	}
 }
 
+#[derive(Copy, Clone, Debug, PartialEq)]
 pub enum OutputPosList {
 	Unique { pos: OutputPos },
 	Multi { head: u64, tail: u64 },
@@ -553,12 +552,34 @@ impl OutputPosList {
 				batch.db.put_ser(&Self::list_key(commit), &list)?;
 			}
 			Some(OutputPosList::Multi { head, tail }) => {
-				// lookup entry for current head
-				// create new middle based on current head
-				// save new middle to db
-				// create new head based on new_pos
-				// save updated head to db
-				// save list itself with head and tail references
+				if let Some(OutputPosEntry::Head {
+					pos: current_pos,
+					next: current_next,
+				}) = Self::get_entry(batch, commit, head)?
+				{
+					let head = OutputPosEntry::Head {
+						pos: new_pos,
+						next: current_pos.pos,
+					};
+					let middle = OutputPosEntry::Middle {
+						pos: current_pos,
+						next: current_next,
+						prev: new_pos.pos,
+					};
+					let list = OutputPosList::Multi {
+						head: new_pos.pos,
+						tail,
+					};
+					batch
+						.db
+						.put_ser(&Self::entry_key(commit, new_pos.pos), &head)?;
+					batch
+						.db
+						.put_ser(&Self::entry_key(commit, current_pos.pos), &middle)?;
+					batch.db.put_ser(&Self::list_key(commit), &list)?;
+				} else {
+					return Err(Error::OtherErr("expected head to be head variant".into()));
+				}
 			}
 		}
 		Ok(())
diff --git a/chain/src/types.rs b/chain/src/types.rs
index 5dc47564cb..ffc9a614f8 100644
--- a/chain/src/types.rs
+++ b/chain/src/types.rs
@@ -283,7 +283,7 @@ impl Writeable for CommitPos {
 	}
 }
 
-#[derive(Clone, Copy, Debug)]
+#[derive(Clone, Copy, Debug, PartialEq)]
 pub struct OutputPos {
 	/// MMR position
 	pub pos: u64,
diff --git a/chain/tests/store_output_pos_list.rs b/chain/tests/store_output_pos_list.rs
new file mode 100644
index 0000000000..7c1c6cb817
--- /dev/null
+++ b/chain/tests/store_output_pos_list.rs
@@ -0,0 +1,104 @@
+// Copyright 2020 The Grin Developers
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use grin_chain as chain;
+use grin_core as core;
+use grin_util as util;
+
+use crate::chain::store::{ChainStore, OutputPosList};
+use crate::chain::types::OutputPos;
+use crate::core::core::OutputFeatures;
+use crate::util::secp::pedersen::Commitment;
+mod chain_test_helper;
+
+use self::chain_test_helper::clean_output_dir;
+
+#[test]
+fn test_store_output_pos_list() {
+	util::init_test_logger();
+
+	let chain_dir = ".grin_idx_1";
+	clean_output_dir(chain_dir);
+
+	let store = ChainStore::new(chain_dir).unwrap();
+
+	let batch = store.batch().unwrap();
+
+	let commit = Commitment::from_vec(vec![]);
+
+	assert_eq!(OutputPosList::get_list(&batch, commit), Ok(None));
+
+	assert_eq!(
+		OutputPosList::push_entry(
+			&batch,
+			commit,
+			OutputPos {
+				pos: 1,
+				height: 1,
+				features: OutputFeatures::Plain,
+			},
+		),
+		Ok(()),
+	);
+
+	assert_eq!(
+		OutputPosList::get_list(&batch, commit),
+		Ok(Some(OutputPosList::Unique {
+			pos: OutputPos {
+				pos: 1,
+				height: 1,
+				features: OutputFeatures::Plain
+			}
+		})),
+	);
+
+	assert_eq!(
+		OutputPosList::push_entry(
+			&batch,
+			commit,
+			OutputPos {
+				pos: 2,
+				height: 2,
+				features: OutputFeatures::Plain,
+			},
+		),
+		Ok(()),
+	);
+
+	assert_eq!(
+		OutputPosList::get_list(&batch, commit),
+		Ok(Some(OutputPosList::Multi { head: 2, tail: 1 })),
+	);
+
+	assert_eq!(
+		OutputPosList::push_entry(
+			&batch,
+			commit,
+			OutputPos {
+				pos: 3,
+				height: 3,
+				features: OutputFeatures::Plain,
+			},
+		),
+		Ok(()),
+	);
+
+	assert_eq!(
+		OutputPosList::get_list(&batch, commit),
+		Ok(Some(OutputPosList::Multi { head: 3, tail: 1 })),
+	);
+
+	// Cleanup chain directory
+	clean_output_dir(chain_dir);
+}
diff --git a/store/src/lmdb.rs b/store/src/lmdb.rs
index 1419fc7ae5..7dd9a62615 100644
--- a/store/src/lmdb.rs
+++ b/store/src/lmdb.rs
@@ -47,6 +47,9 @@ pub enum Error {
 	/// Wraps a serialization error for Writeable or Readable
 	#[fail(display = "Serialization Error")]
 	SerErr(String),
+	/// Other error
+	#[fail(display = "Other Error")]
+	OtherErr(String),
 }
 
 impl From<lmdb::error::Error> for Error {