add basic re-load test

src/index/io.rs

@@ -86,7 +86,8 @@ impl Index {
             .read_to_string()
             .context(format!("reading index file contents from {}", index_file_path.as_str()))?;
 
-        let index: Index = serde_json::from_str(&index_text).context(format!("cannot read index from: {}", index_text))?;
+        let index: Index =
+            serde_json::from_str(&index_text).context(format!("cannot read index from: {}", index_file_path.as_str()))?;
         Ok(index)
     }
 
@@ -115,6 +116,7 @@ impl Index {
 mod must {
     use crate::index::Index;
     use anyhow::Result;
+
     use vfs::{MemoryFS, VfsPath};
 
     #[test]
@@ -131,4 +133,17 @@ mod must {
 
         Ok(())
     }
+
+    #[test]
+    fn be_same_when_loaded_from_disk() -> Result<()> {
+        let repository_path: VfsPath = MemoryFS::new().into();
+        let mut original = Index::new()?;
+
+        original.save(&repository_path)?;
+        let loaded = Index::load(&repository_path)?;
+
+        assert_eq!(original, loaded);
+
+        Ok(())
+    }
 }

src/index/mod.rs

@@ -13,7 +13,7 @@ mod io;
 pub mod item;
 mod lock;
 
-#[derive(Serialize, Deserialize, Debug)]
+#[derive(Serialize, Deserialize, Debug, PartialEq)]
 pub struct Index {
     newest_items_by_source_path: HashMap<String, IndexItem>,
     items_by_file_id: HashMap<ItemId, IndexItem>,