unittest load save storage

src/main.rs

@@ -1,5 +1,5 @@
 use serde::{Serialize, Deserialize};
-use std::io::Read;
+use std::io::{Read, Write};
 use std::fs::File;
 
 fn main() {
@@ -18,6 +18,21 @@ struct Add {
    tag: String,
 }
 
+fn save_storage(path: String, storage: Storage) -> Result<(), String> {
+   match File::create(path.clone()) {
+      Ok(mut writer) => _save_storage(&mut writer, storage),
+      Err(reason) => Err(format!("failed to open {} to save storage: {}", path, reason)),
+   }
+}
+
+fn _save_storage(writer: &mut dyn Write, storage: Storage) -> Result<(), String> {
+   let mut w = serde_yaml::Serializer::new(writer);
+   match storage.serialize(&mut w) {
+      Ok(_) => Ok(()),
+      Err(reason) => Err(format!("failed to serialize storage: {}", reason)),
+   }
+}
+
 fn load_storage(path: String) -> Result<Storage, String> {
    match File::open(path.clone()) {
       Ok(mut reader) => _load_storage(&mut reader),
@@ -37,19 +52,28 @@ mod tests {
    use super::*;
 
    #[test]
-   fn test_load_storage() {
+   fn test_save_load_empty() {
       let got = _load_storage(&mut "adds: []".as_bytes()).expect("failed to parse 'adds: []' storage");
       assert_eq!(got, Storage{adds: vec![]});
+
+      let mut w = vec![];
+      _save_storage(&mut w, got).expect("failed saving storage to writer");
+      assert_eq!(String::from_utf8(w).unwrap(), "adds: []\n".to_string());
    }
 
    #[test]
    fn test_testdata_standalone_yaml() {
+      let want = Storage{adds: vec![
+         Add{t: 1, add: "def".to_string(), tag: "abc".to_string()},
+         Add{t: 2, add: "ghi".to_string(), tag: "".to_string()},
+      ]};
       assert_eq!(
          load_storage("./src/testdata/standalone.yaml".to_string()).expect("cant load standalone.yaml"),
-         Storage{adds: vec![
-            Add{t: 1, add: "def".to_string(), tag: "abc".to_string()},
-            Add{t: 2, add: "ghi".to_string(), tag: "".to_string()},
-         ]},
+         want,
       );
+
+      let mut w = vec![];
+      _save_storage(&mut w, want).expect("failed saving storage to writer");
+      assert_eq!(String::from_utf8(w).unwrap(), "adds:\n- t: 1\n  add: def\n  tag: abc\n- t: 2\n  add: ghi\n  tag: ''\n".to_string());
    }
 }