Database and library made optional

src/lib.rs

@@ -460,14 +460,14 @@ impl From<InvalidUrlError> for Error {
 /// The Music Hoard. It is responsible for pulling information from both the library and the
 /// database, ensuring its consistent and writing back any changes.
 pub struct MusicHoard<LIB, DB> {
-    library: LIB,
+    library: Option<LIB>,
-    database: DB,
+    database: Option<DB>,
     collection: Collection,
 }
 
 impl<LIB: ILibrary, DB: IDatabase> MusicHoard<LIB, DB> {
     /// Create a new [`MusicHoard`] with the provided [`ILibrary`] and [`IDatabase`].
-    pub fn new(library: LIB, database: DB) -> Self {
+    pub fn new(library: Option<LIB>, database: Option<DB>) -> Self {
         MusicHoard {
             library,
             database,
@@ -476,31 +476,46 @@ impl<LIB: ILibrary, DB: IDatabase> MusicHoard<LIB, DB> {
     }
 
     pub fn rescan_library(&mut self) -> Result<(), Error> {
-        let items = self.library.list(&Query::new())?;
+        match self.library {
-        let mut library = Self::items_to_artists(items);
+            Some(ref mut library) => {
-        Self::sort(&mut library);
+                let items = library.list(&Query::new())?;
+                let mut library_collection = Self::items_to_artists(items);
+                Self::sort(&mut library_collection);
 
                 let collection = mem::take(&mut self.collection);
-        self.collection = Self::merge(library, collection);
+                self.collection = Self::merge(library_collection, collection);
 
                 Ok(())
             }
+            None => Err(Error::LibraryError(String::from("library not provided"))),
+        }
+    }
 
     pub fn load_from_database(&mut self) -> Result<(), Error> {
-        let mut database: Collection = vec![];
+        match self.database {
-        self.database.load(&mut database)?;
+            Some(ref mut database) => {
-        Self::sort(&mut database);
+                let mut database_collection: Collection = vec![];
+                database.load(&mut database_collection)?;
+                Self::sort(&mut database_collection);
 
                 let collection = mem::take(&mut self.collection);
-        self.collection = Self::merge(collection, database);
+                self.collection = Self::merge(collection, database_collection);
 
                 Ok(())
             }
+            None => Err(Error::DatabaseError(String::from("database not provided"))),
+        }
+    }
 
     pub fn save_to_database(&mut self) -> Result<(), Error> {
-        self.database.save(&self.collection)?;
+        match self.database {
+            Some(ref mut database) => {
+                database.save(&self.collection)?;
                 Ok(())
             }
+            None => Err(Error::DatabaseError(String::from("database not provided"))),
+        }
+    }
 
     pub fn get_collection(&self) -> &Collection {
         &self.collection
@@ -834,7 +849,7 @@ mod tests {
             .times(1)
             .return_once(|_| library_result);
 
-        let mut music_hoard = MusicHoard::new(library, database);
+        let mut music_hoard = MusicHoard::new(Some(library), Some(database));
 
         music_hoard.rescan_library().unwrap();
         assert_eq!(
@@ -861,7 +876,7 @@ mod tests {
             .times(1)
             .return_once(|_| library_result);
 
-        let mut music_hoard = MusicHoard::new(library, database);
+        let mut music_hoard = MusicHoard::new(Some(library), Some(database));
 
         music_hoard.rescan_library().unwrap();
         assert_eq!(
@@ -888,7 +903,7 @@ mod tests {
             .times(1)
             .return_once(|_| library_result);
 
-        let mut music_hoard = MusicHoard::new(library, database);
+        let mut music_hoard = MusicHoard::new(Some(library), Some(database));
 
         music_hoard.rescan_library().unwrap();
         assert_eq!(music_hoard.get_collection(), &expected);
@@ -907,7 +922,7 @@ mod tests {
                 Ok(())
             });
 
-        let mut music_hoard = MusicHoard::new(library, database);
+        let mut music_hoard = MusicHoard::new(Some(library), Some(database));
 
         music_hoard.load_from_database().unwrap();
         assert_eq!(music_hoard.get_collection(), &*COLLECTION);
@@ -936,7 +951,7 @@ mod tests {
             .times(1)
             .return_once(|_: &Collection| database_result);
 
-        let mut music_hoard = MusicHoard::new(library, database);
+        let mut music_hoard = MusicHoard::new(Some(library), Some(database));
 
         music_hoard.rescan_library().unwrap();
         assert_eq!(
@@ -958,7 +973,7 @@ mod tests {
             .times(1)
             .return_once(|_| library_result);
 
-        let mut music_hoard = MusicHoard::new(library, database);
+        let mut music_hoard = MusicHoard::new(Some(library), Some(database));
 
         let actual_err = music_hoard.rescan_library().unwrap_err();
         let expected_err =
@@ -980,7 +995,7 @@ mod tests {
             .times(1)
             .return_once(|_: &mut Collection| database_result);
 
-        let mut music_hoard = MusicHoard::new(library, database);
+        let mut music_hoard = MusicHoard::new(Some(library), Some(database));
 
         let actual_err = music_hoard.load_from_database().unwrap_err();
         let expected_err = Error::DatabaseError(
@@ -1003,7 +1018,7 @@ mod tests {
             .times(1)
             .return_once(|_: &Collection| database_result);
 
-        let mut music_hoard = MusicHoard::new(library, database);
+        let mut music_hoard = MusicHoard::new(Some(library), Some(database));
 
         let actual_err = music_hoard.save_to_database().unwrap_err();
         let expected_err = Error::DatabaseError(

src/main.rs

@@ -42,7 +42,7 @@ struct Opt {
 }
 
 fn with<LIB: ILibrary, DB: IDatabase>(lib: LIB, db: DB) {
-    let music_hoard = MusicHoard::new(lib, db);
+    let music_hoard = MusicHoard::new(Some(lib), Some(db));
 
     // Initialize the terminal user interface.
     let backend = CrosstermBackend::new(io::stdout());

tests/lib.rs

@@ -30,7 +30,7 @@ fn merge_library_then_database() {
     let backend = JsonDatabaseFileBackend::new(&*database::json::DATABASE_TEST_FILE);
     let database = JsonDatabase::new(backend);
 
-    let mut music_hoard = MusicHoard::new(library, database);
+    let mut music_hoard = MusicHoard::new(Some(library), Some(database));
 
     music_hoard.rescan_library().unwrap();
     music_hoard.load_from_database().unwrap();
@@ -55,7 +55,7 @@ fn merge_database_then_library() {
     let backend = JsonDatabaseFileBackend::new(&*database::json::DATABASE_TEST_FILE);
     let database = JsonDatabase::new(backend);
 
-    let mut music_hoard = MusicHoard::new(library, database);
+    let mut music_hoard = MusicHoard::new(Some(library), Some(database));
 
     music_hoard.load_from_database().unwrap();
     music_hoard.rescan_library().unwrap();