Make database and library optional (#86)

Closes #25

Reviewed-on: #86

.gitea/scripts/coverage.py

@@ -1,12 +1,17 @@
 import argparse
 import json
+import sys
 
 
 def main(coverage_file, fail_under):
     with open(coverage_file, encoding="utf-8") as f:
         coverage_json = json.load(f)
     coverage = float(coverage_json["message"][:-1])
-    return coverage >= fail_under
+    print(f"Code coverage: {coverage:.2f}%; Threshold: {fail_under:.2f}%")
+    success = coverage >= fail_under
+    if coverage < fail_under:
+        print("Insufficient code coverage", file=sys.stderr)
+    return success
 
 
 if __name__ == "__main__":

src/database/mod.rs

@@ -20,6 +20,19 @@ pub trait IDatabase {
     fn save<S: Serialize + 'static>(&mut self, collection: &S) -> Result<(), SaveError>;
 }
 
+/// Non-implementation defined to make generics easier.
+pub struct NoDatabase {}
+
+impl IDatabase for NoDatabase {
+    fn load<D: DeserializeOwned + 'static>(&self, _collection: &mut D) -> Result<(), LoadError> {
+        panic!()
+    }
+
+    fn save<S: Serialize + 'static>(&mut self, _collection: &S) -> Result<(), SaveError> {
+        panic!()
+    }
+}
+
 /// Error type for database calls.
 #[derive(Debug)]
 pub enum LoadError {
@@ -76,7 +89,23 @@ impl From<std::io::Error> for SaveError {
 mod tests {
     use std::io;
 
-    use super::{LoadError, SaveError};
+    use super::{IDatabase, LoadError, NoDatabase, SaveError};
+
+    #[test]
+    #[should_panic]
+    fn no_database_load() {
+        let database = NoDatabase {};
+        let mut collection: Vec<String> = vec![];
+        _ = database.load(&mut collection);
+    }
+
+    #[test]
+    #[should_panic]
+    fn no_database_save() {
+        let mut database = NoDatabase {};
+        let collection: Vec<String> = vec![];
+        _ = database.save(&collection);
+    }
 
     #[test]
     fn errors() {

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,
-    database: DB,
+    library: Option<LIB>,
+    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,
@@ -476,30 +476,45 @@ impl<LIB: ILibrary, DB: IDatabase> MusicHoard<LIB, DB> {
     }
 
     pub fn rescan_library(&mut self) -> Result<(), Error> {
-        let items = self.library.list(&Query::new())?;
-        let mut library = Self::items_to_artists(items);
-        Self::sort(&mut library);
+        match self.library {
+            Some(ref 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);
+                let collection = mem::take(&mut self.collection);
+                self.collection = Self::merge(library_collection, collection);
 
-        Ok(())
+                Ok(())
+            }
+            None => Err(Error::LibraryError(String::from("library not provided"))),
+        }
     }
 
     pub fn load_from_database(&mut self) -> Result<(), Error> {
-        let mut database: Collection = vec![];
-        self.database.load(&mut database)?;
-        Self::sort(&mut database);
+        match self.database {
+            Some(ref 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);
+                let collection = mem::take(&mut self.collection);
+                self.collection = Self::merge(collection, database_collection);
 
-        Ok(())
+                Ok(())
+            }
+            None => Err(Error::DatabaseError(String::from("database not provided"))),
+        }
     }
 
     pub fn save_to_database(&mut self) -> Result<(), Error> {
-        self.database.save(&self.collection)?;
-        Ok(())
+        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 {
@@ -601,7 +616,10 @@ mod tests {
     use mockall::predicate;
     use once_cell::sync::Lazy;
 
-    use crate::{database::MockIDatabase, library::MockILibrary};
+    use crate::{
+        database::{MockIDatabase, NoDatabase},
+        library::{MockILibrary, NoLibrary},
+    };
 
     use super::*;
 
@@ -834,7 +852,7 @@ 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 +879,7 @@ 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 +906,7 @@ 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 +925,7 @@ 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 +954,7 @@ 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!(
@@ -946,6 +964,18 @@ mod tests {
         music_hoard.save_to_database().unwrap();
     }
 
+    #[test]
+    fn library_not_provided() {
+        let library: Option<NoLibrary> = None;
+        let database = Some(MockIDatabase::new());
+        let mut music_hoard = MusicHoard::new(library, database);
+
+        let actual_err = music_hoard.rescan_library().unwrap_err();
+        let expected_err = Error::LibraryError(String::from("library not provided"));
+
+        assert_eq!(actual_err, expected_err);
+    }
+
     #[test]
     fn library_error() {
         let mut library = MockILibrary::new();
@@ -958,7 +988,7 @@ 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 =
@@ -968,6 +998,23 @@ mod tests {
         assert_eq!(actual_err.to_string(), expected_err.to_string());
     }
 
+    #[test]
+    fn database_not_provided() {
+        let library = Some(MockILibrary::new());
+        let database: Option<NoDatabase> = None;
+        let mut music_hoard = MusicHoard::new(library, database);
+
+        let expected_err = Error::DatabaseError(String::from("database not provided"));
+
+        let actual_err = music_hoard.load_from_database().unwrap_err();
+        assert_eq!(actual_err, expected_err);
+        assert_eq!(actual_err.to_string(), expected_err.to_string());
+
+        let actual_err = music_hoard.save_to_database().unwrap_err();
+        assert_eq!(actual_err, expected_err);
+        assert_eq!(actual_err.to_string(), expected_err.to_string());
+    }
+
     #[test]
     fn database_load_error() {
         let library = MockILibrary::new();
@@ -980,7 +1027,7 @@ 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 +1050,7 @@ 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/library/mod.rs

@@ -17,6 +17,15 @@ pub trait ILibrary {
     fn list(&mut self, query: &Query) -> Result<Vec<Item>, Error>;
 }
 
+/// Non-implementation defined to make generics easier.
+pub struct NoLibrary {}
+
+impl ILibrary for NoLibrary {
+    fn list(&mut self, _query: &Query) -> Result<Vec<Item>, Error> {
+        panic!()
+    }
+}
+
 /// An item from the library. An item corresponds to an individual file (usually a single track).
 #[derive(Debug, PartialEq, Eq, Hash)]
 pub struct Item {
@@ -127,7 +136,14 @@ impl From<Utf8Error> for Error {
 mod tests {
     use std::io;
 
-    use super::{Error, Field, Query};
+    use super::{Error, Field, ILibrary, NoLibrary, Query};
+
+    #[test]
+    #[should_panic]
+    fn no_library_list() {
+        let mut library = NoLibrary {};
+        _ = library.list(&Query::default());
+    }
 
     #[test]
     fn query() {

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();