add tests for sqlitemanager util class

+ implement pendulum in date_string_to_time_passed()
+ remove unused bisection_search_string

app/db/sqlite/artists.py

@@ -10,7 +10,7 @@ from .utils import SQLiteManager
 
 class SQLiteArtistMethods:
     @staticmethod
-    def insert_one_artist(cur: Cursor, artisthash: str, colors: str | list[str]):
+    def insert_one_artist(cur: Cursor, artisthash: str, colors: list[str]):
         """
         Inserts a single artist into the database.
         """
@@ -23,16 +23,23 @@ class SQLiteArtistMethods:
         cur.execute(sql, (artisthash, colors))
 
     @staticmethod
-    def get_all_artists():
+    def get_all_artists(cur_: Cursor = None):
         """
         Get all artists from the database and return a generator of Artist objects
         """
         sql = """SELECT * FROM artists"""
 
-        with SQLiteManager() as cur:
-            cur.execute(sql)
+        if not cur_:
+            with SQLiteManager() as cur:
+                cur.execute(sql)
 
-            for artist in cur.fetchall():
+                for artist in cur.fetchall():
+                    yield artist
+
+                cur.close()
+
+        else:
+            cur_.execute(sql)
+
+            for artist in cur_.fetchall():
                 yield artist
-
-            cur.close()