adds the ability to clear db

kordophone-db/src/repository.rs

@@ -222,6 +222,18 @@ impl<'a> Repository<'a> {
         Ok(message_record.map(|r| r.into()))
     }
 
+    pub fn delete_all_conversations(&mut self) -> Result<()> {
+        use crate::schema::conversations::dsl::*;
+        diesel::delete(conversations).execute(self.connection)?;
+        Ok(())
+    }
+
+    pub fn delete_all_messages(&mut self) -> Result<()> {
+        use crate::schema::messages::dsl::*;
+        diesel::delete(messages).execute(self.connection)?;
+        Ok(())
+    }
+
     // Helper function to get the last inserted row ID
     // This is a workaround since the Sqlite backend doesn't support `RETURNING`
     // Huge caveat with this is that it depends on whatever the last insert was, prevents concurrent inserts.