db: Create a function for checking if this is a new database

So the tagdb can attempt to import tracks if none have been added to the
sql database yet.

Signed-off-by: Anna Schumaker <Anna@NoWheyCreamery.com>

db/__init__.py

@@ -2,6 +2,13 @@
 import lib
 import pathlib
 
+def new_db():
+    from . import sql
+    try:
+        return sql.execute("SELECT COUNT(*) from tracks").fetchone()[0] == 0
+    except:
+        return True
+
 
 from . import artist
 from . import album

db/test_db.py

@@ -0,0 +1,9 @@
+# Copyright 2021 (c) Anna Schumaker.
+import db
+import unittest
+
+class TestDB(unittest.TestCase):
+    def test_new_db(self):
+        self.assertTrue(db.new_db())
+        db.make_fake_track(1, 1, "Test Track", "/a/b/c/1.ogg")
+        self.assertFalse(db.new_db())