env: rm DB_ENGINE default value

Author: SomberNight

src/electrumx/server/env.py

@@ -224,8 +224,6 @@ def db_engine_enum(self) -> str:
         choices = list_db_engine_choices()
         db_eng = self.default('DB_ENGINE', None)
 
-        if db_eng is None and electrumx.__version__.startswith("1."):  # temporary legacy hack
-            db_eng = "leveldb"
         if db_eng is None:
             raise self.Error(
                 f"required envvar DB_ENGINE not set.\n"

tests/server/test_env.py

@@ -16,6 +16,7 @@
 
 base_environ = {
     'DB_DIRECTORY': BASE_DB_DIR,
+    'DB_ENGINE': 'rocksdb',
     'DAEMON_URL': BASE_DAEMON_URL,
     'COIN': 'BitcoinSV',
 }
@@ -307,15 +308,17 @@ def test_DONATION_ADDRESS():
 
 
 def test_DB_ENGINE():
+    assert_required('DB_ENGINE')
     setup_base_env()
 
-    e = Env()
-    assert e.db_engine == "leveldb"
-
     os.environ['DB_ENGINE'] = "rocksdb"
     e = Env()
     assert e.db_engine == "rocksdb"
 
+    os.environ['DB_ENGINE'] = "leveldb"
+    e = Env()
+    assert e.db_engine == "leveldb"
+
     os.environ['DB_ENGINE'] = "custom-something"
     with pytest.raises(Env.Error):
         e = Env()