Allow people to initialize a database without

Issue: #54

septentrion/core.py

@@ -73,7 +73,9 @@ def get_closest_version(
 
 # TODO: refactor this and the function below
 # TODO: also remove files.get_special_files, it's not really useful
-def get_best_schema_version(settings: configuration.Settings) -> versions.Version:
+def get_best_schema_version(
+    settings: configuration.Settings,
+) -> Optional[versions.Version]:
     """
     Get the best candidate to init the DB.
     """
@@ -88,8 +90,6 @@ def get_best_schema_version(settings: configuration.Settings) -> versions.Versio
         existing_files=schema_files,
     )
 
-    if version is None:
-        raise exceptions.SeptentrionException("Cannot find a schema to init the DB.")
     return version
 
 

septentrion/migrate.py

@@ -29,7 +29,8 @@ def migrate(
         logger.info("Migration table is empty, loading a schema")
         # schema not inited
         schema_version = core.get_best_schema_version(settings=settings)
-        init_schema(settings=settings, init_version=schema_version, stylist=stylist)
+        if schema_version is not None:
+            init_schema(settings=settings, init_version=schema_version, stylist=stylist)
 
     # play migrations
     with stylist.activate("title") as echo:

tests/unit/test_core.py

@@ -132,8 +132,7 @@ def test_get_best_schema_version_ko(mocker, known_versions):
         {"target_version": versions.Version.from_string("1.2")}
     )
 
-    with pytest.raises(exceptions.SeptentrionException):
-        core.get_best_schema_version(settings=settings)
+    assert core.get_best_schema_version(settings=settings) is None
 
 
 def test_build_migration_plan_unknown_version(known_versions):