If Schema_upgrader encounters a database without a schema_version set, assumes that it's a 1.5.4 schema.

controller/Schema_upgrader.py

@@ -48,8 +48,10 @@ class Schema_upgrader:
 
     try:
       from_version = self.__database.select_one( tuple, "select * from schema_version;" );
+    # if there's no schema version table, assume the from_version is 1.5.4, which was the last
+    # version not to include a schema_version table
     except:
-      from_version = None
+      from_version = ( 1, 5, 4 )
 
     if self.__database.backend == Persistent.SQLITE_BACKEND:
       extension = u"sqlite"
@@ -69,7 +71,7 @@ class Schema_upgrader:
         continue
 
       # skip those versions that won't help us upgrade
-      if from_version and version <= from_version:
+      if version <= from_version:
         continue
       if version > to_version:
         continue

controller/test/Test_schema_upgrader.py

@@ -102,6 +102,23 @@ class Test_schema_upgrader( object ):
 
     self.test_upgrade_schema();
 
+  def test_upgrade_schema_default_to_start_version_of_1_5_4( self ):
+    # test that if no schema_version table exists, then the starting version is assumed to be 1.5.4
+    self.fake_files = {
+      u"model/delta/1.5.3.sqlite": u"invalid sql;",
+      u"model/delta/1.5.4.sqlite": u"should not be invoked;",
+      u"model/delta/1.5.5.sqlite": u"create table new_table ( foo text ); insert into new_table values ( 'hi' );",
+      u"model/delta/1.5.6.sqlite": u"insert into new_table values ( 'bye' );",
+    }
+
+    self.upgrader.upgrade_schema( u"1.5.6" );
+
+    result = self.database.select_many( tuple, u"select * from new_table;" );
+    assert result == [ ( u"hi", ), ( u"bye", ), ];
+
+    result = self.database.select_many( tuple, u"select * from schema_version;" );
+    assert result == [ ( 1, 5, 6 ) ];
+
   def test_apply_schema_delta( self ):
     self.fake_files = {
       u"model/delta/5.6.5.sqlite": u"insert into new_table values ( 'should not show up' );",