moved tests directory

tests_dir/update.py

@@ -0,0 +1,16 @@
+p1=people
+p2=p1.rename({'id':'i'})
+p2=p2.rename({'i':'id'})
+assert p1==p2
+assert p1._readonly
+assert p2._readonly
+# It is VERY important to not change the original relations
+# or other tests might fail randomly, since the relations are
+# only loaded once
+
+p2.update('age==20', {'age':50})
+assert p2._readonly == False
+assert p1!=p2
+p3 = p2.selection('age!=50')
+p4 = p1.selection('age!=20')
+assert p3==p4