def test_removals(self):
c = SetUpdateClause('s', {1, 2}, previous={1, 2, 3})
c._analyze()
c.set_context_id(0)
self.assertIsNone(c._assignments)
self.assertIsNone(c._additions)
self.assertEqual(c._removals, {3})
self.assertEqual(c.get_context_size(), 1)
self.assertEqual(str(c), '"s" = "s" - %(0)s')
ctx = {}
c.update_context(ctx)
self.assertEqual(ctx, {'0': {3}})
def test_no_update(self):
""" tests an unchanged value creates an empty update statement """
c = SetUpdateClause('s', {1, 2}, previous={1, 2})
c._analyze()
c.set_context_id(0)
self.assertIsNone(c._assignments)
self.assertIsNone(c._additions)
self.assertIsNone(c._removals)
self.assertEqual(c.get_context_size(), 0)
self.assertEqual(str(c), '')
ctx = {}
c.update_context(ctx)
self.assertEqual(ctx, {})
def test_update_empty_set(self):
"""tests assigning a set to an empty set creates a nonempty
update statement and nonzero context size."""
c = SetUpdateClause(field='s', value=set())
c._analyze()
c.set_context_id(0)
self.assertEqual(c._assignments, set())
self.assertIsNone(c._additions)
self.assertIsNone(c._removals)
self.assertEqual(c.get_context_size(), 1)
self.assertEqual(str(c), '"s" = %(0)s')
ctx = {}
c.update_context(ctx)
self.assertEqual(ctx, {'0': set()})