Drop default-related structures after the Table is dropped.

Fixed bug where a :class:`.Sequence` would be dropped explicitly before any
:class:`.Table` that refers to it, which breaks in the case when the
sequence is also involved in a server-side default for that table, when
using :meth:`.MetaData.drop_all`.   The step which processes sequences
to be dropped via non server-side column default functions is now invoked
after the table itself is dropped.

Change-Id: I185f2cc76d2011ad4dd3ba9bde5d8aef0ec335ae
Fixes: #4300

1 files changed, 80 insertions, 0 deletions

diff --git a/test/sql/test_defaults.py b/test/sql/test_defaults.py
index 0d4eecf6a..42514a927 100644
--- a/test/sql/test_defaults.py
+++ b/test/sql/test_defaults.py
@@ -17,6 +17,7 @@ from sqlalchemy.util import u, b
 from sqlalchemy import util
 from sqlalchemy.testing import mock
 import itertools
+from sqlalchemy.testing.assertsql import CompiledSQL, AllOf, EachOf
 
 t = f = f2 = ts = currenttime = metadata = default_generator = None
 
@@ -1312,6 +1313,85 @@ class TableBoundSequenceTest(fixtures.TestBase):
              (4, "name4", 4)])
 
 
+class SequenceAsServerDefaultTest(
+        testing.AssertsExecutionResults, fixtures.TablesTest):
+    __requires__ = ('sequences_as_server_defaults',)
+    __backend__ = True
+
+    run_create_tables = 'each'
+
+    @classmethod
+    def define_tables(cls, metadata):
+        m = metadata
+
+        s = Sequence("t_seq", metadata=m)
+        Table(
+            "t_seq_test", m,
+            Column("id", Integer, s, server_default=s.next_value()),
+            Column("data", String(50))
+        )
+
+        s2 = Sequence("t_seq_2", metadata=m)
+        Table(
+            "t_seq_test_2", m,
+            Column("id", Integer, server_default=s2.next_value()),
+            Column("data", String(50))
+        )
+
+    def test_default_textual_w_default(self):
+        with testing.db.connect() as conn:
+            conn.execute("insert into t_seq_test (data) values ('some data')")
+
+            eq_(conn.scalar("select id from t_seq_test"), 1)
+
+    def test_default_core_w_default(self):
+        t_seq_test = self.tables.t_seq_test
+        with testing.db.connect() as conn:
+            conn.execute(t_seq_test.insert().values(data="some data"))
+
+            eq_(conn.scalar(select([t_seq_test.c.id])), 1)
+
+    def test_default_textual_server_only(self):
+        with testing.db.connect() as conn:
+            conn.execute(
+                "insert into t_seq_test_2 (data) values ('some data')")
+
+            eq_(conn.scalar("select id from t_seq_test_2"), 1)
+
+    def test_default_core_server_only(self):
+        t_seq_test = self.tables.t_seq_test_2
+        with testing.db.connect() as conn:
+            conn.execute(t_seq_test.insert().values(data="some data"))
+
+            eq_(conn.scalar(select([t_seq_test.c.id])), 1)
+
+    def test_drop_ordering(self):
+        self.assert_sql_execution(
+            testing.db,
+            lambda: self.metadata.drop_all(checkfirst=False),
+            AllOf(
+                CompiledSQL(
+                    "DROP TABLE t_seq_test_2",
+                    {}
+                ),
+                EachOf(
+                    CompiledSQL(
+                        "DROP TABLE t_seq_test",
+                        {}
+                    ),
+                    CompiledSQL(
+                        "DROP SEQUENCE t_seq",   # dropped as part of t_seq_test
+                        {}
+                    ),
+                ),
+            ),
+            CompiledSQL(
+                "DROP SEQUENCE t_seq_2",  # dropped as part of metadata level
+                {}
+            ),
+        )
+
+
 class SpecialTypePKTest(fixtures.TestBase):
 
     """test process_result_value in conjunction with primary key columns.