Re-write sqlite BigInteger mapping test

This test makes sure that our hook that compiles BigInteger() into
INTEGER for sqlite instead of BIGINT is working as we expect.
Unfortunately, we've seen some problems running the sqlite command to
check the schema.

This patch rewrites the test to only use sqlalchemy APIs and avoid
calling out to the sqlite command for verification.

Change-Id: Id3964d0dd5b0ddf08ab745d6878840ff06b2f0dd
Closes-bug: #1271331
(cherry picked from commit 74ade48634)

nova/tests/db/test_sqlite.py

@@ -19,24 +19,16 @@
 
 """Test cases for sqlite-specific logic"""
 
-from nova.openstack.common import processutils
 from nova import test
-from nova import utils
-import os
 from sqlalchemy import create_engine
 from sqlalchemy import Column, BigInteger, String
+import sqlalchemy.engine.reflection
 from sqlalchemy.ext.declarative import declarative_base
 
 
 class TestSqlite(test.NoDBTestCase):
     """Tests for sqlite-specific logic."""
 
-    def setUp(self):
-        super(TestSqlite, self).setUp()
-        self.db_file = "test_bigint.sqlite"
-        if os.path.exists(self.db_file):
-            os.remove(self.db_file)
-
     def test_big_int_mapping(self):
         base_class = declarative_base()
 
@@ -46,22 +38,17 @@ class TestSqlite(test.NoDBTestCase):
             id = Column(BigInteger, primary_key=True)
             name = Column(String)
 
-        get_schema_cmd = "sqlite3 %s '.schema'" % self.db_file
-        engine = create_engine("sqlite:///%s" % self.db_file)
+        engine = create_engine('sqlite://')
         base_class.metadata.create_all(engine)
-        try:
-            output, _ = utils.execute(get_schema_cmd, shell=True)
-        except processutils.ProcessExecutionError as e:
-            # NOTE(alaski): If this check becomes necessary in other tests it
-            # should be moved into setUp.
-            if 'not found' in str(e):
-                self.skipTest(str(e))
-            else:
-                raise
-        self.assertFalse('BIGINT' in output, msg="column type BIGINT "
-                         "not converted to INTEGER in schema")
 
-    def tearDown(self):
-        if os.path.exists(self.db_file):
-            os.remove(self.db_file)
-        super(TestSqlite, self).tearDown()
+        insp = sqlalchemy.engine.reflection.Inspector.from_engine(engine)
+
+        id_type = None
+        for column in insp.get_columns('users'):
+            if column['name'] == 'id':
+                id_type = column['type'].compile()
+
+        # NOTE(russellb) We have a hook in nova.db.sqlalchemy that makes it so
+        # BigInteger() is compiled to INTEGER for sqlite instead of BIGINT.
+
+        self.assertEqual('INTEGER', id_type)