Skip test if sqlite3 not installed

The test is attempting to run the sqlite3 binary during its test run.
Since there's no guarantee that it's installed it should catch an
execution error and skip.

Change-Id: I9f4ed1872fcfe3b8393644a77692dbfcce8ecab2
Closes-bug: 1227868

nova/tests/db/test_sqlite.py

@@ -19,6 +19,7 @@
 
 """Test cases for sqlite-specific logic"""
 
+from nova.openstack.common import processutils
 from nova import test
 from nova import utils
 import os
@@ -48,7 +49,15 @@ class User(base_class):
         get_schema_cmd = "sqlite3 %s '.schema'" % self.db_file
         engine = create_engine("sqlite:///%s" % self.db_file)
         base_class.metadata.create_all(engine)
-        output, _ = utils.execute(get_schema_cmd, shell=True)
+        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")