Remaining changes from making database a required option

* Update example.conf
* Write missing test

Change-Id: I1716697f2d04947143445ac6badf61453d0d6b17

example.conf

@@ -53,8 +53,8 @@
 
 ;; General service settings
 
-; SQLite3 database to store nodes under discovery, defaults to a temporary
-; file. Do not use :memory: here, it won't work.
+; SQLite3 database to store nodes under discovery, required.
+; Do not use :memory: here, it won't work.
 ;database =
 ; Comma-separated list of enabled hooks for processing pipeline.
 ; Hook 'scheduler' updates the node with the minimum properties required by the

ironic_discoverd/node_cache.py

@@ -68,7 +68,7 @@ def init():
     global _DB_NAME
 
     _DB_NAME = conf.get('discoverd', 'database').strip()
-    if not _DB_NAME:  # pragma: no cover
+    if not _DB_NAME:
         LOG.critical('Configuration option discoverd.database should be set')
         sys.exit(1)
 

ironic_discoverd/test/test_node_cache.py

@@ -11,7 +11,9 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import tempfile
 import time
+import unittest
 
 import mock
 
@@ -179,3 +181,23 @@ class TestNodeInfoFinished(test_base.NodeTest):
             'select finished_at, error from nodes').fetchone())
         self.assertEqual([], self.db.execute(
             "select * from attributes").fetchall())
+
+
+class TestInit(unittest.TestCase):
+    def setUp(self):
+        super(TestInit, self).setUp()
+        conf.init_conf()
+        conf.CONF.add_section('discoverd')
+        node_cache._DB_NAME = None
+
+    def test_ok(self):
+        with tempfile.NamedTemporaryFile() as db_file:
+            conf.CONF.set('discoverd', 'database', db_file.name)
+            node_cache.init()
+
+            self.assertIsNotNone(node_cache._DB_NAME)
+            # Verify that table exists
+            node_cache._db().execute("select * from nodes")
+
+    def test_no_database(self):
+        self.assertRaises(SystemExit, node_cache.init)