deal with read_config() for empty YAML file properly (#3619)

Author: Vladimir Kotal

tools/src/main/python/opengrok_tools/utils/readconfig.py

@@ -62,6 +62,9 @@ def read_config(logger, inputfile):
                 # Not a valid YAML file.
                 logger.debug("got exception {}".format(sys.exc_info()[0]))
             else:
+                if cfg is None:
+                    cfg = {}
+
                 return cfg
     except IOError as e:
         logger.error("cannot open '{}': {}".format(inputfile, e.strerror))

tools/src/test/python/test_readconfig.py

@@ -0,0 +1,41 @@
+#!/usr/bin/env python3
+
+#
+# CDDL HEADER START
+#
+# The contents of this file are subject to the terms of the
+# Common Development and Distribution License (the "License").
+# You may not use this file except in compliance with the License.
+#
+# See LICENSE.txt included in this distribution for the specific
+# language governing permissions and limitations under the License.
+#
+# When distributing Covered Code, include this CDDL HEADER in each
+# file and include the License file at LICENSE.txt.
+# If applicable, add the following below this CDDL HEADER, with the
+# fields enclosed by brackets "[]" replaced with your own identifying
+# information: Portions Copyright [yyyy] [name of copyright owner]
+#
+# CDDL HEADER END
+#
+
+#
+# Copyright (c) 2021, Oracle and/or its affiliates. All rights reserved.
+#
+import os
+import tempfile
+from mockito import mock
+import logging
+
+from opengrok_tools.utils.readconfig import read_config
+
+
+def test_read_config_empty_yaml():
+    tmpf = tempfile.NamedTemporaryFile(mode='w+t', delete=False)
+    tmpf.file.write('#foo\n')
+    tmpf.close()
+    res = read_config(mock(spec=logging.Logger), tmpf.name)
+    os.remove(tmpf.name)
+    assert res is not None
+    assert type(res) == dict
+    assert len(res) == 0