From 0da1c6ec7bef686f2d271e899fe7926479b9751d Mon Sep 17 00:00:00 2001
From: Dan Helfman <witten@torsion.org>
Date: Sun, 6 Sep 2015 15:55:14 -0700
Subject: [PATCH] Better error message when configuration file is missing.

---
 NEWS                                 |  1 +
 atticmatic/config.py                 |  3 ++-
 atticmatic/tests/unit/test_config.py | 10 +++++++++-
 3 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/NEWS b/NEWS
index 2a7c7aee..1b46c71f 100644
--- a/NEWS
+++ b/NEWS
@@ -1,6 +1,7 @@
 0.1.7-dev
 
  * #11: Fixed parsing of punctuation in configuration file.
+ * Better error message when configuration file is missing.
 
 0.1.6
 
diff --git a/atticmatic/config.py b/atticmatic/config.py
index 4f45b89b..ddf574d7 100644
--- a/atticmatic/config.py
+++ b/atticmatic/config.py
@@ -109,7 +109,8 @@ def parse_configuration(config_filename, config_format):
     Raise IOError if the file cannot be read, or ValueError if the format is not as expected.
     '''
     parser = RawConfigParser()
-    parser.read(config_filename)
+    if not parser.read(config_filename):
+        raise ValueError('Configuration file cannot be opened: {}'.format(config_filename))
 
     validate_configuration_format(parser, config_format)
 
diff --git a/atticmatic/tests/unit/test_config.py b/atticmatic/tests/unit/test_config.py
index 7a1866e8..4b4d3a7c 100644
--- a/atticmatic/tests/unit/test_config.py
+++ b/atticmatic/tests/unit/test_config.py
@@ -197,7 +197,7 @@ def test_parse_section_options_for_missing_section_should_return_empty_dict():
 
 def insert_mock_parser():
     parser = flexmock()
-    parser.should_receive('read')
+    parser.should_receive('read').and_return([flexmock()])
     module.RawConfigParser = lambda: parser
 
     return parser
@@ -220,3 +220,11 @@ def test_parse_configuration_should_return_section_configs():
     parsed_config = module.parse_configuration('filename', config_format)
 
     assert parsed_config == type(parsed_config)(*mock_section_configs)
+
+
+def test_parse_configuration_with_file_open_error_should_raise():
+    parser = insert_mock_parser()
+    parser.should_receive('read').and_return([])
+
+    with assert_raises(ValueError):
+        module.parse_configuration('filename', config_format=flexmock())