Catch all yaml exceptions

Instead of catching 2 specific exceptions, rather catch the generic
YAMLError as the documentation suggests:
http://pyyaml.org/wiki/PyYAMLDocumentation#YAMLError

Closes-bug: #1242155
Change-Id: I840d5eccafcc576d7a0022d81e5bc50af2d77803

heat/common/environment_format.py

@@ -29,8 +29,8 @@ def parse(env_str):
     '''
     try:
         env = yaml.load(env_str, Loader=yaml_loader)
-    except (yaml.scanner.ScannerError, yaml.parser.ParserError) as e:
-        raise ValueError(e)
+    except yaml.YAMLError as yea:
+        raise ValueError(yea)
     else:
         if env is None:
             env = {}

heat/common/template_format.py

@@ -66,8 +66,8 @@ def parse(tmpl_str):
     else:
         try:
             tpl = yaml.load(tmpl_str, Loader=yaml_loader)
-        except (yaml.scanner.ScannerError, yaml.parser.ParserError) as e:
-            raise ValueError(e)
+        except yaml.YAMLError as yea:
+            raise ValueError(yea)
         else:
             if tpl is None:
                 tpl = {}

heat/tests/test_environment_format.py

@@ -12,10 +12,17 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+import mock
+import testscenarios
+import yaml
+
 from heat.common import environment_format
 from heat.tests import common
 
 
+load_tests = testscenarios.load_tests_apply_scenarios
+
+
 class YamlEnvironmentTest(common.HeatTestCase):
 
     def test_minimal_yaml(self):
@@ -41,3 +48,22 @@ resource_regis: {}
 parameters: }
 '''
         self.assertRaises(ValueError, environment_format.parse, env)
+
+
+class YamlParseExceptions(common.HeatTestCase):
+
+    scenarios = [
+        ('scanner', dict(raised_exception=yaml.scanner.ScannerError())),
+        ('parser', dict(raised_exception=yaml.parser.ParserError())),
+        ('reader',
+         dict(raised_exception=yaml.reader.ReaderError('', '', '', '', ''))),
+    ]
+
+    def test_parse_to_value_exception(self):
+        text = 'not important'
+
+        with mock.patch.object(yaml, 'load') as yaml_loader:
+            yaml_loader.side_effect = self.raised_exception
+
+            self.assertRaises(ValueError,
+                              environment_format.parse, text)

heat/tests/test_template_format.py

@@ -12,8 +12,10 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-from testtools import skipIf
+import mock
 import os
+import testtools
+import testscenarios
 import yaml
 
 from heat.engine import clients
@@ -23,6 +25,8 @@ from heat.common import template_format
 from heat.tests.common import HeatTestCase
 from heat.tests import utils
 
+load_tests = testscenarios.load_tests_apply_scenarios
+
 
 class JsonToYamlTest(HeatTestCase):
 
@@ -105,6 +109,25 @@ Outputs: {}
         self.assertEqual(msg, str(ex))
 
 
+class YamlParseExceptions(HeatTestCase):
+
+    scenarios = [
+        ('scanner', dict(raised_exception=yaml.scanner.ScannerError())),
+        ('parser', dict(raised_exception=yaml.parser.ParserError())),
+        ('reader',
+         dict(raised_exception=yaml.reader.ReaderError('', '', '', '', ''))),
+    ]
+
+    def test_parse_to_value_exception(self):
+        text = 'not important'
+
+        with mock.patch.object(yaml, 'load') as yaml_loader:
+            yaml_loader.side_effect = self.raised_exception
+
+            self.assertRaises(ValueError,
+                              template_format.parse, text)
+
+
 class JsonYamlResolvedCompareTest(HeatTestCase):
 
     def setUp(self):
@@ -146,7 +169,8 @@ class JsonYamlResolvedCompareTest(HeatTestCase):
         for key in stack1:
             self.assertEqual(stack1[key].t, stack2[key].t)
 
-    @skipIf(clients.neutronclient is None, 'neutronclient unavailable')
+    @testtools.skipIf(clients.neutronclient is None,
+                      'neutronclient unavailable')
     def test_neutron_resolved(self):
         self.compare_stacks('Neutron.template', 'Neutron.yaml', {})