Improve StackValidationFailed exception

This patch adds to StackValidationFailed new
parameters 'error' for specified error like
'Property error' and 'path' for path in template
where validation failed. StackValidationFailed
message format is 'error : path: message', where
path can looks like
'resource_name.section_name.section_item_name'.

Change-Id: I3673b3220fb613c6ec28318f65ed4adcacf6ec7c

heat/common/exception.py

@@ -269,7 +269,41 @@ class StackExists(HeatException):
 
 
 class StackValidationFailed(HeatException):
-    msg_fmt = _("%(message)s")
+    msg_fmt = _("%(error)s%(path)s%(message)s")
+
+    def __init__(self, error=None, path=None, message=None):
+        self.error = error or ''
+        self.path = []
+        if path is not None:
+            if isinstance(path, list):
+                self.path = path
+            elif isinstance(path, six.string_types):
+                self.path = [path]
+
+        result_path = ''
+        for path_item in self.path:
+            if isinstance(path_item, int) or path_item.isdigit():
+                result_path += '[%s]' % path_item
+            elif len(result_path) > 0:
+                result_path += '.%s' % path_item
+            else:
+                result_path = path_item
+
+        self.error_message = message or ''
+        super(StackValidationFailed, self).__init__(
+            error=('%s : ' % self.error if self.error != '' else ''),
+            path=('%s: ' % result_path if len(result_path) > 0 else ''),
+            message=self.error_message
+        )
+
+    def error(self):
+        return self.error
+
+    def path(self):
+        return self.path
+
+    def error_message(self):
+        return self.error_message
 
 
 class InvalidSchemaError(HeatException):

heat/tests/test_exception.py

@@ -39,3 +39,91 @@ class TestHeatException(common.HeatTestCase):
         message = "This format %(message)s should work"
         err = exception.Error(message)
         self.assertEqual(message, six.text_type(err))
+
+
+class TestStackValidationFailed(common.HeatTestCase):
+
+    scenarios = [
+        ('test_full_exception', dict(
+            kwargs=dict(
+                error='Error',
+                path=['some', 'path'],
+                message='Some message'),
+            expected='Error : some.path: Some message',
+            called_error='Error',
+            called_path=['some', 'path'],
+            called_msg='Some message'
+        )),
+        ('test_no_error_exception', dict(
+            kwargs=dict(
+                path=['some', 'path'],
+                message='Chain letter'),
+            expected='some.path: Chain letter',
+            called_error='',
+            called_path=['some', 'path'],
+            called_msg='Chain letter'
+        )),
+        ('test_no_path_exception', dict(
+            kwargs=dict(
+                error='Error',
+                message='Just no.'),
+            expected='Error : Just no.',
+            called_error='Error',
+            called_path=[],
+            called_msg='Just no.'
+        )),
+        ('test_no_msg_exception', dict(
+            kwargs=dict(
+                error='Error',
+                path=['we', 'lost', 'our', 'message']),
+            expected='Error : we.lost.our.message: ',
+            called_error='Error',
+            called_path=['we', 'lost', 'our', 'message'],
+            called_msg=''
+        )),
+        ('test_old_format_exception', dict(
+            kwargs=dict(
+                message='Wow. I think I am old error message format.'
+            ),
+            expected='Wow. I think I am old error message format.',
+            called_error='',
+            called_path=[],
+            called_msg='Wow. I think I am old error message format.'
+        )),
+        ('test_int_path_item_exception', dict(
+            kwargs=dict(
+                path=['null', 0]
+            ),
+            expected='null[0]: ',
+            called_error='',
+            called_path=['null', 0],
+            called_msg=''
+        )),
+        ('test_digit_path_item_exception', dict(
+            kwargs=dict(
+                path=['null', '0']
+            ),
+            expected='null[0]: ',
+            called_error='',
+            called_path=['null', '0'],
+            called_msg=''
+        )),
+        ('test_string_path_exception', dict(
+            kwargs=dict(
+                path='null[0].not_null'
+            ),
+            expected='null[0].not_null: ',
+            called_error='',
+            called_path=['null[0].not_null'],
+            called_msg=''
+        ))
+    ]
+
+    def test_exception(self):
+        try:
+            raise exception.StackValidationFailed(**self.kwargs)
+        except exception.StackValidationFailed as ex:
+            self.assertEqual(self.expected, six.text_type(ex))
+            self.assertEqual(self.called_error, ex.error)
+            self.assertEqual(self.called_path, ex.path)
+            self.assertEqual(self.called_msg, ex.error_message)