From 85e9411d3def955f34497cffcb2ab2c74915200f Mon Sep 17 00:00:00 2001
From: Sergey Kraynev <skraynev@mirantis.com>
Date: Tue, 25 Mar 2014 02:12:07 -0400
Subject: [PATCH] Initial validation of functions

All template functions contain only 'result' function for resolving
snippet of template. Current patch presents initial implementation of
validate method and support function 'validate' similar to 'resolve'.

Related-Bug: #1273490
Change-Id: Id81493bd72e75da746101c4c741eaf846abd8360
---
 heat/engine/function.py     | 21 ++++++++++++++++++
 heat/tests/test_function.py | 43 +++++++++++++++++++++++++++++++++++++
 2 files changed, 64 insertions(+)

diff --git a/heat/engine/function.py b/heat/engine/function.py
index 2f48ff2e82..f5a091ab83 100644
--- a/heat/engine/function.py
+++ b/heat/engine/function.py
@@ -36,6 +36,15 @@ class Function(object):
         self.fn_name = fn_name
         self.args = args
 
+    def validate(self):
+        """
+        Validate arguments without resolving the function.
+
+        Function subclasses must override this method to validate their
+        args.
+        """
+        validate(self.args)
+
     @abc.abstractmethod
     def result(self):
         """
@@ -110,3 +119,15 @@ def resolve(snippet):
         return [resolve(v) for v in snippet]
 
     return snippet
+
+
+def validate(snippet):
+    if isinstance(snippet, Function):
+        snippet.validate()
+    elif isinstance(snippet, collections.Mapping):
+        for v in snippet.values():
+            validate(v)
+    elif (not isinstance(snippet, basestring) and
+          isinstance(snippet, collections.Iterable)):
+        for v in snippet:
+            validate(v)
diff --git a/heat/tests/test_function.py b/heat/tests/test_function.py
index e0d2241b3c..885846dce3 100644
--- a/heat/tests/test_function.py
+++ b/heat/tests/test_function.py
@@ -19,6 +19,10 @@ from heat.engine import function
 
 
 class TestFunction(function.Function):
+    def validate(self):
+        if len(self.args) < 2:
+            raise Exception(_('Need more arguments'))
+
     def result(self):
         return 'wibble'
 
@@ -80,3 +84,42 @@ class ResolveTest(HeatTestCase):
         self.assertEqual(['foo', {'bar': ['baz', {'blarg': 'wibble'}]}],
                          result)
         self.assertIsNot(result, snippet)
+
+
+class ValidateTest(HeatTestCase):
+    def setUp(self):
+        super(ValidateTest, self).setUp()
+        self.func = TestFunction(None, 'foo', ['bar', 'baz'])
+
+    def test_validate_func(self):
+        self.assertIsNone(function.validate(self.func))
+        self.func = TestFunction(None, 'foo', ['bar'])
+        ex = self.assertRaises(Exception, function.validate, self.func)
+        self.assertEqual('Need more arguments', str(ex))
+
+    def test_validate_dict(self):
+        snippet = {'foo': 'bar', 'blarg': self.func}
+        function.validate(snippet)
+
+        self.func = TestFunction(None, 'foo', ['bar'])
+        snippet = {'foo': 'bar', 'blarg': self.func}
+        ex = self.assertRaises(Exception, function.validate, snippet)
+        self.assertEqual('Need more arguments', str(ex))
+
+    def test_validate_list(self):
+        snippet = ['foo', 'bar', 'baz', 'blarg', self.func]
+        function.validate(snippet)
+
+        self.func = TestFunction(None, 'foo', ['bar'])
+        snippet = {'foo': 'bar', 'blarg': self.func}
+        ex = self.assertRaises(Exception, function.validate, snippet)
+        self.assertEqual('Need more arguments', str(ex))
+
+    def test_validate_all(self):
+        snippet = ['foo', {'bar': ['baz', {'blarg': self.func}]}]
+        function.validate(snippet)
+
+        self.func = TestFunction(None, 'foo', ['bar'])
+        snippet = {'foo': 'bar', 'blarg': self.func}
+        ex = self.assertRaises(Exception, function.validate, snippet)
+        self.assertEqual('Need more arguments', str(ex))