Ignore dependency errors with conditions

If a resource is conditionally defined, depending on it raises an error
in the case it's not defined. This patch fixes that by checking if the
resource is present in the template regardless of the conditions.

Change-Id: Iefae1fcea720bee4ed69ad1a5fe403d52d54433c
Closes-Bug: #1649900

heat/engine/rsrc_defn.py

@@ -207,6 +207,10 @@ class ResourceDefinition(object):
 
         def get_resource(res_name):
             if res_name not in stack:
+                if res_name in stack.t.get(stack.t.RESOURCES):
+                    # The resource is conditionally defined, allow dependencies
+                    # on it
+                    return
                 raise exception.InvalidTemplateReference(resource=res_name,
                                                          key=self.name)
             return stack[res_name]
@@ -230,8 +234,9 @@ class ResourceDefinition(object):
                 )
             return itertools.chain()
 
-        return itertools.chain((get_resource(dep) for dep in explicit_depends),
-                               prop_deps, metadata_deps)
+        return itertools.chain(
+            filter(None, (get_resource(dep) for dep in explicit_depends)),
+            prop_deps, metadata_deps)
 
     def properties(self, schema, context=None):
         """Return a Properties object representing the resource properties.

heat/tests/test_hot.py

@@ -1806,6 +1806,25 @@ conditions:
         stack = parser.Stack(utils.dummy_context(), 'test_stack', tmpl)
         self.assertRaises(TypeError, self.resolve, snippet, tmpl, stack=stack)
 
+    def test_depends_condition(self):
+        hot_tpl = template_format.parse('''
+        heat_template_version: 2016-10-14
+        resources:
+          one:
+            type: OS::Heat::None
+          two:
+            type: OS::Heat::None
+            condition: False
+          three:
+            type: OS::Heat::None
+            depends_on: two
+        ''')
+
+        tmpl = template.Template(hot_tpl)
+        stack = parser.Stack(utils.dummy_context(), 'test_stack', tmpl)
+        stack.validate()
+        self.assertEqual({'one', 'three'}, set(stack.resources))
+
 
 class HotStackTest(common.HeatTestCase):
     """Test stack function when stack was created from HOT template."""

heat/tests/test_rsrc_defn.py

@@ -34,6 +34,16 @@ resources:
     type: OS::Heat::TestResource
 '''
 
+TEMPLATE_WITH_INVALID_EXPLICIT_DEPEND = '''
+heat_template_version: 2016-10-14
+resources:
+  test1:
+    type: OS::Heat::TestResource
+  test3:
+    type: OS::Heat::TestResource
+    depends_on: test2
+'''
+
 
 class ResourceDefinitionTest(common.HeatTestCase):
 
@@ -104,8 +114,9 @@ class ResourceDefinitionTest(common.HeatTestCase):
         self.assertEqual([], list(rsrc.t.dependencies(stack)))
 
     def test_dependencies_explicit_invalid(self):
-        rd = rsrc_defn.ResourceDefinition('rsrc', 'SomeType', depends=['baz'])
-        stack = {'foo': 'FOO', 'bar': 'BAR'}
+        t = template_format.parse(TEMPLATE_WITH_INVALID_EXPLICIT_DEPEND)
+        stack = utils.parse_stack(t)
+        rd = stack.t.resource_definitions(stack)['test3']
         self.assertRaises(exception.InvalidTemplateReference,
                           lambda: list(rd.dependencies(stack)))