Validate null Condition section (#3169)

Author: kddejong

Diff for: src/cfnlint/rules/conditions/Configuration.py

@@ -26,8 +26,10 @@ class Configuration(CloudFormationLintRule):
     def match(self, cfn):
         matches = []
 
-        conditions = cfn.template.get("Conditions", {})
-        if conditions:
+        if "Conditions" not in cfn.template:
+            return matches
+        conditions = cfn.template.get("Conditions", None)
+        if isinstance(conditions, dict):
             for condname, condobj in conditions.items():
                 if not isinstance(condobj, dict):
                     message = "Condition {0} has invalid property"
@@ -52,5 +54,12 @@ def match(self, cfn):
                                         message.format(condname, k),
                                     )
                                 )
+        else:
+            matches.append(
+                RuleMatch(
+                    ["Conditions"],
+                    "Condition must be an object",
+                )
+            )
 
         return matches

Diff for: test/fixtures/templates/bad/conditions_type.yaml

@@ -0,0 +1,8 @@
+AWSTemplateFormatVersion: "2010-09-09"
+Conditions:
+Resources:
+    myTopic:
+      Type: AWS::SNS::Topic
+      Properties:
+        DisplayName: mytopic
+        TopicName: mytopic

Diff for: test/unit/rules/conditions/test_configuration.py

@@ -22,6 +22,10 @@ def test_file_positive(self):
         """Test Positive"""
         self.helper_file_positive()
 
+    def test_file_negative_type(self):
+        """Test failure"""
+        self.helper_file_negative("test/fixtures/templates/bad/conditions_type.yaml", 1)
+
     def test_file_negative(self):
         """Test failure"""
         self.helper_file_negative("test/fixtures/templates/bad/conditions.yaml", 4)