Create single item array filter code

Author: kpaulisse

lib/octocatalog-diff/catalog-diff/filter/single_item_array.rb

@@ -7,8 +7,8 @@
 module OctocatalogDiff
   module CatalogDiff
     class Filter
-      # Filter out changes in parameters when one catalog has a parameter that's a string and
-      # the other catalog has that same parameter as an array containing the same string.
+      # Filter out changes in parameters when one catalog has a parameter that's an object and
+      # the other catalog has that same parameter as an array containing the same object.
       # For example, under this filter, the following is not a change:
       #   catalog1: notify => "Service[foo]"
       #   catalog2: notify => ["Service[foo]"]
@@ -18,9 +18,27 @@ class SingleItemArray < OctocatalogDiff::CatalogDiff::Filter
         #
         # @param diff [OctocatalogDiff::API::V1::Diff] Difference
         # @param _options [Hash] Additional options (there are none for this filter)
-        # @return [Boolean] true if this difference is a YAML file with identical objects, false otherwise
-        def filtered?(_diff, _options = {})
-          false
+        # @return [Boolean] true if this should be filtered out, false otherwise
+        def filtered?(diff, _options = {})
+          # Skip additions or removals - focus only on changes
+          return false unless diff.change?
+          old_value = diff.old_value
+          new_value = diff.new_value
+
+          # Skip unless there is a single-item array under consideration
+          return false unless
+            (old_value.is_a?(Array) && old_value.size == 1) ||
+            (new_value.is_a?(Array) && new_value.size == 1)
+
+          # Skip if both the old value and new value are arrays
+          return false if old_value.is_a?(Array) && new_value.is_a?(Array)
+
+          # Do comparison
+          if old_value.is_a?(Array)
+            old_value.first == new_value
+          else
+            new_value.first == old_value
+          end
         end
       end
     end