Improve extendable CI/CD config hash collection

2 files changed, 27 insertions, 16 deletions

diff --git a/lib/gitlab/ci/config/extendable/collection.rb b/lib/gitlab/ci/config/extendable/collection.rb
index e59884439a2..cdc8eb6614d 100644
--- a/lib/gitlab/ci/config/extendable/collection.rb
+++ b/lib/gitlab/ci/config/extendable/collection.rb
@@ -6,26 +6,23 @@ module Gitlab
           include Enumerable
 
           ExtensionError = Class.new(StandardError)
+          InvalidExtensionError = Class.new(ExtensionError)
           CircularDependencyError = Class.new(ExtensionError)
 
           def initialize(hash)
-            @hash = hash
+            @hash = hash.dup
+
+            each { |entry| entry.extend! if entry.extensible? }
           end
 
           def each
-            @hash.each_pair do |key, value|
-              next unless value.key?(:extends)
-
+            @hash.each_key do |key|
               yield Extendable::Entry.new(key, @hash)
             end
           end
 
-          def extend!
-            each do |entry|
-              raise ExtensionError unless entry.valid?
-
-              entry.extend!
-            end
+          def to_hash
+            @hash.to_h
           end
         end
       end
diff --git a/lib/gitlab/ci/config/extendable/entry.rb b/lib/gitlab/ci/config/extendable/entry.rb
index 96b0bd1a2ce..d5eef647b3e 100644
--- a/lib/gitlab/ci/config/extendable/entry.rb
+++ b/lib/gitlab/ci/config/extendable/entry.rb
@@ -19,9 +19,9 @@ module Gitlab
             @value ||= @context.fetch(@key)
           end
 
-          def base
+          def base_hash
             Extendable::Entry
-              .new(extends, @context, self)
+              .new(extends_key, @context, self)
               .extend!
           end
 
@@ -29,8 +29,8 @@ module Gitlab
             value.key?(:extends)
           end
 
-          def extends
-            value.fetch(:extends).to_sym
+          def extends_key
+            value.fetch(:extends).to_s.to_sym
           end
 
           def path
@@ -38,16 +38,30 @@ module Gitlab
           end
 
           def extend!
-            if path.count(key) > 1
+            if circular_dependency?
               raise Extendable::Collection::CircularDependencyError
             end
 
+            if invalid_extends_key?
+              raise Extendable::Collection::InvalidExtensionError
+            end
+
             if extensible?
-              @context[key] = base.deep_merge(value)
+              @context[key] = base_hash.deep_merge(value)
             else
               value
             end
           end
+
+          private
+
+          def circular_dependency?
+            path.count(key) > 1
+          end
+
+          def invalid_extends_key?
+            !@context.key?(key)
+          end
         end
       end
     end