1 files changed, 31 insertions, 0 deletions
diff --git a/app/graphql/types/concerns/gitlab_style_deprecations.rb b/app/graphql/types/concerns/gitlab_style_deprecations.rb
new file mode 100644
index 00000000000..2c932f4214b
--- /dev/null
+++ b/app/graphql/types/concerns/gitlab_style_deprecations.rb
@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+# Concern for handling deprecation arguments.
+# https://docs.gitlab.com/ee/development/api_graphql_styleguide.html#deprecating-fields-and-enum-values
+module GitlabStyleDeprecations
+  extend ActiveSupport::Concern
+
+  private
+
+  def gitlab_deprecation(kwargs)
+    if kwargs[:deprecation_reason].present?
+      raise ArgumentError, 'Use `deprecated` property instead of `deprecation_reason`. ' \
+                           'See https://docs.gitlab.com/ee/development/api_graphql_styleguide.html#deprecating-fields-and-enum-values'
+    end
+
+    deprecation = kwargs.delete(:deprecated)
+    return kwargs unless deprecation
+
+    milestone, reason = deprecation.values_at(:milestone, :reason).map(&:presence)
+
+    raise ArgumentError, 'Please provide a `milestone` within `deprecated`' unless milestone
+    raise ArgumentError, 'Please provide a `reason` within `deprecated`' unless reason
+    raise ArgumentError, '`milestone` must be a `String`' unless milestone.is_a?(String)
+
+    deprecated_in = "Deprecated in #{milestone}"
+    kwargs[:deprecation_reason] = "#{reason}. #{deprecated_in}"
+    kwargs[:description] += ". #{deprecated_in}: #{reason}" if kwargs[:description]
+
+    kwargs
+  end
+end