class GraphQL::StaticValidation::FieldsWillMerge

def validate(context)
  fragments = {}
  has_selections = []
  visitor = context.visitor
  visitor[GraphQL::Language::Nodes::OperationDefinition] << -> (node, parent) {
    if node.selections.any?
      has_selections << node
    end
  }
  visitor[GraphQL::Language::Nodes::Document].leave << -> (node, parent) {
    has_selections.each { |node|
      field_map = gather_fields_by_name(node.selections, {}, [], context)
      find_conflicts(field_map, context)
    }
  }
end