Annotate resolvers as needing at least one argument

This adds a new annotation to our resolvers `requires_argument!`, which
is can be used to statically analyse fields generated from these
resolvers to determine if we can pass an empty argument set to them.

app/graphql/resolvers/base_resolver.rb

@@ -8,6 +8,14 @@ module Resolvers
 
     argument_class ::Types::BaseArgument
 
+    def self.requires_argument!
+      @requires_argument = true
+    end
+
+    def self.field_options
+      super.merge(requires_argument: @requires_argument)
+    end
+
     def self.singular_type
       return unless type
 

app/graphql/resolvers/design_management/design_resolver.rb

@@ -5,6 +5,8 @@ module Resolvers
     class DesignResolver < BaseResolver
       type ::Types::DesignManagement::DesignType, null: true
 
+      requires_argument!
+
       argument :id, ::Types::GlobalIDType[::DesignManagement::Design],
                required: false,
                description: 'Find a design by its ID'

app/graphql/resolvers/design_management/version/design_at_version_resolver.rb

@@ -12,6 +12,8 @@ module Resolvers
 
         type Types::DesignManagement::DesignAtVersionType, null: true
 
+        requires_argument!
+
         authorize :read_design
 
         argument :id, DesignAtVersionID,

app/graphql/resolvers/design_management/version_in_collection_resolver.rb

@@ -7,6 +7,8 @@ module Resolvers
 
       type Types::DesignManagement::VersionType, null: true
 
+      requires_argument!
+
       authorize :read_design
 
       alias_method :collection, :object

app/graphql/types/base_field.rb

@@ -12,6 +12,7 @@ module Types
     def initialize(*args, **kwargs, &block)
       @calls_gitaly = !!kwargs.delete(:calls_gitaly)
       @constant_complexity = !!kwargs[:complexity]
+      @requires_argument = !!kwargs.delete(:requires_argument)
       kwargs[:complexity] = field_complexity(kwargs[:resolver_class], kwargs[:complexity])
       @feature_flag = kwargs[:feature_flag]
       kwargs = check_feature_flag(kwargs)
@@ -20,6 +21,10 @@ module Types
       super(*args, **kwargs, &block)
     end
 
+    def requires_argument?
+      @requires_argument || arguments.values.any? { |argument| argument.type.non_null? }
+    end
+
     # Based on https://github.com/rmosolgo/graphql-ruby/blob/v1.11.4/lib/graphql/schema/field.rb#L538-L563
     # Modified to fix https://github.com/rmosolgo/graphql-ruby/issues/3113
     def resolve_field(obj, args, ctx)

app/graphql/types/base_interface.rb

@@ -3,5 +3,7 @@
 module Types
   module BaseInterface
     include GraphQL::Schema::Interface
+
+    field_class ::Types::BaseField
   end
 end

app/graphql/types/design_management/design_collection_type.rb

@@ -2,7 +2,7 @@
 
 module Types
   module DesignManagement
-    class DesignCollectionType < BaseObject
+    class DesignCollectionType < ::Types::BaseObject
       graphql_name 'DesignCollection'
       description 'A collection of designs'
 

spec/graphql/resolvers/concerns/looks_ahead_spec.rb

@@ -14,7 +14,7 @@ RSpec.describe LooksAhead do
 
   # Simplified schema to test lookahead
   let_it_be(:schema) do
-    issues_resolver = Class.new(Resolvers::BaseResolver) do
+    issues_resolver = Class.new(GraphQL::Schema::Resolver) do
       include LooksAhead
 
       def resolve_with_lookahead(**args)
@@ -41,7 +41,6 @@ RSpec.describe LooksAhead do
       field :issues, issue.connection_type,
         null: true
       field :issues_with_lookahead, issue.connection_type,
-        extras: [:lookahead],
         resolver: issues_resolver,
         null: true
     end

spec/support/helpers/graphql_helpers.rb

@@ -403,8 +403,18 @@ module GraphqlHelpers
     field_type(field).kind.enum?
   end
 
+  # There are a few non BaseField fields in our schema (pageInfo for one).
+  # None of them require arguments.
   def required_arguments?(field)
-    field.arguments.values.any? { |argument| argument.type.non_null? }
+    return field.requires_argument? if field.is_a?(::Types::BaseField)
+
+    if (meta = field.try(:metadata)) && meta[:type_class]
+      required_arguments?(meta[:type_class])
+    elsif args = field.try(:arguments)
+      args.values.any? { |argument| argument.type.non_null? }
+    else
+      false
+    end
   end
 
   def io_value?(value)