Add gitlab:graphql:analyze task

lib/gitlab/graphql/queries.rb

@@ -145,6 +145,20 @@ module Gitlab
           return redacted if printer.fields_printed > 0
         end
 
+        def complexity(schema)
+          # See BaseResolver::resolver_complexity
+          # we want to see the max possible complexity.
+          fake_args = Struct
+            .new(:if, :keyword_arguments)
+            .new(nil, { sort: true, search: true })
+
+          query = GraphQL::Query.new(schema, text)
+          # We have no arguments, so fake them.
+          query.define_singleton_method(:arguments_for) { |_x, _y| fake_args }
+
+          GraphQL::Analysis::AST.analyze_query(query, [GraphQL::Analysis::AST::QueryComplexity]).first
+        end
+
         def query
           return @query if defined?(@query)
 

lib/tasks/gitlab/graphql.rake

@@ -33,7 +33,31 @@ namespace :gitlab do
   )
 
   namespace :graphql do
-    desc 'Gitlab | GraphQL | Validate queries'
+    desc 'GitLab | GraphQL | Analyze queries'
+    task analyze: [:environment, :enable_feature_flags] do |t, args|
+      queries = if args.to_a.present?
+                  args.to_a.flat_map { |path| Gitlab::Graphql::Queries.find(path) }
+                else
+                  Gitlab::Graphql::Queries.all
+                end
+
+      queries.each do |defn|
+        $stdout.puts defn.file
+        summary, errs = defn.validate(GitlabSchema)
+
+        if summary == :client_query
+          $stdout.puts " - client query"
+        elsif errs.present?
+          $stdout.puts " - invalid query"
+        else
+          $stdout.puts " - complexity: #{defn.complexity(GitlabSchema)}"
+        end
+
+        $stdout.puts ""
+      end
+    end
+
+    desc 'GitLab | GraphQL | Validate queries'
     task validate: [:environment, :enable_feature_flags] do |t, args|
       queries = if args.to_a.present?
                   args.to_a.flat_map { |path| Gitlab::Graphql::Queries.find(path) }

spec/lib/gitlab/graphql/queries_spec.rb

@@ -151,6 +151,10 @@ RSpec.describe Gitlab::Graphql::Queries do
       let(:path) { 'post_by_slug.graphql' }
 
       it_behaves_like 'a valid GraphQL query for the blog schema'
+
+      it 'has a complexity' do
+        expect(subject.complexity(schema)).to be < 10
+      end
     end
 
     context 'a query with an import' do