159 lines
4.1 KiB
Ruby
159 lines
4.1 KiB
Ruby
# frozen_string_literal: true
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require 'spec_helper'
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RSpec.describe LooksAhead do
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include GraphqlHelpers
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let_it_be(:the_user) { create(:user) }
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let_it_be(:label_a) { create(:label) }
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let_it_be(:label_b) { create(:label) }
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let_it_be(:issue_a) { create(:issue, author: the_user, labels: [label_a, label_b]) }
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let_it_be(:issue_b) { create(:issue, author: the_user, labels: [label_a]) }
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let_it_be(:issue_c) { create(:issue, author: the_user, labels: [label_b]) }
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# Simplified schema to test lookahead
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let_it_be(:schema) do
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issues_resolver = Class.new(GraphQL::Schema::Resolver) do
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include LooksAhead
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def resolve_with_lookahead(**args)
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apply_lookahead(object.issues)
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end
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def preloads
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{ labels: [:labels] }
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end
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end
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label = Class.new(GraphQL::Schema::Object) do
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graphql_name 'Label'
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field :id, Integer, null: false
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end
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issue = Class.new(GraphQL::Schema::Object) do
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graphql_name 'Issue'
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field :title, String, null: true
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field :labels, label.connection_type, null: true
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end
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user = Class.new(GraphQL::Schema::Object) do
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graphql_name 'User'
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field :name, String, null: true
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field :issues, issue.connection_type, null: true
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field :issues_with_lookahead, issue.connection_type, resolver: issues_resolver, null: true
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end
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Class.new(GraphQL::Schema) do
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query(Class.new(GraphQL::Schema::Object) do
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graphql_name 'Query'
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field :find_user, user, null: true do
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argument :username, String, required: true
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end
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def find_user(username:)
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context[:user_db].find { |u| u.username == username }
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end
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end)
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end
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end
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def query(doc = document)
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GraphQL::Query.new(schema,
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document: doc,
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context: { user_db: [the_user] },
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variables: { username: the_user.username })
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end
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let(:document) do
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GraphQL.parse <<-GRAPHQL
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query($username: String!){
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findUser(username: $username) {
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name
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issues {
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nodes {
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title
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labels { nodes { id } }
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}
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}
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issuesWithLookahead {
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nodes {
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title
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labels { nodes { id } }
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}
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}
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}
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}
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GRAPHQL
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end
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def run_query(gql_query)
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query(GraphQL.parse(gql_query)).result
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end
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shared_examples 'a working query on the test schema' do
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it 'has a good test setup', :aggregate_failures do
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expected_label_ids = [label_a, label_b].cycle.take(4).map(&:id)
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issue_titles = [issue_a, issue_b, issue_c].map(&:title)
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res = query.result
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expect(res['errors']).to be_blank
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expect(res.dig('data', 'findUser', 'name')).to eq(the_user.name)
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%w[issues issuesWithLookahead].each do |field|
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expect(all_issue_titles(res, field)).to match_array(issue_titles)
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expect(all_label_ids(res, field)).to match_array(expected_label_ids)
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end
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end
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end
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it_behaves_like 'a working query on the test schema'
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it 'preloads labels on issues' do
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expect(the_user.issues).to receive(:preload).with(:labels)
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query.result
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end
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it 'issues fewer queries than the naive approach' do
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the_user.reload # ensure no attributes are loaded before we begin
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naive = <<-GQL
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query($username: String!){
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findUser(username: $username) {
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name
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issues {
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nodes {
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labels { nodes { id } }
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}
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}
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}
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}
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GQL
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with_lookahead = <<-GQL
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query($username: String!){
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findUser(username: $username) {
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name
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issuesWithLookahead {
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nodes {
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labels { nodes { id } }
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}
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}
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}
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}
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GQL
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expect { run_query(with_lookahead) }.to issue_fewer_queries_than { run_query(naive) }
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end
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private
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def all_label_ids(result, field_name)
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result.dig('data', 'findUser', field_name, 'nodes').flat_map do |node|
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node.dig('labels', 'nodes').map { |n| n['id'] }
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end
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end
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def all_issue_titles(result, field_name)
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result.dig('data', 'findUser', field_name, 'nodes').map do |node|
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node['title']
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end
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end
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end
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