Declare api way relations as nested resources

test/controllers/api/ways/relations_controller_test.rb

@@ -0,0 +1,69 @@
+require "test_helper"
+
+module Api
+  module Ways
+    class RelationsControllerTest < ActionDispatch::IntegrationTest
+      ##
+      # test all routes which lead to this controller
+      def test_routes
+        assert_routing(
+          { :path => "/api/0.6/way/1/relations", :method => :get },
+          { :controller => "api/ways/relations", :action => "index", :way_id => "1" }
+        )
+        assert_routing(
+          { :path => "/api/0.6/way/1/relations.json", :method => :get },
+          { :controller => "api/ways/relations", :action => "index", :way_id => "1", :format => "json" }
+        )
+      end
+
+      def test_index
+        way = create(:way)
+        # should include relations with that way as a member
+        relation_with_way = create(:relation_member, :member => way).relation
+        # should ignore relations without that way as a member
+        _relation_without_way = create(:relation_member).relation
+        # should ignore relations with the way involved indirectly, via a relation
+        second_relation = create(:relation_member, :member => way).relation
+        _super_relation = create(:relation_member, :member => second_relation).relation
+        # should combine multiple relation_member references into just one relation entry
+        create(:relation_member, :member => way, :relation => relation_with_way)
+        # should not include deleted relations
+        deleted_relation = create(:relation, :deleted)
+        create(:relation_member, :member => way, :relation => deleted_relation)
+
+        get api_way_relations_path(way)
+
+        assert_response :success
+
+        # count one osm element
+        assert_select "osm[version='#{Settings.api_version}'][generator='#{Settings.generator}']", 1
+
+        # we should have only the expected number of relations
+        expected_relations = [relation_with_way, second_relation]
+        assert_select "osm>relation", expected_relations.size
+
+        # and each of them should contain the element we originally searched for
+        expected_relations.each do |containing_relation|
+          # The relation should appear once, but the element could appear multiple times
+          assert_select "osm>relation[id='#{containing_relation.id}']", 1
+          assert_select "osm>relation[id='#{containing_relation.id}']>member[type='way'][ref='#{way.id}']"
+        end
+      end
+
+      def test_index_json
+        way = create(:way)
+        containing_relation = create(:relation_member, :member => way).relation
+
+        get api_way_relations_path(way, :format => "json")
+
+        assert_response :success
+        js = ActiveSupport::JSON.decode(@response.body)
+        assert_not_nil js
+        assert_equal 1, js["elements"].count
+        js_relations = js["elements"].filter { |e| e["type"] == "relation" }
+        assert_equal 1, js_relations.count
+        assert_equal containing_relation.id, js_relations[0]["id"]
+      end
+    end
+  end
+end