DRY out group_stage_service_spec

spec/services/group_stage_service_spec.rb

@@ -6,26 +6,26 @@ RSpec.describe GroupStageService do
     @teams2 = create_list(:team, 4)
     @prepared_groups = Hash[1 => @teams1, 2 => @teams2].values
   end
-  describe '#generate_group_stage method' do
+  describe '#generate_group_stage' do
+    let(:prepared_groups_groupstage) do
+      GroupStageService.generate_group_stage(@prepared_groups)
+    end
+
     it 'returns a stage object' do
-      group_stage = GroupStageService.generate_group_stage(@prepared_groups)
-      expect(group_stage).to be_a(Stage)
+      expect(prepared_groups_groupstage).to be_a(Stage)
     end
 
     it 'returns a stage object with level -1' do
-      group_stage_level = GroupStageService.generate_group_stage(@prepared_groups).level
-      expect(group_stage_level).to be(-1)
+      expect(prepared_groups_groupstage.level).to be(-1)
     end
 
     it 'adds the provided groups to the stage' do
-      group_stage_teams = GroupStageService.generate_group_stage(@prepared_groups).teams
-      expect(group_stage_teams).to match_array(@prepared_groups.flatten)
+      expect(prepared_groups_groupstage.teams).to match_array(@prepared_groups.flatten)
     end
 
     it 'adds GroupScore objects for every team present in the group' do
-      group_stage = GroupStageService.generate_group_stage(@prepared_groups)
-      teams_in_group_scores = group_stage.groups.map { |g| g.group_scores.map(&:team) }.flatten
-      expect(teams_in_group_scores).to match_array(@prepared_groups.flatten)
+      expect(prepared_groups_groupstage.groups.map { |g| g.group_scores.map(&:team) }.flatten)
+        .to match_array(@prepared_groups.flatten)
     end
 
     it 'raises exception when given different sizes of groups' do