diff --git a/spec/interactors/add_group_stage_to_tournament_interactor_spec.rb b/spec/interactors/add_group_stage_to_tournament_interactor_spec.rb
new file mode 100644
index 0000000..ca126dc
--- /dev/null
+++ b/spec/interactors/add_group_stage_to_tournament_interactor_spec.rb
@@ -0,0 +1,55 @@
+# frozen_string_literal: true
+
+RSpec.describe AddGroupStageToTournament do
+  let(:empty_tournament_context) do
+    AddGroupStageToTournament.call(tournament: @empty_tournament, groups: @groups)
+  end
+
+  let(:group_stage_tournament_context) do
+    AddGroupStageToTournament.call(tournament: @group_stage_tournament, groups: @groups)
+  end
+
+  before do
+    @empty_tournament = create(:stage_tournament, stage_count: 0)
+    @group_stage_tournament = create(:group_stage_tournament)
+    @group_stage = create(:group_stage)
+    @groups = Hash[1 => create_list(:team, 4), 2 => create_list(:team, 4)].values
+  end
+
+  context 'GroupStageService mocked' do
+    before do
+      expect(class_double('GroupStageService').as_stubbed_const(transfer_nested_constants: true))
+        .to receive(:generate_group_stage).with(@groups)
+                                          .and_return(@group_stage)
+    end
+
+    context 'Empty tournament' do
+      it 'context succeeds' do
+        expect(empty_tournament_context).to be_a_success
+      end
+
+      it 'adds group stage to the tournament' do
+        test = empty_tournament_context.tournament.stages.first
+        expect(test).to eq(@group_stage)
+      end
+    end
+  end
+
+  context 'playoff generation fails' do
+    before do
+      expect(class_double('GroupStageService').as_stubbed_const(transfer_nested_constants: true))
+        .to receive(:generate_group_stage).with(@groups)
+                                          .and_return(false)
+    end
+
+    it 'context fails' do
+      expect(empty_tournament_context).to be_a_failure
+    end
+  end
+
+  context 'Tournament where group stage is already generated' do
+    it 'does not add group stage' do
+      expect(group_stage_tournament_context).to be_a_failure
+    end
+  end
+end