add tests for controllers and ActionCable channels; improve main backend docs

main-server/spec/controllers/api/matchmaking_controller_spec.rb

@@ -0,0 +1,41 @@
+require "rails_helper"
+
+RSpec.describe Api::MatchmakingController, type: :controller do
+  routes do
+    ActionDispatch::Routing::RouteSet.new.tap do |r|
+      r.draw do
+        delete "destroy", to: "api/matchmaking#destroy"
+      end
+    end
+  end
+
+  let(:user) { User.create!(nickname: "CaptainHook", password: "password123") }
+  let(:token) { JwtService.encode(user_id: user.id) }
+
+  describe "DELETE #destroy" do
+    context "when authenticated" do
+      it "cancels matchmaking for current user and returns success message" do
+        request.headers["Authorization"] = "Bearer #{token}"
+        expect(MatchmakingService).to receive(:cancel).with(user.id)
+
+        delete :destroy
+
+        expect(response).to have_http_status(:ok)
+        json = JSON.parse(response.body)
+        expect(json["message"]).to eq("Matchmaking cancelled")
+      end
+    end
+
+    context "when unauthenticated" do
+      it "returns 401 unauthorized and does not call cancel" do
+        expect(MatchmakingService).not_to receive(:cancel)
+
+        delete :destroy
+
+        expect(response).to have_http_status(:unauthorized)
+        json = JSON.parse(response.body)
+        expect(json["error"]).to eq("Unauthorized")
+      end
+    end
+  end
+end