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

main-server/spec/channels/application_cable/connection_spec.rb

@@ -0,0 +1,44 @@
+require "rails_helper"
+
+RSpec.describe ApplicationCable::Connection, type: :channel do
+  include ActionCable::Connection::TestCase::Behavior
+
+  let(:user) { User.create!(nickname: "CaptainCook", password: "password123") }
+  let(:token) { JwtService.encode(user_id: user.id) }
+
+  describe "#connect" do
+    it "connects successfully with token in query params" do
+      connect "/cable", params: { token: token }
+      expect(connection.current_user).to eq(user)
+    end
+
+    it "connects successfully with Bearer token in Authorization header" do
+      connect "/cable", headers: { "Authorization" => "Bearer #{token}" }
+      expect(connection.current_user).to eq(user)
+    end
+
+    it "rejects connection when no token is provided" do
+      expect { connect "/cable" }.to have_rejected_connection
+    end
+
+    it "rejects connection when token is invalid" do
+      expect {
+        connect "/cable", params: { token: "invalid.jwt.token" }
+      }.to have_rejected_connection
+    end
+
+    it "rejects connection when token is expired" do
+      expired_token = JwtService.encode(user_id: user.id, exp: 1.hour.ago.to_i)
+      expect {
+        connect "/cable", params: { token: expired_token }
+      }.to have_rejected_connection
+    end
+
+    it "rejects connection when user does not exist in the database" do
+      orphan_token = JwtService.encode(user_id: 999_999)
+      expect {
+        connect "/cable", params: { token: orphan_token }
+      }.to have_rejected_connection
+    end
+  end
+end