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

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

@@ -0,0 +1,114 @@
+require "rails_helper"
+
+RSpec.describe Api::RegistrationsController, type: :controller do
+  describe "POST #create" do
+    context "with valid parameters" do
+      let(:valid_params) do
+        {
+          user: {
+            nickname: "CaptainNemo",
+            password: "secretpassword"
+          }
+        }
+      end
+
+      it "creates a new user and returns 201 with user data and JWT token" do
+        expect {
+          post :create, params: valid_params
+        }.to change(User, :count).by(1)
+
+        expect(response).to have_http_status(:created)
+
+        json = JSON.parse(response.body)
+        expect(json["token"]).to be_present
+        expect(json["user"]).to include(
+          "nickname" => "CaptainNemo",
+          "avatar_url" => nil
+        )
+        expect(json["user"]["id"]).to be_present
+        expect(json["user"]["created_at"]).to be_present
+
+        # Verify token is valid and decodes to created user
+        decoded = JwtService.decode(json["token"])
+        expect(decoded[:user_id]).to eq(json["user"]["id"])
+      end
+
+      it "attaches avatar and returns avatar_url when avatar is provided" do
+        avatar = fixture_file_upload(
+          Rails.root.join("spec", "fixtures", "files", "avatar.png"),
+          "image/png"
+        ) rescue Rack::Test::UploadedFile.new(
+          StringIO.new("\x89PNG\r\n\x1a\n\x00\x00\x00\rIHDR\x00\x00\x00\x01\x00\x00\x00\x01\x08\x06\x00\x00\x00\x1f\x15c4"),
+          "image/png",
+          original_filename: "avatar.png"
+        )
+
+        params_with_avatar = valid_params.deep_merge(user: { avatar: avatar })
+
+        post :create, params: params_with_avatar
+        expect(response).to have_http_status(:created)
+
+        json = JSON.parse(response.body)
+        expect(json["user"]["avatar_url"]).to be_present
+
+        user = User.find(json["user"]["id"])
+        expect(user.avatar).to be_attached
+      end
+    end
+
+    context "with invalid parameters" do
+      it "returns 422 unprocessable entity when nickname is missing" do
+        post :create, params: { user: { nickname: "", password: "password123" } }
+
+        expect(response).to have_http_status(:unprocessable_content)
+        json = JSON.parse(response.body)
+        expect(json["errors"]).to be_an(Array)
+        expect(json["errors"]).to include("Nickname can't be blank")
+      end
+
+      it "returns 422 unprocessable entity when password is too short" do
+        post :create, params: { user: { nickname: "CaptainNemo", password: "123" } }
+
+        expect(response).to have_http_status(:unprocessable_content)
+        json = JSON.parse(response.body)
+        expect(json["errors"]).to include("Password is too short (minimum is 6 characters)")
+      end
+
+      it "returns 422 unprocessable entity when nickname is already taken" do
+        User.create!(nickname: "CaptainNemo", password: "password123")
+
+        post :create, params: { user: { nickname: "captainnemo", password: "password123" } }
+
+        expect(response).to have_http_status(:unprocessable_content)
+        json = JSON.parse(response.body)
+        expect(json["errors"]).to include("Nickname has already been taken")
+      end
+
+      it "returns 422 when avatar has an unsupported content type" do
+        invalid_avatar = Rack::Test::UploadedFile.new(
+          StringIO.new("plain text content"),
+          "text/plain",
+          original_filename: "test.txt"
+        )
+
+        post :create, params: {
+          user: {
+            nickname: "CaptainNemo",
+            password: "password123",
+            avatar: invalid_avatar
+          }
+        }
+
+        expect(response).to have_http_status(:unprocessable_content)
+        json = JSON.parse(response.body)
+        expect(json["errors"]).to include("Avatar must be a PNG, JPEG, GIF or WebP image")
+      end
+
+      it "raises ParameterMissing when user param is omitted" do
+        expect {
+          post :create, params: {}
+        }.to raise_error(ActionController::ParameterMissing)
+      end
+    end
+  end
+end