diff --git a/Makefile b/Makefile
index 8b36344..10113ea 100644
--- a/Makefile
+++ b/Makefile
@@ -11,7 +11,8 @@ endif
 
 .PHONY: help dev-cli prod-cli \
         dev-up dev-down dev-up-rebuild \
-        prod-up prod-down prod-up-rebuild
+        prod-up prod-down prod-up-rebuild \
+        test test-watch test-coverage
 
 help:
 	@echo "Available targets:"
@@ -23,6 +24,9 @@ help:
 	@echo "  make prod-up                           # docker compose --profile prod up -d"
 	@echo "  make prod-up-rebuild                   # docker compose --profile prod up -d --build"
 	@echo "  make prod-down                         # docker compose --profile prod down"
+	@echo "  make test                              # Run backend tests"
+	@echo "  make test-watch                        # Run backend tests in watch mode"
+	@echo "  make test-coverage                     # Run backend tests with coverage report"
 	@echo "Notes: GNU Make nie wspiera subkomend z odstępami (np. 'make prod up')."
 	@echo "       Użyj odpowiednich celów z myślnikiem."
 
@@ -52,3 +56,13 @@ prod-up-rebuild:
 
 prod-down:
 	$(COMPOSE) --profile prod down
+
+# Tests
+test:
+	$(COMPOSE) exec $(BACKEND_SVC) npm test
+
+test-watch:
+	$(COMPOSE) exec $(BACKEND_SVC) npm run test:watch
+
+test-coverage:
+	$(COMPOSE) exec $(BACKEND_SVC) npm test -- --coverage
diff --git a/backend/src/__tests__/auth.test.js b/backend/src/__tests__/auth.test.js
index 2c6a1ef..c30ba2d 100644
--- a/backend/src/__tests__/auth.test.js
+++ b/backend/src/__tests__/auth.test.js
@@ -27,7 +27,7 @@ describe('Authentication API Tests', () => {
         .expect(201);
 
       expect(response.body).toHaveProperty('success', true);
-      expect(response.body).toHaveProperty('message', 'User registered successfully');
+      expect(response.body).toHaveProperty('message', 'User registered successfully. Please check your email to verify your account.');
       expect(response.body.data).toHaveProperty('user');
       expect(response.body.data).toHaveProperty('token');
       expect(response.body.data.user).toHaveProperty('id');
@@ -49,7 +49,7 @@ describe('Authentication API Tests', () => {
         .expect(400);
 
       expect(response.body).toHaveProperty('success', false);
-      expect(response.body).toHaveProperty('error', 'Email already registered');
+      expect(response.body).toHaveProperty('error', 'An account with these credentials already exists. Please try logging in or use different credentials.');
     });
 
     it('should reject registration with duplicate username', async () => {
@@ -64,7 +64,7 @@ describe('Authentication API Tests', () => {
         .expect(400);
 
       expect(response.body).toHaveProperty('success', false);
-      expect(response.body).toHaveProperty('error', 'Username already taken');
+      expect(response.body).toHaveProperty('error', 'An account with these credentials already exists. Please try logging in or use different credentials.');
     });
 
     it('should reject registration with invalid email', async () => {