add controller tests

test/models/user_test.rb

@@ -2,7 +2,7 @@ require "test_helper"
 
 class UserTest < ActiveSupport::TestCase
   test "should be valid with an email and password" do
-    user = User.new(email: "test@example.com", password: "password123456")
+    user = User.new(email: "new-user@example.com", password: "password123456")
     assert user.valid?
   end
 
@@ -12,23 +12,23 @@ class UserTest < ActiveSupport::TestCase
   end
 
   test "should be invalid with a duplicate email" do
-    User.create(email: "test@example.com", password: "password123456")
-    user = User.new(email: "test@example.com", password: "password123456")
+    existing_user = users(:admin_user)
+    user = User.new(email: existing_user.email, password: "password123456")
     assert_not user.valid?
   end
 
   test "should have a default role of contributor" do
-    user = User.new(email: "test@example.com", password: "password123456")
+    user = User.new(email: "new-user@example.com", password: "password123456")
     assert user.contributor?
   end
 
   test "can be a reviewer" do
-    user = User.new(email: "test@example.com", password: "password123456", role: :reviewer)
+    user = User.new(email: "new-user@example.com", password: "password123456", role: :reviewer)
     assert user.reviewer?
   end
 
   test "can be an admin" do
-    user = User.new(email: "test@example.com", password: "password123456", role: :admin)
+    user = User.new(email: "new-user@example.com", password: "password123456", role: :admin)
     assert user.admin?
   end