From https://once.com/writebook

test/controllers/users/profiles_controller_test.rb

@@ -0,0 +1,41 @@
+require "test_helper"
+
+class Users::ProfilesControllerTest < ActionDispatch::IntegrationTest
+  test "show" do
+    sign_in :david
+
+    get user_profile_url(users(:david))
+    assert_response :success
+
+    get user_profile_url(users(:kevin))
+    assert_response :success
+  end
+
+  test "edit is accessable to the current user" do
+    sign_in :david
+
+    get edit_user_profile_url(users(:david))
+    assert_response :success
+
+    get edit_user_profile_url(users(:kevin))
+    assert_response :forbidden
+  end
+
+  test "update modifies profile for current user" do
+    sign_in :kevin
+
+    put user_profile_url(users(:kevin)), params: { user: { name: "Bob" } }
+
+    assert_redirected_to users_url
+    assert_equal "Bob", users(:kevin).reload.name
+  end
+
+  test "update prohibits modifying profile of other users" do
+    sign_in :david
+
+    put user_profile_url(users(:kevin)), params: { user: { name: "Bob" } }
+
+    assert_response :forbidden
+    assert_equal "Kevin", users(:kevin).reload.name
+  end
+end