# Run unit tests · A simple Chromia app with Rell and React · Learn Chromia > Once you have added input verification, running the tests produces failures with the message "User must sign this operation." Source: https://chromia.com/learn/my-news-feed/module-one/input-verification/tests/ A simple Chromia app with Rell and ReactLesson 15 of 27 1. [01Building a simple Chromia app with Rell, React and FT4](https://chromia.com/learn/my-news-feed/introduction/) 2. [02Project setup complete](https://chromia.com/learn/my-news-feed/setup/) Module 1: A Rell backend with FT accounts 1. [03Overview](https://chromia.com/learn/my-news-feed/module-one/) 2. [04Part 1: Designing the database schema](https://chromia.com/learn/my-news-feed/module-one/data-modeling/) 3. [05The data model](https://chromia.com/learn/my-news-feed/module-one/data-modeling/tables/) 4. [06Code the model in Rell](https://chromia.com/learn/my-news-feed/module-one/data-modeling/model/) 5. [07Part 2: Set up accounts](https://chromia.com/learn/my-news-feed/module-one/create-accounts/) 6. [08FT4 accounts configuration](https://chromia.com/learn/my-news-feed/module-one/create-accounts/install-configure-ft4/) 7. [09Authentication with FT4 accounts](https://chromia.com/learn/my-news-feed/module-one/create-accounts/authentication/) 8. [10Part 3: A closer look at operations and queries](https://chromia.com/learn/my-news-feed/module-one/operations-queries/) 9. [11Basic operations](https://chromia.com/learn/my-news-feed/module-one/operations-queries/basic-operations/) 10. [12Basic queries](https://chromia.com/learn/my-news-feed/module-one/operations-queries/write-queries/) 11. [13Part 4: Validating and verifying input](https://chromia.com/learn/my-news-feed/module-one/input-verification/) 12. [14Verify inputs](https://chromia.com/learn/my-news-feed/module-one/input-verification/input-verification/) 13. [15Run unit tests](https://chromia.com/learn/my-news-feed/module-one/input-verification/tests/) 14. [16Part 5: How the dapp project is organized](https://chromia.com/learn/my-news-feed/module-one/project-structure/) 15. [17Work with Rell modules](https://chromia.com/learn/my-news-feed/module-one/project-structure/modules/) 16. [18Add modules to your dapp](https://chromia.com/learn/my-news-feed/module-one/project-structure/incorporate-modules/) 17. [19Part 6: Sign up users with an EVM wallet](https://chromia.com/learn/my-news-feed/module-one/register-evm-accounts/) 18. [20Sign up accounts with EVM wallets](https://chromia.com/learn/my-news-feed/module-one/register-evm-accounts/register-evm-accounts/) 19. [21Test the registration](https://chromia.com/learn/my-news-feed/module-one/register-evm-accounts/test-registration/) Module 2: The React project 1. [22Overview](https://chromia.com/learn/my-news-feed/module-two/) 2. [23Set up the project](https://chromia.com/learn/my-news-feed/module-two/setup/) 3. [24Project scaffold](https://chromia.com/learn/my-news-feed/module-two/scaffold/) 4. [25Connect the client](https://chromia.com/learn/my-news-feed/module-two/connecting-the-client/) 5. [26Summary and manual testing](https://chromia.com/learn/my-news-feed/module-two/summary-and-tests/) 1. [27What is next?](https://chromia.com/learn/my-news-feed/what-next/) [Learn](https://chromia.com/learn/)[A simple Chromia app with Rell and React](https://chromia.com/learn/my-news-feed/) 15 / 27Module 1: A Rell backend with FT accountsBeginner # Run unit tests Once you have added input verification, running the tests produces failures with the message "User must sign this operation." This is the expected result: the original tests never signed their transactions, so the new checks reject them. To make the tests pass, sign each test transaction with `.sign(keypair)`. In `test_create_entities`, for example, Alice's keypair signs the transaction: src/test/news\_feed\_test.rell ``` val alice_kp = rell.test.keypairs.alice; // <-- function test_create_entities() { rell.test.tx() .op(create_user("Alice", alice)) .op(create_user("Bob", bob)) .run(); assert_equals(user @ { } ( @sum 1 ), 2); rell.test.tx() .op(ft_auth_operation_for(alice)) .op(follow_user(bob)) .op(ft_auth_operation_for(alice)) .op(make_post("My post")) .sign(alice_kp) .run(); assert_true(is_following(alice, bob)); assert_equals(follower @ { } ( @sum 1 ), 1); assert_equals(post @ { } ( @sum 1 ), 1); rell.test.tx() .op(ft_auth_operation_for(alice)) .op(unfollow_user(bob)) .sign(alice_kp) .run(); assert_equals(follower @ { } ( @sum 1 ), 0); } ``` The second test, `test_follower_calculation`, needs a signature on its transaction as well: src/test/news\_feed\_test.rell ``` function test_follower_calculation() { ... rell.test.tx() .op(ft_auth_operation_for(alice)) .op(follow_user(bob)) .op(ft_auth_operation_for(alice)) .op(follow_user(charlie)) .sign(alice_kp) // <-- .run(); ... } ``` The last test involves two users. Alice signs the `follow_user` transaction, and Bob signs the `make_post` transactions. Add a constant for Bob's keypair and update the test as shown: src/test/news\_feed\_test.rell ``` val bob_kp = rell.test.keypairs.bob; function test_pagination_of_posts() { rell.test.tx() .op(create_user("Alice", alice)) .op(create_user("Bob", bob)).run(); rell.test.tx() .op(ft_auth_operation_for(alice)) .op(follow_user(bob)) .sign(alice_kp) // <-- .run(); for (i in range(5)) { rell.test.tx().op(make_post(bob, "Content %d".format(i))).sign(bob_kp).run(); // <-- } ... } ``` With these changes, every test passes. ## Additional testing Add one more test to verify that a user cannot impersonate another user and that input validation behaves correctly: src/test/news\_feed\_test.rell ``` val charlie_kp = rell.test.keypairs.charlie; function test_input_verification() { rell.test.tx() .op(create_user("Alice", alice)) .op(create_user("Bob", bob)).run(); // Bob cannot impersonate alice rell.test.tx() .op(ft_auth_operation_for(alice)) .op(follow_user(bob)) .sign(bob_kp) .run_must_fail(); rell.test.tx() .op(ft_auth_operation_for(alice)) .op(make_post("My malicous post")) .sign(bob_kp) .run_must_fail(); // Alice cannot follow non-existing charlie val f1 = rell.test.tx() .op(ft_auth_operation_for(alice)) .op(follow_user(charlie)) .sign(alice_kp) .run_must_fail(); assert_true(f1.message.contains("does not exist")); // Charlie cannot create post since he does not exist val f2 = rell.test.tx() .op(make_post("My secret post")) .sign(charlie_kp) .run_must_fail(); assert_true(f2.message.contains("Expected at least two operations")); } ``` You now know how to apply basic input validation to queries and operations. The next module covers more secure, structured account management with the [ft-library](https://docs.chromia.com/build/ft4/intro/). Written for this site from Chromia’s public course. Code samples are the course’s own. [← Previous**Verify inputs**](https://chromia.com/learn/my-news-feed/module-one/input-verification/input-verification/)[Next →**Part 5: How the dapp project is organized**](https://chromia.com/learn/my-news-feed/module-one/project-structure/) On this page * [Additional testing](#additional-testing)