Unit Testing Swift Mobile App

Explore how to write small, self-contained unit tests in Swift that validate a function with valid and invalid inputs using the Xcode test framework and mocks, focusing on functionality.

Enable unit tests in an Xcode project by selecting include unit tests when creating a new project, or add a unit testing bundle and tests target to an existing project.

Discover how Xcode's default unit test case uses setup and teardown to initialize and clean up before each test, with class-level and instance-level distinctions and state sharing via static variables.

Explore ways to run unit tests in Xcode, using diamonds beside tests or test classes and the Test Navigator to selectively run, re-run, or run all tests.

Diagnose failing unit tests by inspecting test and app code, applying arrange-act-assert, and using Xcode's test failure breakpoint to locate and fix the is password valid bug, then rerun tests.

Apply test driven development to build a signup form validator for a mobile app, using unit tests first to validate first name, last name, and other fields before submission.

Write a unit test for a signup form modal validator to ensure a first name shorter than two characters is invalid, using arrange-act-assert and a should return false assertion.

Define and run a unit test to limit the first name to ten characters, implement the validation, and refactor constants into a dedicated sign up constants struct for reuse.

Apply test-driven development to implement and validate a user's last name, email, address, and password, using unit tests for valid and invalid inputs, boundaries, and negative scenarios.

Implement signup form request model in a Swift app, encapsulating first name, last name, email, and password, add a sign up method, and encode to JSON for a remote endpoint.

Create a url request, set http method to post, configure json headers, encode a form model to json using Encodable, and send the payload to create a new user.

Convert the response data into a signup response model using a JSON decoder, handle errors with a completion handler, and validate decodability with a unit test.

Inject a mock URL protocol into the signup web service's URL session to return predefined data, enabling controlled, unit-tested HTTP requests without hitting the network.

Continue implementing the sign up flow using the model view presenter design pattern, focusing on building and testing the presenter with mocked validator and sign up web service dependencies.

Create a signup presenter as the system under test. Pass a signup model to it and implement processUserSignup(formModel: SignupFormModel) to fix compilation and enable unit tests.

Create a validator protocol to unify mock and real implementations for unit testing, then conform both classes and inject the validator via initializer based dependency injection.

Tests verify that the presenter calls the view delegate's successful signup method using an expectation, with a mock signup view delegate and a signup view delegate protocol.

Inject the signup view delegate into the presenter using initializer based dependency injection, enabling unit tests to validate the signup flow with a delegate protocol and completion handling.

Demonstrate how to write a unit test to verify a signup button exists, is connected via an outlet, and has the correct action assigned on a view controller.

Learn how to unit test a signup button in a view controller by asserting that tapping the UIButton triggers the presenter’s signup method using a mock presenter with arrange-act-assert.

Refactor massive view controllers by splitting code into smaller, responsibility-focused classes. Enable isolated unit testing and maintainable architecture with patterns like MVP, MVVM, or VIPER.

Learn to safely extend an existing Swift method for unit testing by using parameter defaults and dependency injection to avoid breaking legacy code, and consider the decorator pattern.

Learn how to build and test view controllers that create views programmatically, including initializers and dependency injection, and load them in unit tests like storyboard and interface-file controllers.