UI Tests, The Missing Safety Net Your App Actually Needs
After 15+ years of iOS development, I’ve seen a curious pattern. Almost every codebase nowadays has unit tests. Very, very few have UI tests (Instrumented Tests in Android world). I believe this is costing companies more than they realize.
What are UI Tests?
UI tests are automated scripts that simulate real users interacting with your app. The tests tap buttons, type in textfields, open screens and verify that everything in your app works as expected. It’s like having a tireless QA person who checks every interaction in your app, every single time you make a change.
Unlike unit tests that check if your code logic is correct in isolation, UI tests verify that your actual app – the thing users interact with, works correctly. They catch problems users will actually experience: buttons that don’t respond, forms that won’t submit and screens that don’t load.
The Magic Button
Picture this. We’re about to launch a new feature within our app. We’ve developed this awesome new thing for the past 2 months and now it works as expected. However, as app core logic was slightly changed for this update to happen, we will need to have someone to go through every older section of our app and test if all old functionality stayed intact.
Not any more. I press a magic UI Test button and my screen suddenly fills with simulator clones spinning up. It’s like watching an army of invisible users attack the app. They go through screen by screen, feature by feature, element by element, exactly as real users would. They tap every button, type into every text field, open and close modals rapidly – almost like they’re trying to break things on purpose.
The simulators work through login flows, navigate to obscure settings screens, test that new feature we just build, but also check the old checkout flow we haven’t touched in years. They keep at it. They don’t get tired. They don’t skip anything that ‘should almost certainly work’.
Sometimes they find something, a regression bug in a completely different part of the app where we use a component we just modified for the new feature. The kind of bug would have slipped through because nobody things to manually test the profile screen when working on the shopping cart.
Sometimes everything passes. Green checkmarks appear after each test.
Either way, it feels like sorcery. This automated army gives us confidence that we haven’t broken anything with our latest changes. This is how our little startup ships features without a QA team or expensive testing services.
The Reality of iOS Testing
Walk into any iOS team and you’ll find developers who can debate testing patterns for hours. They’ll show you their impressiv unit test coverage. They’ll explain their mocking strategies. They’ve tested every edge case in their business logic.
Yet these same apps sometimes ship with broken login flows, unresponsive buttons or forms that crash on submission.
Your users don’t care that your data model is perfectly unit tested. They care that the app works when they use it. And what they use is the UI.
Why UI Tests Are the Real Safety Net
Here is what UI tests catch that unit tests never will:
- Regression in User Flows: That login flow you haven’t touched in six months? It broke when you updated a seemingly unrelated library.
- Integration issues: Your perfectly unit-tested network layer means nothing if the UI never updates when data arrives. UI tests verify the full stack works together.
- State management bugs: The cart shows 3 items, but checkout processes 2. Your unit tests pass because data model is fine. UI tests fail because they verify what users actually see.
- Device-Specific Problems: Your app works perfectly on the iPhone 15 Pro you test with, but on iPhone SE, half of your buttons are unreachable. UI tests running on multiple simulators catch this too.
The Economics Make Sense
Let’s be practical. Hiring a QA person or contractinga a company like Testlio can cost up to €60,000 a year and more. That’s for manual testing that’s repetitive, can lead to human error and doesn’t really scale.
UI tests are a one time investment that run thousands of times, for free, forever, any time you need them. Yes there’s initial setup time and yes there is maintenance. But compared to the alternatives it’s not even close what your company will be spending hiring a company or a QA engineer.
UI tests run every single time. They don’t get tired. They don’t skip tests when in a hurry. They catch regression bugs immediately, not after you’ve shipped to production.
Hidden Cost of Not Having UI Tests
Every production bug has a cost beyond just fixing it:
- Emergency hotfixes disrupt your roadmap
- Customer support dealing with bug reports
- Users who never come back after hitting a bug
- Negative reviews affecting your App Store ranking
One critical bug that UI tests would have caught can cost more than your entire investment in test automation.
The Bottom Line
If you’re a startup founder or CTO with an app, you’re making a choice every day. Either you’re paying for bugs in production through lost users, emergency fixes and damaged reputation, or you’re investing in prevention through UI tests.
I believe every app update without UI tests is a gamble. You’re betting that nothing broke, that all your old features will work, that your changes didn’t have unexpected side effects. Your competitors are one bad relese away from losing their users to you. But you’re also one bad release away from losing users to them. UI tests are your insurance policy against becoming another abandonware in the vast growing landscape of applications.
Tech is there and the ROI is clear. Your users deserve an app that works. Your company deserves the confidence that comes from testing. And you deserve to sleep better, knowing that your next release won’t break old features.
