Jim’s heart raced as he watched the CEO’s eyes flare with frustration. Their mobile app had just frozen mid-demo in front of investors. As sweat beaded on his forehead, Jim braced for the aftermath — he was the CTO, after all. He knew this mess could have been avoided if he had listened to the engineers about thorough automated testing.

Over the past months, Jim and the CEO had brushed off requests from the engineering team to add automated unit and integration tests. They insisted testing would only slow down their rapid development cycle without bringing real value to the product.

But without an adequate safety net, quality was bound to crumble. Each code change introduced new bugs that destabilized existing features.

Jim’s story is typical among teams who dismiss testing as unnecessary. Eventually, the technical debt compounds until the entire app unexpectedly fails one day.

As someone who has pushed many reluctant teams to adopt testing, I truly believe automated tests are critical for anyone who cares about stability, velocity and innovation.

Why Automated Tests Are Important

Here are the top reasons your team needs to prioritize testing.

Tests Safeguard Against Disasters

Like a net for trapeze artists, a strong set of automated tests prevents catastrophic failures down the line. Unit tests detect bugs early before they ruin your big event.

While manual QA helps, it can’t fully protect against defects reaching users. Tests provide an essential line of defense as code evolves rapidly.

Tests Enable Confident Delivery

For large projects with many developers, testing ensures velocity without sacrificing quality. The amount of bugs QA reports without automated tests on a decent project is insurmountable and demotivating.

With automated regression and integration tests, developers can fearlessly make changes, knowing most issues get caught quickly. Testing fuels innovation.

Tests Slash Debugging Time

Numerous studies have shown that extensive testing reduces overall debugging time — in some cases by 50% or more!

By preventing bugs upfront, less time is wasted reproducing and pinpointing root causes. Higher quality means fewer Friday night fire drills.

Tests Clarify Requirements

A good test suite provides living documentation showing precisely how different parts of the code should function. The key here is “good”.

Tests serve as detailed specifications that onboard new developers faster. They provide clear examples that simplify complex codebases.

Cautionary Tales

While the benefits seem clear, some teams still make the mistake of underprioritizing testing. Here are some scary examples:

  • A financial services firm lost $440 million in 45 minutes after deploying untested trading software that behaved erratically.
  • An Airplane software glitch grounded an entire airline fleet. Hundreds of flights were delayed, thousands of people were frustrated, and millions of dollars were lost.
  • A shopping cart bug allowed users to purchase items below cost, losing an e-commerce company $10 million overnight.

These kinds of catastrophic failures can be prevented with sufficient automated testing practices.

Why Teams Avoid Testing

Despite the benefits and the scary stories, many teams would rather avoid adding tests, seeing it as a wasted effort. Here are some common excuses:

  • No time for writing tests. Well, fixing bugs that pop up after every code commit without tests takes even longer. You should prioritize writing tests to move faster.
  • The codebase is too messy to test. That’s exactly why you need tests before changing it further. Start writing tests for critical paths and increase coverage gradually.
  • Testing seems too hard; we don’t know where to begin. You can ramp up with training and hiring someone from the outside who has the expertise. Start simple — small steps like smoke tests make a big difference and are usually easy to write.

Types of Tests

Let’s quickly cover what types of automated tests you should have.

Unit Tests

Unit Tests validate individual functions and classes in isolation. For example, you may unit test a utility function that formats a phone number. The test would validate it correctly formats numbers like “(555) 123–4567”.

Unit testing is critical because functions are the building blocks of applications. If small units of code have bugs, they propagate outward into more significant problems. Failing to catch issues early leads to surprising bugs and painful debugging down the road.

Dev teams should make unit testing mandatory before any code is merged. Target at least 70% unit test coverage as a goal.

Integration Tests

Integration Tests verify interactions between modules and services. For instance, you may integration test your authentication service by having it call your database module to validate credentials.

Integration testing confirms different components work together as expected. Without it, modules that function independently may still fail when integrated, which results in difficult-to-trace bugs.

Build integration test suites that run automatically on code changes. Use stubbing and mocking to isolate services. Record test scenarios in CI/CD pipelines before deployment. Integration testing is important for complex distributed systems but more complicated and time-consuming than unit testing.

End-to-End Tests

End-to-end tests simulate production usage by interacting with the app like real users. For a web app, you may click buttons, fill in forms, and assert page content appears correctly.

E2E testing reveals bugs that only occur under specific user flows. Unit and integration tests miss these since they lack UI and networking layers. Without sufficient end-to-end testing, user experience suffers.

Use frameworks like Selenium and Cypress to automate browser testing. Have E2E tests run on pre-production environments continuously. These tests require the most effort to write and maintain, especially in rapidly evolving products, and they can be substituted with manual QA for the time being. They are important, though, cause E2E testing builds confidence for users.

Starting Your Testing Journey

Ready to get your team on board? Here are proven ways to introduce testing.

Start Small

Start small by adding tests for your most critical user flows like signup and checkout. For example, thoroughly test validating user inputs on a signup form before creating an account.

Focusing on critical paths first allows you to reap benefits without getting overwhelmed. Flaky tests on critical workflows undermine overall confidence. Build a solid foundation before broadening the scope.

Identify 2–3 core user journeys similar to signup. Get developers to eat their own dog food by fixing tests before moving on.

Mandate Tests for Bugfixes

Mandate tests for all bug fixes to prevent regressions. For instance, if a bug is found where clicking “Submit” erroneously clears form fields, add a test validating that data in the fields persists.

Bugs often get reintroduced if existing tests miss them the first time. Tests prevent repetitive defects and whack-a-mole. Not testing fixes costs more in the long run.

Institute zero tolerance for fixing bugs without corresponding tests. Tests protect your users and your time.

Gradually Increase Coverage

Increase coverage X% each sprint. Track with code coverage tools. For example, commit to improve coverage by 5% each sprint.

Incremental coverage goals maintain focus on testing. Visibility motivates developers. In turn, stagnant coverage leads to technical debt building up.

Use coverage tools and add badges to READMEs. Celebrate milestones!

Add Integration and UI Tests

Once solid unit coverage is achieved, add integration and UI tests. For instance, stub out database calls before replacing them with real integration.

Unit tests form a foundation, but integration and end-to-end testing reveal different classes of bugs. Taking a layered approach prevents gaps.

Make different testing levels visible using color-coded reports. Keep expanding the test pyramid as capabilities improve. Comprehensive testing is a journey.

High-quality software requires rigorous automated testing. Take it from my painful experience — the effort pays off exponentially in reduced bugs and faster delivery.

Avoid disaster stories like the ones I mentioned above by prioritizing testing. With consistency and focus, any team can leverage tests to accelerate innovation and delight users. The investment is beyond worth it.

Originally published on Medium.com