lick through the same login flow for the hundredth time, and you'll understand why developers started writing code to test code. That’s what automated testing is, in a nutshell. The basic idea is simple: instead of a person manually checking if your software works, you write a script that does the checking for you. Run that script, and it tells you what passed and what failed. No repetitive clicking required.

But automation isn't a replacement for good old fashioned manual testing. Each approach handles different problems well. Understanding when automated testing helps and when manual testing makes more sense is what matters. We'll break down what automated testing is, how it works, when to use it versus manual testing, and which tests are actually worth automating.

How does automated testing work?

Automated testing runs pre-written test scripts that interact with your software and check the results.

Here's a typical automated test in action:

1. Setup: The script launches your application and sets up any necessary test data
2. Execute: It performs specific actions – clicking buttons, entering text, navigating pages
3. Verify: It checks if the actual results match what you expected
4. Report: It logs what passed, what failed, and any errors encountered

Take a login test as an example. An automated script might open your login page, enter a username and password, click submit, then verify the user lands on the dashboard. Run that script, and you'll know within seconds if login still works. Run it across ten different browsers simultaneously, and you've just saved hours of checking.

The script executes the exact same steps every time. That consistency means it catches regressions reliably, but it also means the test only checks what you explicitly told it to check.

Automated testing vs manual testing: what's the difference?

The difference between automated testing and manual testing comes down to execution. Manual testing relies on human testers clicking, typing, and observing. Automated testing uses scripts to do the same work without human involvement.

Each approach has distinct strengths:

Manual testing handles:

• Exploring new features without a predetermined path
• Catching visual issues like misaligned buttons or odd color choices
• Adapting on the fly when something unexpected happens
• Evaluating whether something feels right to users
• Complex scenarios requiring judgment calls

Automated testing handles:

• Running hundreds of tests in minutes instead of days
• Testing the same scenarios repeatedly without variation
• Checking multiple browsers and devices simultaneously
• Catching regressions every time code changes
• Processing large volumes of data combinations

Automated tests will never notice that surprising edge case a manual tester might stumble across. But manual testers can't match automation's speed for repetitive regression checks. According to BrowserStack, the automation testing market exceeded $15 billion in 2020 and continues growing rapidly, largely because development cycles keep getting shorter.

Most teams use both. The question is less automated vs manual testing and more about what approach fits which situation. We talk more about manual vs automated testing here if you’re interested.

When should you use automated testing?

Automation needs significant upfront time investment. Writing automated tests takes much longer than creating manual test scripts, and maintaining them as your software changes takes ongoing effort. Automation only pays off when you'll run those tests often enough to make back that time investment.

Use automated testing for tests that run frequently, follow predictable patterns, and would be tedious to repeat manually. The best candidates for automation:

• Regression tests: When you fix a bug or add a feature, you need to verify existing functionality still works. Automated regression tests catch problems efficiently. These tests can run continuously during development, streamlining the entire release process.

• Repetitive scenarios: If you're testing the same login flow, search function, or checkout process for the twentieth time, automation saves considerable effort.

• Cross-browser and cross-device testing: Manually testing on Chrome, Firefox, Safari, Edge, plus various mobile devices takes days. Automated testing runs these checks in parallel.

• Performance and load testing: Simulating thousands of concurrent users isn't feasible manually. Automation reveals how your system behaves under pressure.

• API testing: APIs need testing with numerous parameter combinations. Automated testing handles this more efficiently than making manual API calls.

• Data-driven tests: When you need to run the same test with multiple data sets – different user types, payment methods, or input variations – automation makes sense.

When should you use manual testing?

Manual testing works better for tests that change frequently, require human judgment, or involve exploration and discovery.

Choose manual testing for:

• New or unstable features: Features under active development change too quickly for automation. Manual testing provides faster feedback without the overhead of maintaining brittle scripts.

• Exploratory testing: Testing without a predetermined script lets you follow interesting paths as you discover them. If clicking a button produces an odd result, you can immediately investigate why – something automated tests can't do. This adaptability helps uncover problems you didn't know to look for.

• Visual and usability checks: Does the page look right? Does the workflow feel intuitive? These subjective evaluations need human eyes and judgment.

• Complex user workflows: Some scenarios involve too many variables and decision points to script effectively. Manual testers can adapt as they go.

• One-off tests: If you'll only run a test once or twice, manual testing is faster than writing and maintaining automation.

• Initial verification: Before investing in automation, manually test new functionality to ensure it's stable and worth the automation effort.

Top tip...if maintaining automated tests takes more effort than just running manual tests, you're automating the wrong things.

What are the benefits of automated testing?

Automated testing saves time on repetitive tasks, gives faster feedback, and allows for more thorough coverage for regression checks. The main advantages of automated testing:

• Speed for repetitive checks: Automated tests run in minutes instead of hours or days. Computers can run tests 24 hours a day, seven days a week, transforming the scale at which testing operates. What takes a manual tester a week might finish overnight.

• Consistency: Scripts execute identically every time. No variation from tester fatigue, distraction, or forgetfulness. This reliability catches regressions systematically.

• Broader coverage for stable features: Automation lets you test scenarios that would be impractical manually – 50 different data combinations, 20 browser versions, overnight regression runs.

• Faster feedback on code changes: Automated tests integrated into your development pipeline give immediate feedback. Developers learn about problems within minutes, not days.

• Better resource allocation: Automation handles repetitive regression checks, freeing your testing team for exploratory testing, complex scenarios, and cases requiring human judgment.

• Cost efficiency over time: The upfront investment in automation tools and script development pays off when you run tests repeatedly.

What are the limitations of automated testing?

Automated testing solves specific problems well, but it has real limitations including:

• High upfront investment: Writing automated tests takes considerably longer than creating manual test scripts. You'll spend weeks or months building a test suite before seeing returns.

• Maintenance burden: Every time your software changes, your automated tests need updating. Features that change frequently means constant test maintenance.

• Can't evaluate user experience: Automated tests check if functionality works, but can't judge whether something feels intuitive or if the interface makes sense. They miss unclear error messages, confusing workflows, and visual inconsistencies.

• Lacks human intuition: Automated tests only find problems you anticipated. They can't explore interesting paths, react to unexpected behavior, or spot the kinds of issues that make a tester say "that's weird."

• Technical skills required: Building and maintaining automated tests often need some level of technical or event development expertise. Not everyone on your team can contribute.

The pragmatic approach to automated testing

Automated testing has its place, but it's only as effective as the time and money you put into setting it up – and it won't help you find the problems you didn't anticipate.

Our advice is to automate when it's cost-effective. Don't treat automation as the goal. Use it strategically where the time investment actually pays off, and keep manual testing as your primary tool for discovering the unexpected.

If you're going to automate, focus your efforts on:

• Core business functionality that absolutely can't break
• Tests you'll run dozens of times per release
• Checks requiring multiple configurations or large datasets
• Stable features that follow predictable patterns

Start small. Pick one genuinely repetitive test and see if automation saves you time. Don't build an automation suite because you think you should – build one because the math makes sense.

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