End-to-end (E2E) testing is a vital practice for any software team looking to deliver high-quality, bug-free apps and websites. With the rapid pace of development today, having solid end-to-end testing is more crucial than ever.
In this comprehensive guide, we‘ll explore 7 key best practices I recommend you adopt for E2E testing in 2023 based on extensive research and experience. Applying these tips will help your team release software faster without compromising on quality. Let‘s dive in!
What Exactly is End-to-End Testing?
Before we get into the specific practices, let‘s quickly level set on what end-to-end testing refers to.
E2E testing evaluates your entire software application from start to finish under real-world usage conditions. The goal is to replicate how actual users will interact with the system when it‘s live.
This means testing the full workflow from the UI front-end to the database back-end. E2E tests validate that all the integrated components of your app work together as expected from the user‘s perspective.
Unlike unit testing which focuses on isolated modules, E2E testing aims to catch issues that arise from system-wide interaction and dependencies.
Properly implemented end-to-end testing is invaluable for ensuring software quality and readiness before deploying to production. Well-designed E2E tests can uncover bugs that unit and integration tests will miss.
According to recent surveys, E2E test automation is a top priority for DevOps teams today:
- 76% of teams report having end-to-end test automation in place.
- 83% of decision-makers are focusing on increasing their test automation coverage even further.
This reflects how crucial E2E testing is for engineering teams to deliver software quickly without quality concerns. Now let‘s get into the specific best practices you should apply.
Best Practice #1: Test Real-World User Journeys
The first and most important best practice is to model your E2E tests based on real-world user journeys. Consider the typical usage paths and workflows for your target personas.
These will likely include flows like user registration, login, search, checkout, payment, account management, and so on. Prioritize testing the happy paths, edge cases, and failure paths across these critical journeys from start to finish.
While testing just the sunny day scenarios is tempting, leaving out edge cases or failure handling paths will leave your software vulnerable to bugs from these less-common scenarios.
Stepping into the shoes of your users and imagining how they‘ll interact with each workflow will ensure your E2E tests provide maximum value.
Here are some examples of real-world user journeys and flows to test for different types of applications:
- Ecommerce site: Browse products → Add to cart → Registration → Checkout → Payment → Order confirmation
- Social media app: Login → Post update → Tag friends → Logout
- Ridesharing app: Login → Set pickup location → Request ride → Track driver → Rate driver → Payment → Logout
Make sure to test each step in these workflows along with associated edge cases, like missing fields or errors. Testing real journeys gives you confidence that core usage will work smoothly.
Best Practice #2: Leverage Realistic Test Data
The second key practice is to test with diverse, realistic data that mirrors your production environment. Using fake placeholder data seems to allow your initial E2E tests to pass, but often hides issues that will crop up later with real variability.
Consider generating test data that reflects the full spectrum of real usage – customer names, locations, email domains, varied order details, diverse products, and so on.
Advanced tools like test data generators can automatically create large test data sets for rigorous E2E testing. Masking techniques also let you safely use real production data.
Testing with realistic, diverse data will massively improve your team‘s confidence that the software will work as expected in the hands of users.
Here are some ideas to make your test data more realistic:
- Use a random name generator to create varied customer records with different name lengths, cultural origins, etc.
- Use real address data covering different countries, cities, zip code formats etc.
- For products, test different prices, weights, sizes, formats etc.
- Mirror the variability of real usage by generating test data across the full range.
- Mask and anonymize real production data to safely incorporate into tests.
Testing with data that reflects real-world diversity helps catch tricky edge case bugs before they impact customers.
Best Practice #3: Have Extensive Validation Checks
The third vital best practice is to incorporate extensive validation checks in your E2E tests. These verifications confirm that each test achieved the desired outcomes and left the system in an expected state.
For example, when a user submits a new order, your E2E test validations should check:
- Order appears correctly in backend database
- User account page reflects new order
- Admin portal shows pending order notification
- Confirmation email was triggered
- Payment correctly captured
- Inventory levels decremented
Having comprehensive validation ensures your E2E tests catch not just crashes, but also subtle bugs related to workflows, data consistency, notifications, integrations, and more.
Aim to validate across backend databases, API responses, UI elements, logs, email / SMS, and any other components touched by the test. Adopt a "fail fast" mindset driving validation checks that will break on any unexpected result.
Research shows that tests having more validations directly translate into higher defect detection rates. Skimping on test validation leaves bugs lurking in your software.
Best Practice #4: Handle Edge Cases and Failures
While testing the happy path user journeys is crucial, robust E2E testing also requires validating behavior for edge cases and failures.
Edge cases represent usage outside the normal bounds – things like very large or small inputs, unused legacy features, old customer data, hitting API rate limits, etc.
Failures represent scenarios where components fail or behave unexpectedly – network blips, unavailable services, incorrect user inputs, high traffic loads, expired credentials, and so on.
Testing these messy real-world scenarios beyond the happy paths is key for delivering resilient software that degrades gracefully in production.
Make sure you account for relevant edge cases and failure modes based on your application architecture and environment.
Here are some examples of edge cases and failures to test for:
- Submit extra long input fields that exceed max database limits
- Make API requests with invalid authentication tokens
- Test behavior with DNS or network failures
- Shut down an external service dependency mid-test
- Pass malformed input data outside expected formats
- Trigger throttling / rate limits on external APIs under test
Testing these scenarios will help bulletproof your application for the complexity of real-world usage.
Best Practice #5: Test Across Environments
The fifth key practice is to execute your tests across different environments – not just locally on a developer machine.
Different environments like QA, staging, production, etc. have their own configuration quirks, dependencies, and data characteristics. Issues affecting production could be hidden during local testing.
Aim to test across your pipeline environments continuously on every code change to catch issues before they reach customers. Testing pre-production environments also validates deployment procedures.
Additionally, verify behavior across different operating systems, browsers, devices and network conditions. Finding compatibility issues early prevents headaches down the line.
Here are some recommendations on testing across environments:
- Spin up cloud infrastructure matching production topology for realistic testing.
- Test against different database versions – e.g. MySQL, Postgres, etc.
- Shift API or UI URLs between environments to confirm config changes propagate.
- Test on mobile, tablet, and desktop browsers like Chrome, Safari, Firefox.
- Mimic slow 3G network connections with network shaping tools.
- Test iOS and Android apps on a range of physical device types.
Covering more environments and conditions will help you identify issues that could impact a subset of your users in production.
Best Practice #6: Automate and Re-Run E2E Tests
Executing E2E testing manually is extremely time-consuming, repetitive, inconsistent, and prone to human error.
The sixth vital best practice is to fully automate your end-to-end tests using frameworks like Cypress, Selenium, Playwright, or proprietary tools.
With automation, you can execute test suites quickly, frequently, and reliably. Developers can run tests locally before committing code to get rapid feedback.
Automated E2E tests also facilitate continuous integration and deployment. Tests can execute on every code change to immediately catch any regressions.
By removing manual testing overhead, teams can afford more extensive test coverage running continuously. Automation also improves consistency over human execution.
Make sure to properly document and organize your test scripts for easy debugging, enhancement, and reporting.
Here are some stats showing the benefits of test automation:
- Teams with over 50% test automation achieve app release frequencies 5x higher than those below 50%
- 75% of teams report test automation provides ROI in less than 3 months
- 60% improvement in testing coverage when teams shift to automation
The data shows that taking the time to build automated E2E tests delivers massive benefits for software teams.
Best Practice #7: Adopt Continuous Testing
The final best practice is to truly adopt a culture and mindset of continuous testing. Look to deeply integrate automated E2E tests into developer workflows.
The goal is to run end-to-end tests early and often, with each code change, rather than only before major releases. Finding and fixing bugs as they are introduced is much faster and cheaper.
Treat your E2E test suites as living code that evolves in sync with your application features. As the UI changes, keep the tests up-to-date to catch any regressions.
Promote E2E testing as a shared responsibility across the team. Merge test automation skills into developer workflows for greater velocity and quality.
Here are some principles to keep in mind:
- Empower developers to own testing by providing automated E2E frameworks.
- Foster a culture where adding tests for new features is as important as writing the code.
- Continuously generate new automated tests to improve coverage over time.
- Make running test suites a required step before any production deployment.
Adopting a culture of true continuous end-to-end testing requires investment and discipline – but pays off tremendously in delivering great software.
Let‘s recap the top E2E testing best practices covered in this guide:
|Test real-world user journeys||Prioritize testing critical workflows from the user perspective|
|Leverage realistic test data||Use diverse test data mirroring production variability|
|Extensive validation checks||Confirm outcomes across all components touched by tests|
|Handle edge cases and failures||Test beyond the happy paths to catch tricky bugs|
|Test across environments||Execute tests in all target deployment environments|
|Automate tests||Re-run tests quickly, reliably using automation frameworks|
|Adopt continuous testing||Make E2E testing an integrated, ongoing practice|
Applying these recommendations will help your E2E testing strategy deliver the confidence required to release high-quality software quickly.
These tips represent proven practices distilled from top technology teams to maximize testing value and efficiency. I hope you find them useful!
As our industry keeps evolving, our testing practices need to evolve continuously as well. I recommend periodically evaluating your E2E testing methodology against these best practices to identify areas for improvement.
Investing in robust, automated end-to-end testing delivers huge payoffs in enabling your team to build outstanding software.
Let me know if you have any other questions! I‘m always happy to chat more about E2E testing strategies.