Best practices for building end-to-end front-end test cases

Frequent and appropriate testing is a shield that deflects the impact of a development error before it harms the digital user experience you aim to provide. But writing robust test cases requires an investment of time and strategic thinking, more so because tests need to be structured thoughtfully. Maintaining tests can also be challenging as the code evolves. However, by following these best practices (for automated and manual testing processes) and refactoring relentlessly, you can reap the benefits of quality front-end testing for years to come.

1. Structure the test cases logically

Your aim should be to structure tests in a way that makes sense for your application. Such test cases are easier to update, understand, and execute.

• Group test cases by feature or user journey

Organize test cases into suites that represent related features or user flows. For example, you can have suites like “Registration”, “Login”, “Searching”. This provides a clear grouping and helps you identify what business scenarios are covered.

• Separate common utilities

Extract any common test utilities, like login functions, into separate files that can be imported where needed. Don’t clutter test files with shared helpers.

• Create a consistent naming scheme

Use uniform nomenclature for tests, like “userCanRegister” or “successfulLogin”. This makes it easier to document the test cases and scan through them and retrieve them when they are needed.

2. Isolate test cases

Each test case should focus on a specific piece of functionality and be independent of other tests. Isolated test cases give you greater confidence that each test validates the specific component it targets. It also helps with determining the root cause of a bug quickly.   

Here’s how you can isolate test cases. 

• Don’t rely on shared data between test runs. Reset state before and after each test.
• Stub out API calls or external services with mocking libraries. This isolates the front-end code being tested.
• If there are dependencies between tests, order them appropriately so each test has the expected starting state.

3. Leverage page objects for testing UI interactions

Page objects are reusable classes that represent UI pages or components. They encapsulate UI selectors and provide an API for common interactions.

For example, you can have a LoginPage class with a login() method handling the login form submission. Use this page object across multiple tests.

Page objects make tests far more maintainable. Updating a selector in one place fixes all tests. Without them, you risk duplicating selectors everywhere.

4. Verify the test outcomes visually with screenshots

Use pixel-by-pixel screenshot comparisons to check if your UI renders correctly after actions. This catches visual regressions during refactors. Create test cases that can take screenshots of page states and compare them to existing baseline images. Flag any pixel differences as test failures.

Visual testing is invaluable for verifying styling and layout. However, balance it with other assertions validating functionality and behavior.

5. Prioritize happy path test cases

Start by testing the happy paths – the most common successful scenarios and flows. Get these working properly first before diving into edge cases.

For example, first test if:

• Users can register successfully by filling the form properly
• Login succeeds with valid credentials
• Search returns expected results for normal queries

This way, you can gain confidence in the core user journeys before testing less-frequent paths.

6. Validate back-end integrations

You need to verify that front-end interactions correctly integrate with any back-end services and data sources. Testing front-end and back-end integrations end-to-end gives you greater coverage of the full stack working together.

• Spy on network calls

Spy on network requests to confirm the right API endpoints are hit with the expected data when actions are performed.

• Handle responses

To isolate front-end handling, mock back-end responses with sample data. Then validate that the front-end elements are processing the response properly.

• Operate on test databases

Check the test case queries on separate test databases seeded with data, rather than production ones. You can clean up data at the end.

7. Account for asynchronous actions

Modern front-end apps use asynchronous techniques like promises, calls backs, and requests. You must handle these properly in tests.

• Wait for promises and requests to resolve

Use built-in utilities that wait for pending async actions to complete before executing assertions.

For example, with Cypress you can write cy.get(‘.status’).should(‘contain’, ‘Updated’) to wait until the “.status” element contains the text “Updated” from an async request.

• Don’t rush assertions

Put assertions in then() blocks or await them so they run after async operations finish. Don’t assert immediately.

Testing asynchronous flows correctly prevents flakiness and false test failures.

8. Use auto-waiting capabilities

Many test runners like Cypress have auto-wait capabilities built-in to simplify handling async actions. For example, use commands to automatically retry and wait for elements to exist before acting on them.

Leverage auto-wait functionality rather than hard coding waits and timeouts yourself. This reduces waits and makes tests more reliable.

9. Add variations with test data

You want tests with different input data to cover different code paths and execution flows. So, make sure to test both valid and invalid data. This tests both success and failure handling.

For example, submit valid and invalid emails, passwords, etc. to test all validation scenarios.

Also, use realistic data variations, like different email domains, lengths, special characters, etc. to hit different validation rules. You can also vary the order of actions users might do. Doing A then B may hit different code than B then A. Testing with such diverse data makes your tests more robust.

10. Handle test data carefully

Beware of test cases that may interact with and mutate shared data sources like databases. Otherwise, you may pass the feature with fragile use cases that depend on precise data. Run tests on separate test databases with their own seeded sample data.If tests make permanent changes like inserting records, make sure to clean up and delete those records after each test finishes.

11. Implement robust test reporting

Thorough reporting helps you improve test quality and catch issues early.

• Track useful metrics like pass %, failure counts, test duration.
• Include test reporting in your continuous integration and delivery pipelines. 
• Add stack traces, screenshots, videos, etc. to help website developers pinpoint failures.
• Configure alerts on failures like Slack or email notifications so teams can respond quickly.
• Use reporting tools to get valuable insights into test metrics, failures, and trends.

12. Refactor tests ruthlessly

As the app changes, relentlessly refactor test cases to keep them maintainable. Don’t let them accumulate dead code and complexity. For instance, as iOS 17 and watchOS 10 upgrades have been launched, most businesses will update their solutions. Test cases for such solutions must evolve as well. 

Doing this keeps tests lean, clean, and reliable over the long term.

• Delete redundant helper methods, data providers, etc. that are no longer needed after changes.
• Watch for repeated code patterns and extract them into shared helpers and custom commands.
• Delete unreliable tests with sporadic failures you can’t resolve. They waste time and obscure real bugs.

Note: These front-end testing tips may not work in the absence of an apt understanding of the underlying framework on which said web or app solution is built. You should ideally have a team to make sense of the situation, so they can make the most of these suggestions and ensure a reliable testing environment for your application. If such a team is not a feasible choice for your business at present, you may consider hiring a web development company for QA. If you need help picking, you can check out these top app development companies in India [Clutch Rating and Google Ranking Verified].

Conclusion

Implementing comprehensive front-end testing with these best practices will transform your confidence in releasing changes. With these tips, you can craft front-end tests that act as a safety net by validating critical functionality and catching regressions. Your users will appreciate the increased stability and quality. 

Read more: Why Is Performance Testing Critical For Businesses?