Web Testing Strategies

Testing Strategies: Building a Reliable Test Suite

A good test strategy helps you catch bugs early, refactor with confidence, and ship faster. But not all tests are created equal, and testing everything is rarely the right approach. The key is to focus your testing effort where it provides the most value.

What to Test

Focus on testing your business logic — the parts of your code that make decisions and process data. A function that calculates shipping costs, validates user input, or applies business rules is a good candidate for testing. A function that simply passes data from the database to the UI might not need its own test.

Test the edges: what happens when the input is empty, null, or malformed? What happens when the database is unavailable? What happens when the user doesn't have permission? These edge cases are where bugs hide.

The Testing Trophy

The traditional testing pyramid (lots of unit tests, fewer integration tests, few E2E tests) has been refined by the testing trophy model. This approach emphasizes integration tests that test your application the way a user would use it, but without the flakiness of full browser tests.

Integration tests that test your API endpoints with a real database, or your React components with a real rendering environment, give you the most confidence per test. They catch the kinds of bugs that matter most — things don't work together properly — while being fast and reliable enough to run on every commit.

Writing Testable Code

Code that's easy to test is usually better designed. Functions that do one thing and have clear inputs and outputs are easy to test. Functions that depend on global state, make network calls, or have side effects are harder to test. Dependency injection — passing dependencies as parameters rather than creating them inside the function — makes code more testable.

Pure functions — functions that always return the same output for the same input and have no side effects — are the easiest to test. They don't require any setup, mocking, or cleanup. Try to structure your code so that business logic is in pure functions, separated from the infrastructure code that handles I/O.

Running Tests Effectively

A good test suite runs fast. If tests take too long, developers won't run them. Use in-memory databases for integration tests. Mock external services. Run unit tests on every file save. Run the full test suite in CI. And make sure test failures are clear — a failing test should tell you exactly what went wrong and where.

Test coverage is a useful metric, but it's not the goal. 100% coverage doesn't mean your application is bug-free. Focus on testing the critical paths and the edge cases. A few well-written tests are more valuable than many tests that just exercise code without meaningful assertions.