When discussing the impact of unit tests on project budgets, the conventional wisdom suggests they represent an upfront investment that yields long-term returns. While achieving comprehensive test coverage across an entire project or specific modules is crucial for realizing these benefits, I’d like to explore scenarios where unit tests can actually accelerate development rather than simply serving as an investment.

Challenging traditional Unit Testing perspectives in PHP

The PHP ecosystem offers unique considerations when it comes to unit testing. We operate in an environment of immediate change visibility – without the need for building or compilation steps. This raises important questions:

• In MVP development, why invest in tests when product viability is uncertain?
• How do we balance testing with clients’ needs for rapid market entry?

Should we consult using UnitTests with business?

The answer isn’t straightforward. While there’s no need to discuss specific technical implementations with non-technical clients who rely on your expertise, we must always align our development approach with business objectives. Sometimes, circumstances may require prioritizing speed to market over comprehensive testing, particularly when racing against competitors or validating product concepts. While there’s abundant literature on managing technical debt, the key is preventing its accumulation from becoming standard practice.

However, there are specific scenarios where implementing unit tests can actually accelerate solution delivery compared to foregoing them entirely.

Strategic testing scenarios

Checkout process implementation

Consider the checkout process, which typically involves multiple pages and complex user interactions. Testing scenarios for both logged-in and guest users across various shipping options can consume significant development time.

Let’s examine a common scenario: sending order data to an ERP system. The payload must include product information, user data, shipping details, and payment information. Consider these variables:

• Three product types: Virtual, Configurable, and Simple
• Two delivery options based on cart contents (regular shipping and electronic delivery)
• Two checkout scenarios (logged-in user and guest)

This creates at least six distinct scenarios to verify code functionality across various combinations of products, delivery options, and authentication states – not including different payment methods. Unit tests allow you to validate code reliability without repeatedly going through the entire checkout flow manually.

Working with external integrations

The previous ERP example extends to any integration requiring complex API payloads or webhook handling. When working with external systems, several time-consuming challenges emerge:

Incomplete data in external systems

Often, you must begin integration with minimal external system configuration. Only credentials working, and you are lucky when there are a couple of items configured on the external system. You can use PHPUnit to prepare your system to handle all potential product types / payment types / customer types etc. It’s more than certain that some of your assumptions will not be valid, but you will have the majority of code ready and covered with unit tests, which will allow you to flexibly adapt to new data when it will be filled during the delivery cycle.

Data preparation for each test

External integrations frequently require coordination with client teams or third parties for test case preparation. Unit tests allow you to maximize each testing iteration by covering edge cases without waiting for integration test environments.

In this scenario, test cases will let you squeeze more from each round by adding edge cases in unit tests and being able to execute test suite multiple times without need, of waiting for integration test, and you may accomplish more in one round.

Working with time based algorithms

Systems often require time-dependent actions, such as abandoned cart notifications or post-purchase feedback requests. These typically depend on various conditions like user authentication status, marketing permissions, or campaign attribution. To test everything, what I can see among developers is prepared SQL scripts to map and modify database created_at, updated_at and many other fields to adapt the system to perform manual testing of application. A major problem with this solution is that it’s rarely updated on requirements and each developer have own set of such SQL queries.

Unit tests are an invaluable tool to support you in completing a task faster with additional documented system behavior controlled in the same repository as code exists. You will need to architecture the solution to be clean and testable, but that will not cost you much more than usual coding.

• Structure your code to separate business logic from framework and environmental details
• Design entry points using objects with dates and flags that determine system behavior
• Apply SOLID principles – separate message handling from decision-making logic
• Focus on business logic testing rather than queue execution systems

Code developed following these principles enables comprehensive testing of business logic through injected test scenarios. Manual testing can then focus on validating general data flow and messaging system functionality, while edge cases remain covered by unit tests.

Summary

Unit testing extends beyond achieving high coverage metrics or enabling CI/CD practices. When applied strategically, it becomes a powerful tool for accelerating development while maintaining quality. Ensure your projects have unit testing capabilities and proper pipeline integration from the start – this foundation will enable you to enhance development speed while improving code quality.