Let‘s start with a high level overview of these fundamental quality assurance techniques.
Bird‘s Eye View
Functional Testing examines an entire application similar to a real user. It serves to confirm the software works as expected across typical usage scenarios from beginning to end. You can think of it as taking the system on a test drive!
Unit Testing zooms into the components that make up an application and ensures each isolated unit functions properly. This serves as the foundation on which higher quality is built incrementally. Consider it as meticulously inspecting each part in an automobile.
While definitions may vary slightly across sources, the overarching purpose aligns – deliver software that meets user and business expectations by preventing, detecting and fixing defects with different testing scopes and techniques.
Interestingly, unit testing predates functional testing with origins in extreme programming techniques promoting test-first development. High quality was baked into each component as it was built.
Comparing Test Case Practices
Let‘s explore some examples of how test cases differ across these approaches. Consider an ecommerce website – popular user interactions like managing a shopping cart make great candidates.
A functional test would validate the full lifecycle:
- Search for a product
- Add item to cart
- Enter shipping address
- Select payment method
- Confirm order
Whereas, unit tests would focus on individual components across this workflow:
- Search text box allowing phrase entry
- Suggestions drop-down displaying results
- Button adding item to persistent cart
- Credit card field accepting 16 digit numbers
- Order confirmation page displaying details
Or for a calculator app:
Functional Test Cases
- Verify large equations execute properly
- Confirm operation order of precedence
- Validate results across multiple math functions
Unit Test Cases
- Numbers and decimal buttons working
- Individual operations like add/subtract/multiply/divide calculating accurately
- Clear button resetting fields/memory
Beyond front end UI flows, we also need to consider validation logic and backend integrations.
Best Practices for Maximizing Test Value
Firstly, functional test automation is essential for maintaining broad test coverage across user workflows to complement unit testing. Frameworks like Selenium (web), Appium (mobile), TestComplete (desktop) accelerate execution.
On unit testing side, mocking external services utilizing libraries like Mockito (Java) enables isolated component testing. Rather than requiring actual databases or networks, mock functionality simulates integrated behavior.
Additionally, tracking overall code coverage provides useful metrics for measuring test suite comprehensiveness. 80% statement coverage is a reasonable target for most applications. Instrumentation frameworks analyze test execution across software to highlight gaps.
Industry standards like ISO 29119 provide comprehensive guidelines spanning functional and unit test practices for validation of systems and software. Certification demonstrates commitment to quality.
Furthermore, given increased reliance on web/mobile apps, adding device/browser test coverage is imperative. Solutions like BrowserStack enable automated testing across thousands of real mobile devices and browsers supporting both functional UI flows and unit test cases.
Shifting Left with Test Driven Development
The growing DevOps movement aims to accelerate delivery of software innovation. A central shift left principle calls for testing to begin earlier, primarily via robust unit testing frameworks.
Research indicates following a test-driven development approach leads to:
- 50-60% reduction in defect density [1]
- 10-30% gains in developer productivity [2]
- Up to 80% improvement in test coverage [3]
The key idea focuses developer efforts on satisfying prescribed test cases versus just implementations that happen to work. This test-first mindset sets quality as the driver for all design and coding decisions.
In effect, the existence of unit tests serves as living documentation of intended component functionality in itself. Maintaining and expanding test suites creates built-in redundancy for key user interactions.
Optimal Balance
In closing, savvy development teams recognize the complementary synergies between functional and unit testing.
Comprehensive unit testing provides the foundation for stable, reliable software. Functional testing offers confidence products meet end user needs before release while also facilitating ongoing regression testing.
Blending both approaches addresses quality from the smallest code units through full system interactions to deliver exceptional finished applications.
Now that you have a firm grasp on comparing these techniques, it‘s time to start testing! Reach out for a hands-on demo showcasing test automation solutions supporting deep quality assurance across desktop, web and mobile apps leveraging real devices and browsers. The power of unit testing combined with functional testing awaits…
Sources:
[1] https://research.aimultiple.com/test-driven-development/
[2] https://leansoftwareengineering.com/ksse/test-driven-development/
[3] https://codingsans.com/blog/test-driven-development
