How to Build Right Testing Pyramid?

“The Right Testing Pyramid is a widely adopted concept in software testing methodologies; therefore, it guides teams in structuring their automated testing efforts efficiently.” 

While planning to build a product, we need to carefully balance the different components of the product whether its software, hardware or a combination of both. 

To create a successful and valuable product, you need to ensure several key aspects.

User Needs and Requirements, Quality, Reliability, User experience, Security, Privacy, Scalability, Compatibility, documentation, compliance etc. 

Quality and reliability are essential pillars for every product; therefore, whether it is software, hardware, or a blend of both, they remain crucial. They are indispensable in ensuring customer satisfaction and, therefore, in the creation of superior products.

The Right Testing Pyramid, therefore, acts as a mediator in achieving high quality and reliability in software development through its structured approach to testing at different levels.

The software development project begins with the use of Testing Pyramid concepts and, moreover, maintains them throughout its lifecycle.

How does the Right Testing Pyramid organize software testing into different layers?

Mike Cohn introduced the right testing pyramid as an analogy for structuring software testing; Consequently, it has become widely adopted in engineering circles and remains the industry standard. The right testing pyramid conceptually organizes testing into three layers.

At the bottom of the pyramid are unit tests. These tests check small parts of the code like functions or classes to make sure they work correctly. Unit tests run the code directly and check the results without needing other parts of the software or the user interface; therefore, they are more isolated and efficient.

Moving up one level from unit tests, we have integration tests (or service tests). These tests check how different parts of the system work together, like making sure a database interacts correctly with a model, or a method retrieves data from an API. They don’t need to use the user interface; instead, they interact directly with the code’s interfaces. 

At the top of the pyramid are end-to-end tests (E2E), also known as UI tests. These tests simulate real user interactions with the application to ensure its functionality. Unlike a human conducting manual testing, E2E tests automate the process entirely. They can click buttons, input data, and verify the UI responses to ensure everything functions correctly. 

As you can observe, the three types of tests vary significantly in their scopes: 

1. Unit tests are quick and efficient, pinpointing logic errors at the basic code level. They demand minimal resources to execute. 
2. Integration tests validate the collaboration between services, databases, and your code. They detect issues where different components meet. 
3. E2E tests require the entire application to function. They are thorough and demand substantial computing power and time to complete. 

Why We Should Use Testing Pyramid?

The characteristics of each test type determine the shape of the pyramid.

Unit tests are small-scale and straightforward to create and manage. Due to their focused scope on specific code segments, we typically require numerous unit tests. Fortunately, their lightweight nature allows us to execute thousands of them within a few seconds. 

End-to-end (E2E) tests are more challenging to create and maintain, use a lot of resources, and take longer to run. They validate a wide range of application functions with just a few tests, so they need fewer tests overall.

In the middle of the testing pyramid, integration tests are comparable in complexity to unit tests. However, we require fewer integration tests because they focus on testing the interfaces between components in the application. Integration tests demand more resources to execute compared to unit tests but are still manageable in terms of scale. 

Do you understand why the pyramid has its shape? Each layer represents the recommended amount of different types of tests: a few end-to-end tests, some integration tests, and lots of unit tests.

As you move up the pyramid, tests become more complex and cover more of the code. This means they take more effort to create, run, and maintain. The testing pyramid helps balance this effort by maximizing bug detection with the least amount of work. 

The Testing Pyramid shape often naturally appears in software development and testing for several reasons: 

1. Progressive Testing Needs: Initially, developers focus on unit tests because they are quick to write and provide immediate feedback on individual code units. As the project progresses and we integrate more components, we naturally need integration tests to ensure these components work together correctly. 

2. Development Lifecycle: At the outset of a project, there’s typically a focus on building core functionalities and prototypes. End-to-end tests, which require a functional application, are challenging to implement early on. Developers prioritize unit and integration tests during this phase to validate foundational code and ensure basic functionality. 

3. Developers can run unit tests frequently during development because they are lightweight and execute quickly. Integration tests require more resources but are still feasible as the project advances. We defer end-to-end tests until later stages when the application matures due to their complexity and dependency on a functional UI.

4. Adoption of Testing Frameworks: Frameworks like Behavior-Driven Development (BDD) encourage writing acceptance tests (including E2E tests) from the project’s outset. When teams adopt such frameworks, they are more likely to incorporate end-to-end testing earlier in the development process. 

In essence, the pyramid shape reflects a natural progression in testing strategies based on the evolution of the software from its initial stages to more mature phases. Developers and testers typically begin with unit tests, add integration tests as they build components, and implement end-to-end tests once the basic functionality stabilizes.

Another factor influencing the pyramid is test speed.

Developers run faster tests more frequently, providing crucial feedback quickly for productive development. 

Tests at the bottom of the pyramid are quick to run, so developers write many of them. Fewer end-to-end tests are used because they are slower. For example, a large web app might have thousands of unit tests, hundreds of integration tests, and only a few dozen end-to-end tests. 

Test Type	Order of Magnitude
Unit Test	0.01 – 0.0001 s
Integration	1 s
E2E Test	10 s

Realtime Usage in Industry – 

1. Unit Tests (Bottom of the Pyramid): 
   • Purpose: Unit tests are the foundation of the pyramid, representing the largest number of tests at the lowest level of the application.
   • Scope: They validate the functionality of individual components or modules in isolation. 
   • Characteristics: Unit tests are typically fast to execute, isolated from external dependencies, and provide quick feedback on code correctness. 
   • Tools: Automated unit testing frameworks such as JUnit, NUnit, and XCTest are commonly used for this layer. 

2. Service/API Tests (Middle of the Pyramid): 
   • Purpose: Service tests validate interactions between various components or services within the application. 
   • Scope: They ensure that APIs and services behave correctly according to their specifications. 
   • Characteristics: Service tests may involve integration with external dependencies (like databases or third-party services) and focus on broader functionality than unit tests. 
   • Tools: Tools like Postman, RestAssured, and SoapUI are often used for automating service/API tests. 

3. UI Tests (Top of the Pyramid): 
   • Purpose: UI tests validate the end-to-end behavior of the application through its user interface. 
   • Scope: They simulate user interactions with the application, checking workflows, navigation, and overall user experience. 
   • Characteristics: UI tests are typically slower and more fragile compared to lower-level tests due to their dependence on UI elements and changes in layout. 
   • Tools: Selenium WebDriver, Cypress.io, and TestCafe are examples of tools used for automating UI tests 

Conclusion

The Right Testing Pyramid is a strategic model that emphasizes a balanced and structured approach to testing. It helps teams achieve efficient and effective quality assurance by prioritizing a higher number of unit tests, a moderate number of integration tests, and a focused set of end-to-end tests. This approach not only optimizes testing efforts but also supports rapid development cycles and ensures robust software quality. Some key principles of right test pyramid concluded here : 

• Automation Coverage: The pyramid emphasizes a higher proportion of tests at the lower levels (unit and service/API tests) compared to UI tests. This optimizes test execution time and maintenance efforts. 
• Speed and Reliability: Tests at the lower levels are faster to execute and more reliable, providing quicker feedback to developers on code changes. 
• Isolation of Concerns: Each layer focuses on testing specific aspects of the application, promoting better isolation of concerns and improving test maintainability. 
• By following the Test Automation Pyramid, teams can achieve a balanced automation strategy that maximizes test coverage, minimizes maintenance overhead, and enhances the overall quality of their software products. 

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