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testing pyramid
7th March 2022

The Testing Pyramid and How to Use It

The testing pyramid is a concept that categorizes software tests into three groups. It helps the development team and QA professionals to achieve effective software testing and high-quality software. It should form part of your core business logic. Without using the testing pyramid, software developers could waste time and testing efforts on time-consuming tasks that they can complete more efficiently and faster.

Let's explore the traditional software testing model and its challenges. And let's see how the testing pyramid can help Agile teams to build a more reliable test suite and improve test coverage while saving time.

Why Efficient Agile Teams Need the Testing Pyramid

One of the most common challenges for a test-driven development team is waiting for their test suite to run during the testing process. What typically happens during functional testing is that Agile teams rerun the test suite repeatedly after tests fail.

Many development teams believe that if they keep running test scripts, it will magically fix the problems. If this is what your development team is doing, there's a pretty good chance their test suite does not follow the test automation pyramid.

All software developers and QA professionals should know the test automation pyramid. It is an essential framework that can help any development team produce high-quality software. It helps them figure out if they introduced any bugs into the application with an update, developing a more reliable test suite.

Not to mention how much testing time it shaves off the process. Before we dive into the test automation pyramid and strategies for managing it, let's start at the beginning: the definition of test automation.

software testing pyramid

Test Automation 101

Test automation is a practice used by developers and testers that involves running tests and test scripts automatically, managing the test data, and using these results to improve software quality. Various testing types can be automated, including unit testing, UI widgets testing, smoke tests, integration testing, regression tests, cross-browser testing, and UI tests.

QA teams can use a generic open-source framework like Robot Framework to create automated tests. User interface testing, and UI widget testing, can be done significantly faster with test automation, but other test types depend on manual testing.

For test types like exploratory tests, you'll need manual testing. It's not possible to automate exploratory tests. Unlike UI testing, exploratory testing relies on the tester thinking outside the box to come up with use cases that a test case may not cover.

For example, the tester may run a test and then adapt it to see if they could develop new results. User interface tests have clearly defined steps because the software is designed to be used in a specific way with unique parameters. There are only so many visual elements part of the user interface that users will come into contact with.

Why test automation is crucial

Testing takes time and effort. Even something as simple as testing a humble dialog box pattern requires planning and step-by-step execution of the plan. For the sake of using time effectively, test automation is an integral part of traditional testing. It can drastically reduce testing time because the environment is prepared and cleaned up automatically.

The Agile test automation pyramid is also helpful for future insights; the test run results can help developers identify and debug problems faster. Now that we're covered test automation let's take a closer look at the Agile test automation pyramid.

What is the Test Automation Pyramid?

The Agile test automation pyramid represents the different types of tests and how often they should feature in the test suite. It is an essential element of test design and is an excellent way to give developers immediate feedback to avoid code changes from breaking existing features. A testing pyramid has three sections:

  1. Unit tests - at the lowest level
  2. Integration tests - in the middle
  3. End-to-end tests - at the top

Let's delve a little deeper into the three tiers to see why we need to distinguish between the types of tests in the test suite.

agile testing pyramid

Unit Tests

A pyramid needs a robust base, and that is exactly what unit tests are there for. Unit testing is the most common type of test required to create an effective testing pyramid.

What are unit tests?

Unit tests focus on testing a small piece of functionality or component of the code. The goal of a unit test is to validate that the particular unit is behaving as expected when placed in isolated conditions. A unit test could target a class or an individual function. Developers should focus on testing several scenarios that cover all scenarios.

For example, to test a happy path using a well-defined test case with known input to execute the test without exception and produce the expected output. Or error handling to check whether the software can handle the errors that could happen in the future.

Mocking frameworks in the unit testing pyramid

Mocking frameworks like JavaScript's Sinon or Java's Mockito are tools that are typically found in the unit test tier. They are used to generate replacement objects such as Stubs and Mocks. Stubs are objects that return specific results during testing based on specific inputs and won't respond to anything outside of this.

Mocks are more sophisticated, programmable versions of Stubs. It makes it easier for developers to control how components used during testing behave. By isolating dependencies, mocking frameworks improve test speeds and aid developers in writing more concise and focused unit tests.

testing

Speed is essential in unit testing

The unit test suite should run relatively quickly because it's the most extensive set of tests in the testing pyramid and will keep growing as developers add new features to the software. Every time a developer changes the code, they should run the unit test suite to get immediate feedback on whether or not the new code broke anything in the codebase.

If the unit test suite is fast, developers will be encouraged to run it more often. The more frequently unit tests are run, the less time they will spend on debugging problems in the future.

Don't forget about TTD!

Your best bet to build a robust unit test suite is practicing test-driven development (TDD). TDD requires a test to be written before any code, so you create new unit tests every time you add a new feature. Although unit tests don't represent a fully deployed application, they are excellent for testing smaller parts of the codebase.

Unit tests don't comprehensively cover user interface testing and don't test how the application will interact with the outside world. For that, you'll need the next tier of the Agile pyramid: integration tests.

test pyramid model

Integration Tests

Unit tests are an essential part of the testing pyramid, as we saw above. But, they're not enough to ensure a quality codebase and Agile success. Integration tests are the next step to take. Integration tests should not appear as often as unit tests because they make up the middle tier of the test automation pyramid.

It's also important to note that integration testing can cause some level of confusion in the development world, so let's first explore exactly what it entails.

What are integration tests?

We can define integration tests as tests that look at the codebase and its interactions with external components. There are various external components that applications depend on, for example, databases.

Since databases are some of the most common and crucial components required by software applications, it's vital to test that the application interacts with the databases as needed. Before you begin testing this type of integration, it's essential to ensure that the test database is as similar as possible to the database in the production environment.

test automation

Testing integration with external services

Another part of integration testing is to test the integration with external services like APIs. These integration tests are called service tests and should cover how the code interacts with every external service.

You may be wondering why developers bother with unit tests when all they need are integration tests to see if the code is functioning with external dependencies? This is because those dependencies are outside the application, so comprehensive testing requires communication between the application and the external service.

This communication will make a call to the web service or database, which means that the integration test won't run quite as quickly as unit tests. Furthermore, when running an integration test with an external web service, you have to create a preproduction environment as similar as possible to the production environment for testing against.

Finally, it could be challenging to test every scenario from an integration point of view because it is impossible to control the response from the external dependency, for example, when the external service generates an error case.

software development

End-to-End Tests

The top tier of the test automation period is ensuring that the application is working as intended, from start to finish. End-to-end tests are the final step and the top of the test automation pyramid.

What are end-to-end tests?

These tests are exactly what it says. They are created to test that every part of the application is working correctly, i.e., that the integration between the front end and the back end functions as it should.

How to approach end-to-end tests

The best way to approach end-to-end tests is to look at them from an end user's perspective. How would somebody interact with the application? What would they do to achieve their goals with it, and what can go wrong? The idea is to write a test based on these actions. For example, to test if the login page works, the following steps may be needed:

  1. Locate the username text field and enter the username into it.
  2. Locate the password text field and enter the password into it.
  3. Find the Submit button and click it.

Why are end-to-end tests at the top of the test pyramid?

End-to-end tests are the top tier of the test automation pyramid because it is potentially the most time-consuming part of the test process. They also tend to be fragile, and, like integration tests, end-to-end tests may have unreliable external dependencies.

agile team

Every Codebase Should Have a Strong Testing Pyramid

Now that we've defined the test pyramid, it's clear that a well-designed test suite and accurate test data are not enough to ensure successful testing efforts. The testing pyramid is crucial for success. When a development team has a robust testing pyramid and test automation, it will help them to release features quicker and improve quality.

Conclusion

The test automation pyramid is a framework that defines three testing types and how many times they should appear during a test project.

The base of the testing pyramid is made up of unit tests. You should run them frequently and quickly. The middle tier of the testing pyramid is where you'll find integration tests. They focus on how your code interacts with the world outside with external services.

At the top of the test pyramid, you'll find end-to-end tests. They are written from the user's perspective and are there to test the entire application's functionality, from the front end to the back end.

Just as in iterative development, you should break the testing process into smaller parts for improved efficiency. Working with the project management team, the testing team, and the software application developers should write tests based on the test automation pyramid. Agile testing relies on this concept for all aspects of testing, including UI testing, unit tests, integration testing, and cross-browser testing.

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Article written by Duncan Brigginshaw
Co-Founder and Technical Director

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