Types of Software Testing: Unit Testing vs. Integration Testing vs. End to End Testing (e2e)

In the world of software development, guaranteeing the quality and functionality of the product it’s of vital importance.

This is revealed by a recent report in which it is estimated that software defects cost companies around $1.7 trillion dollars in losses each year.

Having a robust testing approach to avoid expensive problems and delivering high-quality software is therefore critical to any project.

Throughout this article we’ll examine the key differences, benefits, and use cases of each test type, so you can make informed and efficient decisions when implementing your testing strategies.

Index

• Meaning and scope of unit testing
• What are end-to-end tests and how do they differ from other types of tests?
• Definition and purpose of integration tests
• Comparison and selection of the types of software tests: Unit Test, Integration Test and end-to-end Test (e2e)
• Yeeply IT teams apply all types of software testing for better software testing

Meaning and scope of unit tests

Unit tests are positioned as the first line of defense in the error detection within software development.

Designed to be implemented locally, these tests are responsible for validating the most elementary components of the logic of your code.

Whether it’s a function, class, or any other code entity, unit testing is meant to test every feature and possible logical path.

In the ideal of 100% code coverage, a unit test would be written for every possible flow in the code. In practice, good code coverage is closer to 80%.

The breadth of coverage gives you an extra level of confidence in your code, because once your unit tests pass, you can trust the robustness of your software.

 

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Advantages and benefits of unit testing in software development

• First line of defense against errors: Unit testing is the first line of defense against bugs in your code. They are designed to run locally and check the most fundamental aspects of your code logic.
• Code coverage: Unit tests are designed to test every feature and potential logical path. Writing a unit test for every possible flow of your code is called “100% code coverage”. Although around 80% code coverage is considered a good percentage, the more coverage you have, the more confident you can be in your code.​.
• Early bug detection: Unit tests are a low-risk way to quickly detect bugs. They should always be used, regardless of whether you are writing code for a small project or deploying to billions of users.

What are end-to-end tests and how do they differ from other types of tests?

End-to-end or E2E tests are a form of software testing that seeks to ensure workflows work from start to finish, just as an end user would experience it.

Unlike unit and integrated tests, end-to-end tests seek to test the product in the same way that a real user would experience it, validating different subsystems and layers of the application.

Unit tests, on the other hand, are your first line of defense against bugs.

These tests are intended to check the most fundamental parts of your code logic, such as a function or a class. The idea is to test every possible feature or logical path in the code.

For its part, integration testing typically involves testing for specific functionality that has dependencies on other functionality, such as a function calling another function.

These tests seek to verify the connectivity and the communication between the different components of the application.

How manual end-to-end tests differ from automated end-to-end tests

End-to-End tests, both manual and automated, play a crucial role in software quality assurance, allowing the functionality and performance of the entire system to be validated.

Although both tests pursue the same goal, there are notable differences between them in terms of implementation, effectiveness, costs, and required resources.

Manual End-to-End testing is performed by a quality team or tester, who simulates end user behavior and verifies that the system works as expected.

These allow you to identify usability and user experience issues that might go unnoticed in an automated test. However, manual testing can be slower, more expensive, and more prone to human error.

On the other hand, automated End-to-End tests use scripts and software tools to execute tests on a scheduled basis.

These are often faster, more efficient, and more consistent than manual tests, since they can be run repeatedly without human intervention.

Automated tests are especially useful for repetitive tasks and for validating functionalities that have already been manually tested.

That being said, creating automated test scripts can require a significant upfront investment in terms of time and resources.

Advantages and challenges of end-to-end tests in software development projects

Some of the major benefits and challenges of E2E testing are:

Advantages of end to end tests

• Complete test coverage: Thetest E2E they focus on simulating the end user experience, which allows verifying that all system components work in an integrated manner.
• Detection of complex errors: By simulating real workflows, E2E testing can help identify and fix complex problems that may not be detected at other test levels.
• Improved confidence in software: I e2e test they can increase confidence in the software, since they allow you to verify that the entire system works correctly before it is released.

End to End test challenges

• Implementation complexity: Since E2E testing involves testing the entire system, it can be more complex and expensive to implement compared to unit or integration tests.
• Execution time: E2E tests typically take longer to run than other types of tests, which can increase overall development time.
• False positives: Sometimes E2E tests can generate false positives due to temporary or test environment-specific issues. This can translate into time spent investigating “problems” that are not actual bugs in the software.

 

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Definition and purpose of integration tests

Integration tests are a crucial part of the software development process.

Unlike unit tests, which focus on verifying the functionality of individual components of a system, integration tests are concerned with testing how different parts of a system interact with each other.

These are carried out in functionalities or modules that depend on other functionalities, such as a function that calls another function. The main purpose of these tests is to check the connectivity and communication between different components of the application.

There are three main reasons for performing integration tests:

Ensure synchronization between modules when they work together to carry out a specific task, since these modules could have been developed by different teams or developers.

Help validate application interfaces to ensure that data flowing from one module to another is appropriate.

Verify that connectivity between modules works as originally conceived.

Importance of integration tests in the development process

Integration tests allow to detect errors that can arise when different components or modules of the system interact with each other. We are talking, then, about errors that could not be detected by unit tests.

Furthermore, since different modules can be developed by different teams, integration testing is essential to ensure that all modules work harmoniously once integrated.

This helps to maintain the quality of the software and to reduce the time and resources required to troubleshoot that arise due to faulty integration.

Finally, integration tests can also help validate application interfaces and ensure that data flows correctly from one module to another, which is crucial for the proper functioning of the system.

Comparison and selection of the types of software tests: Unit Test, Integration Test and end-to-end Test (e2e)

The three main types of software testing are unit tests, integration tests, and end-to-end tests. Let’s see its main characteristics and differences:

Unit Testing

Unit testing is, as we have been pointing out, the first level of defense against errors.

These are designed to run locally and they check the most fundamental bits of logic in your code, such as individual functions or classes.

Unit tests aim to test each feature/potential logical path. The greater the coverage, the greater the confidence in the code.

Integration test

Unlike unit tests, which test a small isolated unit, integration tests generally involve testing a particular functionality, known as a module, that has dependencies on other functionality (for example, a function that calls another function).

The objectives of these tests are to verify the connectivity and communication between different components of the application, ensure synchronization between modules when they work together to perform a specific task and validate application interfaces so that the data that flows from one module to another is appropriate.

Test End-to-End (e2e)

End-to-end testing seeks to test the product in the same way that a real user experiences it.

They want to make sure everything works as expected (functionality and performance).

The two main goals of end-to-end testing are simulate the step-by-step experience of a user and allow you to validate different subsystems and layers of the application​​.

 

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Key differences between unit tests, integration tests and end-to-end tests

Unit tests are atomic tests that are performed within the scope of a single component or action. They do not go beyond the scope of this atomic component.

For example, unit testing does not involve the joint testing of various components such as reducer && saga or component && action && reducer && saga​.

On the other hand, integration tests are an extension of unit testing and consist of the integration of multiple components.

An example of an integration test could be the following flow: a component clicks a button -> this launches an action -> which is monitored by a saga -> which calls a (mock) API endpoint -> which modifies the reducer state -> which in turn changes something in the same or another component​.

Finally, end-to-end (E2E) tests are used to test the final results, such as the interaction of an external user with our system or user interface.

Unlike unit and integrated tests, which focus on individual components or the interaction between them,E2E tests evaluate the functionality of an application as a whole from the point of view of the end user.

Considerations for choosing the most appropriate type of test according to the context

The choice of the most suitable type of test depends on the specific context and the objectives of the test. That being said, I give you a general guide to help you decide between unit, integration and end-to-end (E2E) tests:

Unit tests

Unit tests are essential to verify the fundamental logic of your code.

You should always use them, regardless of whether you are writing code for the school or deploying code to thousands of users.

These tests are a low-risk way to quickly catch bugs.

If you are working on a functionality that can be tested in isolation and your goal is to ensure that each individual function, class, or logic works as expected, unit testing would be the appropriate choice.

Integration testing

Integration testing is useful when you need to verify connectivity and communication between different application components.

If you are testing a feature that has dependencies on another feature, such as a function calling another function, integration tests would be appropriate.

For example, if you are testing a flow that involves a component that launches an action, that is watched by a saga, that calls a (mock) API endpoint, modifies the state of the reducer, and changes something in it or another component, you should consider integration testing.

Pruebas End-to-End (E2E)

E2E tests are useful when you need to validate the functionality and performance of the application in a scenario that simulates the end user experience.

These tests involve verifying that the entire system works correctly together, from user interface interactions to the database.

If you are interested in testing the product in the same way that a real user would experience it, E2E testing would be the right choice.

 

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Yeeply IT teams apply all types of software testing for better software testing

At Yeeply we know the importance of thorough and rigorous testing to ensure the quality and performance of our software.

By applying all these types of tests, we make sure that we detect and correct any problems or errors in the software before it is delivered to our customers.

Our goal is to offer high-quality products that meet the expectations of our users and provide an exceptional experience.

At Yeeply we are committed to continuous improvement and excellence in software development: trust our IT teams to ensure better software testing and have quality products that boost your success in the digital world.

Our IT equipment is dedicated to applying all types of software tests, including unit tests, integration tests, and end-to-end tests. Hire freelance programmers for complete and effective testing.

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