17 minutes to read
5 differences between integration testing and end-to-end testing
Mykhailo Ralduhin
Senior QA Engineer
Are you ready to lose $440 million quickly due to software failure, or face $30 billion in damages and fines because you skipped testing? Software powers our world, but even the smallest mistake can cause huge problems. Think about Sony's PlayStation Network. Hackers broke in and stole personal information from 77 million users. The problem was a common software flaw that good testing could have stopped. This cost Sony a lot of money and hurt their reputation.
Now, picture Knight Capital Group, a company that lost $440 million in just 45 minutes because of a simple software error. If they'd tested the software properly, they could have prevented it.
If after all this information your answer is “No”, then it is time for you to discover integrated and end-to-end testing – two approaches that can ensure that your software is 100% secure and flawless.
In this article, we'll delve into the five key differences between integration testing and end-to-end testing and explore how these two testing strategies work together to ensure software reliability, drive customer loyalty, and stay ahead in the competitive market.
End-to-end testing vs integration testing: understanding the basics
Before you start your next big software project, it's important to understand the basics. Let's look at the key differences between end-to-end testing vs integration testing, so you can make smart decisions for your company.
What is integration testing?
Integration testing is the detective work that happens when you put all the pieces of your software puzzle together. Its main goal is to ensure the individual components play nicely with each other. It's all about checking if the different parts "speak the same language" and share information smoothly. If integration testing is skipped, you risk unexpected errors or even the whole system crashing. Essentially, it's like verifying that the connectors between different software modules function as they should. Integration testing:
Catches compatibility issues early on, minimizing the chance of major problems down the line.
Ensures that all components work harmoniously, leading to a more stable and reliable application.
Provides confidence that the software meets requirements and functions as expected.
Finds and fixes integration issues before they escalate into costly fixes or project delays.
Usually, integration testing happens after each part (or "unit") has been tested separately. You want to make sure each piece works before you try to combine them. Integration Testing fits right after unit testing, the testing of individual parts. To do that, testers (or developers) create special tests to check these connections. They might send data from one part of the software to another and see if it gets the right response. They check the integration testing framework. Not only that, but they will test the interface between the two systems.
For example, you are developing a mobile app that is designed to send messages. Unit tests check that the “message composing” part works. Integration tests сheck how the message composing part connects to the “sending” part. To perform integration testing, QA testers can use various tools and techniques, such as:
Top-down approach: Testing begins with the main module and progressively integrates lower-level modules, simulating the user's perspective.
Bottom-up approach: Testing starts with the lowest-level modules and gradually integrates them with higher-level modules. This is helpful when core modules are ready before the user interface.
Big bang approach: All components are integrated and tested at once. This approach is suitable for smaller projects. However, it is difficult to isolate the cause of the errors if something goes wrong.
What is end-to-end testing?
End-to-end testing is like taking your software on a complete journey, from the very first step a user might take to the final outcome. Think of it as checking the entire chain of events in your application, ensuring everything connects and works smoothly, just like a fully automated process.
This type of testing is crucial because it validates the system's behavior from the user's perspective, ensuring that the application behaves as expected. E2E testing verifies that the entire workflow is correct, including all interactions between different components, systems, and databases. E2E testing plays a vital role in software development, as it helps to:
Catch system-wide issues early: E2E testing detects system-wide issues, such as bugs, errors, or performance issues, early on before they affect the end product. This makes the software robust and business-ready.
Decrease development time and expense: E2E testing decreases development time and expense with rework, bug fixing, and maintenance.
Improve user experience: E2E testing helps ensure that the application is user-friendly, simple to use, and provides a seamless experience, leading to higher user satisfaction and loyalty.
Compliance and quality assurance: end-to-end testing ensures the application is in accordance with all the industry standards, and quality compliant, reducing the risk of non-compliance and reputation loss.
E2E testing is typically performed after integration testing and before user acceptance testing (UAT). This allows developers to validate the system's behavior and ensure that all components work together correctly before the end-users test the application.
To perform end-to-end testing, QA testers can use various tools and techniques, such as:
Automation Tools like Selenium, Cypress, and Appium help automate E2E tests, making it easier to test complex workflows and reduce testing time.
Manual testing involves simulating user interactions and testing the system's behavior manually.
Test frameworks, such as Jest and Pytest, provide a structured approach to end-to-end testing, enabling you to write and execute tests more efficiently.
Key differences between integration testing and end-to-end testing
Objective
Verify interaction between modules/components.
Verify the entire system flow from start to finish.
Scope
Tests a subset of the system; focuses on interfaces.
Tests the complete system.
Focus
Module interfaces, data flow between modules.
User workflows, system functionality as a whole.
Testing level
Integration level (between units).
System level.
Environment
May use stubs/mocks to isolate modules.
Production-like or near-production environment.
Complexity
Generally less complex than E2E.
More complex, often involves multiple systems/modules.
Execution time
Can be quicker than E2E.
Can be longer, more time-consuming.
Defect detection
Focuses on identifying integration issues.
Focuses on system-level issues, user experience problems.
Automation
Can be automated, often requires more manual effort.
Heavily automated, relies on test automation frameworks.
When to use
After unit testing, before E2E.
After integration testing (or as a complement).
Team skills needed
Understanding of module interactions and APIs.
Expertise in test automation, system knowledge, user flows.
Integration testing and end-to-end testing are both critical parts of the testing process, but they are fundamentally different in their approach and objectives.
Integration testing validates that different modules of a software system function correctly together, focusing on the interactions of the modules. This contrasts with the testing performed by End-to-end testing.
This testing involves a complete workflow in the entire system from start to finish, simulating the real-world use scenario. It also checks the entire workflow for interactions across all the components of a system.
Testing scope and objectives
The primary difference between integration testing and end-to-end testing lies in their focus. Integration testing zeroes in on component interactions, while end-to-end testing validates complete user workflows.
Integration testing is about ensuring that individual software modules or components can exchange information and work together effectively. For example, a website has a "Login" module and a "Profile" module. An integration test might verify that after a user successfully logs in, the system correctly displays their profile information. Testing the data and information between the components in this integration test. The goal is to verify that the parts play nice together. It does not test every aspect of the entire system.
E2E testing goes much broader, encompassing the entire process a user goes through. You're verifying that all systems, including the user interface, backend databases, and even external services (like payment processors), all work together seamlessly to provide the user with a complete and functional experience. This includes system testing as it tests an entire system in its entirety.
In a nutshell:
Integration testing: Focuses on the "how" the software's pieces fit together and communicate.
End-to-end testing: Focuses on the "what" the system does as a whole for the end user.
Speed and complexity
When it comes to speed and complexity, there are notable differences between integration testing and end-to-end testing.
Integration tests are typically faster to execute because they focus on specific components or modules within the system. You can expect to dedicate just 90 seconds per test or about less than 1 hour for 200 tests in a batch. Integrated tests don't require the entire system to be set up and running, these tests can be run in isolation, which reduces the overall execution time. Additionally, integration tests usually require less complex setup and configuration, as they only need to simulate the interactions between the specific components being tested.
In contrast, end-to-end tests are generally slower to execute and more complex to set up. They may take up to 4 - 8 hours. This is because they involve testing the entire system, from start to finish, which requires a more comprehensive setup and configuration. E2E tests often need to simulate real-world scenarios, which can involve multiple components, systems, and even external services, making them more time-consuming and complex to execute.
The difference in execution time and complexity between integration testing and E2E testing has significant implications for the testing process. Faster execution times and simpler setup for integration tests make them ideal for:
Continuous Integration/Continuous Deployment (CI/CD) pipelines: Integration tests can be run quickly and frequently, providing rapid feedback on code changes.
Developer workflows: Faster execution times enable developers to quickly test and iterate on their code, reducing the overall development time.
On the other hand, end-to-end tests are better suited for:
Regression testing: E2E tests can help ensure that changes to the system haven't introduced new bugs or broken existing functionality.
User acceptance testing (UAT): end-to-end tests can simulate real-world scenarios, providing confidence that the system meets the required standards of quality and functionality.
Automation and tooling
Integration testing focuses on component-level interactions, while E2E testing centers on the entire user experience. Their automation and tooling needs differ.
Integration testing relies on unit testing frameworks like JUnit (Java) or pytest (Python). Testing modules individually is useful for isolating components and verifying their correct interaction. Test doubles are heavily used; mocking and stubbing are key techniques. These allow you to simulate dependencies, helping to test isolated components.
E2E testing uses UI-based automation and business process testing, with user scenarios and API testing. Frameworks like Selenium, Cypress, or Playwright automate browser interactions. Behavior-Driven Development (BDD) is common using frameworks like Cucumber. This involves writing tests based on user stories and business requirements.
Cost and resource allocation
On average, nearly a quarter of the yearly IT budget, specifically 23%, is dedicated to quality assurance and testing, according to a panel of CIOs and tech leaders. The financial and resource commitments for integration and end-to-end testing strategies diverge significantly, mirroring their distinct scopes and objectives. Understanding these differences is crucial for informed decision-making during project planning and budgeting.
Cost
$80,000 - $200,000+ (can be higher for very complex systems).
$40,000 - $100,000+ (varies with the number of modules).
- Testers
5-10+ experienced testers, potentially with domain knowledge.
3-6 testers, some can be junior-level.
- Test Data
Large, realistic test data sets.
Smaller, focused test data.
- Test Environment
Production-like, often requiring dedicated servers/instances.
May be a test environment with stubs/mocks.
- Test Automation Tools
Sophisticated automation tools (e.g., Selenium, Cypress).
Automation tools, potentially with some custom scripting.
Integration testing, focusing on the interaction of individual software components, tends to be relatively more cost-effective. The primary driver of cost is the effort required to design, implement, and subsequently maintain the test suites. This encompasses the time investment of skilled testers and developers.
The complexity of the application's architecture directly influences the cost, as more intricate component interactions necessitate more elaborate test cases. Moreover, selecting and integrating the appropriate testing frameworks (such as JUnit, pytest, or similar tools), while beneficial, also carries an initial setup cost. The resources required are primarily human, involving the developers and testers dedicated to writing, executing, and analyzing the tests.
Automated testing tools and testing frameworks require a significant amount of processing power for execution, but the computing cost is typically modest in this context. The frequency with which integration tests can be run, and the resources required, are low, allowing it to be run more often.
E2E testing, designed to mimic the user's experience across the entire application, represents a more substantial investment. The cost implications are considerably higher, primarily driven by the complexity and scope of these tests. Since these tests simulate real-world scenarios, they often involve automated UI interactions, data setup, and backend processes, all of which consume significant time and resources.
The human element of testing is critical, and this cost may require a larger team with diverse skill sets to perform the necessary tasks. Furthermore, the cost of maintaining these tests can be substantial, as any changes to the user interface, business logic, or system dependencies necessitate updates to the test scripts. The duration of E2E tests can be extensive, especially for large applications with complex workflows, and the environmental setup (e.g., emulating network conditions, handling data dependencies) can be complex. The frequency of end-to-end tests will be less than integration tests.
Integration testing offers a leaner, more focused approach, while E2E testing provides a comprehensive evaluation of the end-to-end user experience, at the cost of significant investment in time, resources, and financial outlay. Choosing the appropriate strategy, or a combination of both, is a crucial decision for project success.
When to choose integration testing vs. end-to-end testing?
Choosing between integration testing and end-to-end testing requires a nuanced understanding of your project's requirements and priorities. The choice significantly impacts cost, time, and resource allocation.
According to Statista, Integration testing was considered as the best testing approach by 63%, while integration testing – by 48% of respondents.
Scenarios where integration testing is preferable
Integration testing, which is conducted during the development phase of the SDLC, soon after components are integrated, helps to identify and resolve issues arising during the integration process. You should choose this approach for
Component-focused testing: Integration testing excels when the primary focus is on testing the interactions between individual software components.
Early stage testing: Integration testing is beneficial early in the development cycle, when you need to verify the interactions of different modules or components.
API and microservices: For applications built on APIs and microservices, integration tests can be extremely useful.
Cases where end-to-end testing is necessary
E2E testing, on the other hand, is typically performed during the testing phase of the SDLC to validate the app's behavior in real-world scenarios and confirm that it meets functional and non-functional requirements. You can use it when you need:
User experience focus: end-to-end testing is crucial when you need to validate the entire system from the user's perspective.
Complex workflows: end-to-end tests are the most comprehensive when you have complex workflows.
User acceptance testing: end-to-end testing provides the basis for user acceptance testing (UAT) to simulate the production environment.
Release validation: end-to-end testing is used to validate that all the components are working correctly together.
How integration and end-to-end testing work together
How integration and end-to-end testing work together
Integration testing is often a precursor to E2E testing, helping to catch integration bugs.
E2E testing uses results from integration testing, ensuring system integration works seamlessly.
Key benefits
Isolates module-specific issues, helps identify defects.
Validates user experience, ensures system flows correctly.
Challenges
Can be time-consuming and resource-intensive.
Requires sophisticated test automation and realistic test data.
Relationship
Integration testing is a stepping stone to E2E testing.
E2E testing relies on integration testing for system validation.
Both integration and E2E testing are vital for comprehensive software quality assurance. They serve different but complementary purposes, and together, they provide a more robust approach to testing. To be exact with the combination of end-to-end testing and integration testing frameworks, you can achieve:
Synergistic relationship: The integration testing helps you test each of the components individually, while E2E testing is a powerful technique for verifying the entire system.
Early detection: Integration tests can find problems between software components or units, and E2E can find system-level issues.
Reduce risk: By combining testing types, you can reduce the risk of releasing a low-quality product.
Effectively combining integration and end-to-end testing requires a strategic approach. Here are some best practices for maximizing the benefits of both:
Define a comprehensive testing strategy: Determine the breadth and depth of testing; identify critical features and functionalities and prioritize tests based on risk and impact.
Automate wherever possible: Automation is important for both approaches to reduce the cost of testing and is crucial for improving the efficiency of testing. Schedule tests for the continuous integration pipeline.
Establish clear communication: Promote communication between developers, testers, and stakeholders.
Maintain a balance: Maintain a balance between integration and E2E testing. Balance the scope of both testing methods.
Start with Integration: Establish a solid foundation of integration tests to ensure component-level correctness.
Strategic use of E2E: Use end-to-end tests to cover key user journeys and business-critical functionalities. Focus E2E on the overall system's health.
Test environment: Create test environments that resemble production. Integration tests should have high code coverage.
By implementing these best practices, you can effectively combine integration and E2E testing to create high-quality software.
Conclusion
Integration and end-to-end testing are both essential for ensuring comprehensive software quality assurance. They serve different but complementary purposes, and together, they provide a robust approach to testing.
While integration testing helps you test individual components, end-to-end testing verifies the entire system. To have a project that is thoroughly tested, you need to maintain a balance between integration and end-to-end testing, tailoring your approach to the specific needs of your project.
To ensure your software meets the highest standards, consider hiring a reliable software testing services company. Look to DeviQA to help you create a product with confidence.
