What is End to End Testing?

End to end testing is an important technique used to validate the flow of an application from start to finish. The main objective of this testing is to simulate user behavior and thoroughly test components to identify any integration issues. In more precise terms, end to end (or E2E) testing is a methodology in which testing takes place from the very first point of contact with the application to the end result, to check the quality of the functionalities and communication with external interfaces such as databases, network, and other applications.

End to End Testing

Why End to End Testing is Needed

Applications being developed today are increasingly complex because they are designed to integrate with various external systems. Therefore, due to the interconnectedness of multiple subsystems, the application needs to be tested from every point. If any subsystem fails or is unable to perform the intended operation, then potentially, the whole system could be heading towards failure and loss of business. Some reasons to perform end-to-end testing are as follows:

  • E2E testing makes it possible for us to identify issues at the backend and database layer, which is the core part of the application.
  • Front end issues can be identified to make sure the user experience is consistent throughout the application and across various environments and platforms.
  • Performing E2E testing can give extra confidence to the tester because test case coverage is increased.
  • E2E testing helps in identifying problems where multiple components are interconnected, and the risk potential is higher.

How does E2E Testing Work?

Every enterprise application has complexity at various levels. Take an example of a website which has sales, when things are brought or sold, a certain percentage amount is paid as government taxes and other things. There are also regulatory requirements that are in place to manage such scenarios, and they are all reflecting and managing in the application. With this example, and keeping in mind E2E testing process, multiple transaction levels are involved, which make it difficult to test the application. Hence, thorough end-to-end testing is necessary to manage risk and avoid breakage.

How to Perform End to End Testing?

Below are some guidelines for the testing team before proceeding with end-to-end testing.

  • Analyze and understand the complexity of the requirements
  • Properly set up the testing environment for smooth deployment and delivery of the application
  • Analyze the performance criteria of the application
  • Assess the risk factors of the main system along with the integrated subsystems
  • Prepare a proper test strategy for E2E testing
  • Design test cases and track the coverage from Requirement Traceability Matrix
  • Maintain test data properly for the purpose of reuse

End-to-End Testing Parameters

Preparation of Test Cases (current vs. planned):

The team can check the current status of their test cases against the those they have planned through a graph. The graphical representation will give a clear representation of the progress made.

Weekly Test Progress:

Progress can be measured by creating weekly test reports, with percentage scores representing tests executed, not executed, passed and failed test cases, and then compared with the previous week’s progress report.

Defect Report:

The team should prepare the defect report on the basis of severity and priority to reflect the execution status of test cases. Later the percentage of open and closed defects can then be compared with the previous week’s result so progress can be measured.

End to End Testing Environment:

The testing environment is where we track the time allocated for testing, versus the actual time spent on performing end-to-end testing.

Methods used in E2E Testing

  • Horizontal: With this method, the tester confirms the flow and behavior of the application to learn if the user can navigate across the system without any glitches or defects.
  • Vertical: With this method, the tester verifies the applications thoroughly in a sequential manner from one layer to another layer (database, API, and frontend). This method is complicated compared to the horizontal method and requires more technical knowledge where we employ a combination of both black box and white box testing.

How End to End Testing differs from System Testing

The aim of system testing is to verify the behavior of the whole integrated system, with focus on the external working of the application (more specifically, black box testing is performed) from the user’s perspective by imitating real-world environment whereas end to end testing aims at verifying the system as well as the integrated sub-system(s). Some differences are as follows:

  • In system testing, we emphasize testing the system’s functionalities according to the written specifications. In E2E testing, all layers are taken into consideration (backend, frontend, interfaces, etc.)
  • System testing is executed once all the modules have been integrated, while E2E testing is performed once system testing has been completed.
  • For system testing, we can use both manual and automation approaches, but the manual approach is preferable and recommended for E2E testing because the automation approach is more time-consuming and can be costly for the organization.


End to end testing plays an especially important role for applications where sub-systems are interconnected, and risk is potentially higher. E2E testing imitates the real environment where testers identify defects at all use levels.