Difference between functional test and end-to-end test

Question

What is the difference between functional test and end-to-end test?

Techopedia says that end-to-end test is

a methodology used to test whethe

Answer 1

I think the definitions of functional and end to end testing could vary based on the context of your project. I have seen different people use these terms to describe different things. That being said, usually this is what the 2 terms mean-

Functional testing - This refers to testing the functionality of system based on the requirements. This usually focuses on different requirements of the system and ensure it is working properly. For example - Logging into an application - could be one requirement and then a person could test this functionality manually or in an automated way. Similarly, adding a product to the cart could be one functionality, then, able to make a payment to purchase a product could be a functionality.

End to end testing - This refers to testing the system based on end to end user flows, instead of testing the system has separate components like in unit testing or story level testing. For example - Logging into the application, then adding a product to the shopping cart, then going to the check out screen and then placing an order and then logging out of the application could be one user flow.

Answer 2

As I understand it, the biggest difference between the two is that an end-to-end test requires the test to setup the system components as they are in production. Real database, services, queues, etc. The reason for this is to see that your system is wired correctly (database connections, configuration and such).

A functional test can setup the system with in-memory implementations of your application ports, which would make the test run faster and perhaps allow tests to run in parallel (in some cases). The only thing the test cares about is that a feature works as expected. This can reduce the overhead of setting up certain tests, since preparing 3rd party systems with data can be difficult or time consuming.