I need to create a specific product import extension for a project. In the project, Magento Enterprise will be used. I learned in an old article that I can develop and test the extension with the community edition and it will also work in the enterprise edition, is that still true? If not is there a way for developers to get a copy of the Enterprise edition?
That is not correct. Magento Enterprise edition contains more features and, for that reason, there are differences in the codebase.
If you are planning to support EE in your extension, then the right way of moving forward with the development is by using EE as platform.
@oliverodermatt You may be knowing that EE is paid software, so access to it is not freely available. As you said you have to create the module for project than get the copy of code from your client and use the same for development. If for some reason you cannot get the code soon than you can start developing the extension on Magento CE.
However, EE and CE has different code base.Once you have code ready then test it on EE once you get the access. You may have to make some adjustment to make your code working on EE.