I'm not sure that I understand all of that, so I'm probably not the right one to review it.
For my own understanding: The Qml Plugin gets automatically loaded when we start the qml engine? Because I don't see it anywhere getting loaded in the main.cpp file.
Personally I would prefer that only the type registration is moved to the plugin and that elisaapplications.cpp etc. would still get created in the main.cpp file. That would keep the code more readable

In D11737#236025, @astippich wrote:

I'm not sure that I understand all of that, so I'm probably not the right one to review it.

It is the standard way to have code that can be loaded by a Qml engine. This is the way Kirigami works for example.

For my own understanding: The Qml Plugin gets automatically loaded when we start the qml engine? Because I don't see it anywhere getting loaded in the main.cpp file.

Yes, the import lines will do exactly that.

Personally I would prefer that only the type registration is moved to the plugin and that elisaapplications.cpp etc. would still get created in the main.cpp file. That would keep the code more readable

I will have a look at what I can do here.

In fact, the goal is to be able to run automatic tests of qml components that may require the c++ code and the global variable elisa.
The other important thing is to reduce compilation time by not compiling n times each cpp files.

In D11737#250233, @mgallien wrote:

In fact, the goal is to be able to run automatic tests of qml components that may require the c++ code and the global variable elisa.
The other important thing is to reduce compilation time by not compiling n times each cpp files.

That would be cool indeed, but I still would prefer if this can be done without pushing elisapplication to the plugin loader. The other projects I looked at use the plugin loader to pass the types to qml, but I haven't seen anyone relying on the plugin loader for basically the whole application logic.
Is it be possible to create another plugin just for the tests?

In D11737#255482, @mgallien wrote:

I plan to do the following steps:

• put all c++ code in a shared library for use by the applications, the qml plugin and the automatic tests ;
• put the creation of elisa main variable in elisa application ;
• ensure the qml test that needs c++ code still works with a locally created instance of elisa application.
  
  This way, we should be able to reduce a lot compilation time. We should be able to have a usable qml plugin for the automatic tests. We should also keep creating the ElisaApplication instance in the main.cpp file. Does it sound good for you ?

That sounds like a good plan, thanks!

Works flawlessly! One question below