Feat/mock data

[valentinkononov]

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Short description of what this resolves:

with this change all components, which used data services before, now use abstract classes of service interfaces, mock services extend interface services, CoreModule contains code to inject needed implementation of some service.

By all this, now it's possible to easily change any single service with different mock or with data from api

[dizco]

Out of curiosity, what is the reason why you chose to use abstract classes rather than interfaces, given that you don't implement any function or have any member variables in the abstract classes?

[nnixaa]

Hey @dizco, Angular Injector doesn't support interfaces as tokens (as interfaces are not available at runtime), so, unfortunately, we can only use abstract classes.

[valentinkononov]

yeah, that's right. My first intention was to use interfaces. But then I faced the issue, that Angular Dependency Injector cannot use interface as is. So the decision was to change stuff to abstract classes, behaving more like interfaces

[dizco]

@nnixaa @pinckrow makes total sense. Learn new things every day I guess haha!