Closes#1012
- This is the first change for the dependency injection. This change
adds `DIContainer` which is used to register and resolve dependencies.
- Then this change shows how `DIContainer` can be used to resolve
dependencies. And it also shows how to mock dependencies in tests.
- Constructors of `Initializer` are changed to support mocking of
depedendencies. But it doesn't affect public API in any way.
- Depedencies are registered in `Dependencies.setup()`. Then in the code
`container.resolve(SomeType.self)` is called to get instance of the
dependency.
- `ZcashTestCase` class is added. It inherits from `XCTestCase` and
should be used for base class in tests. `ZcashTestCase` takes care of
creation of `DIContainer` for dependencies mocking. In future we can
maybe move there more things that are used in each test.
- Lot is missing here. Not all the code is using dependency injection.
Tests for `DIContainer` are missing. Only `OfflineTests` work now
(other tests can't be even compiled). It will be added in future
changes.
5d2b2298b5