IAVL Dependency Inversion Refactor - investigate and create issues

[p0mvn]

Background

There are a few dependencies on structs instead of interfaces. This is a violation of the dependency inversion principle. Instead of depending on concrete implementations, we should be depending on abstractions. The most problematic examples are in the mutable and the immutable tree where we have nodeDb member as a struct instead of an interface.

Such violations make the system more brittle because a change in the concrete implementation may affect the code across the system. In addition, it makes it more difficult to test the structs that depend on the concrete implementations because we cannot mock them. Only interfaces can be mocked with gomock. For example, since nodeDB is not an interface, to test the mutable tree, we are forced to mock the database interface instead.

Therefore, we would like to investigate the codebase and create issues for all occurrences of the violation of the dependency inversion principle similar to mutable and immutable trees depending on the.

Acceptance Criteria

• The project is investigated for dependency inversion principle violations described above.
• For each violation, an issue is created to perform the refactor (Example: IAVL Dependency Inversion Refactor - create nodeDB interface for immutable and mutable trees #15 )
• Link all new issues to this parent issue

[p0mvn]

One more relevant issue: #24

[p0mvn]

Given how risky changes on IAVL are. I think that this refactor is not worth the effort so I'm going to close this. Please let me know if any concerns