Add more tests

[tsukhu]

• I'm submitting a ...
  [ ] bug report
  [x] feature request
  [ ] question about the decisions made in the repository

• Do you want to request a feature or report a bug?
  A lot of functionality has been added lately and there is a need to add more tests. In future we will focus on TDD , but for now lets catch up with the missing set of tests.

• What is the current behavior?

• If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem

• What is the expected behavior?

• What is the motivation / use case for changing the behavior?

• Please tell us about your environment:

• nxplorer version: 1.5.6
• other environment details

• Other information (e.g. detailed explanation, stacktraces, related issues, suggestions how to fix, links for us to have context, eg. npm , github, stackoverflow etc)