Feature/estimate

[hirotadashi]

Before submitting this PR, please make sure:

• [ ] Your code builds clean without any errors or warnings
• [ ] You are using approved title ("feat/", "fix/", "docs/", "refactor/")

A description of the changes proposed in the pull request:

Tests performed by the developer:

Tips for QA testing:

[ahmadyazdanii]

@hirotadashi you merged unit-tests again with your changes. I will merge it, but it might cause conflicts that should be fixed.