Feature/test UseCase

[andoshin11]

Summary

• Add factory methods for Store, Repository, and Service
• Setup unit test environment with Jest
• Write unit test for UseCase with Sinon.js
• Run unit test on Circle CI
• Send coverage report to Codecov.io

What kind of change does this PR introduce? (check at least one)

• [ ] Bugfix
• [x] Feature
• [ ] Code style update
• [ ] Refactor
• [x] Build-related changes
• [ ] Other, please describe:

The PR fulfills these requirements:

• [ ] When resolving a specific issue, it's referenced in the PR's title (e.g. fix #xxx[,#xxx], where "xxx" is the issue number)
• [x] All lines for debugging use are removed
• [x] All tests are passing
• [x] Lint checks are passing
• [x] New/updated tests are included

If adding a new feature, the PR's description includes:

• [ ] A convincing reason for adding this feature (to avoid wasting your time, it's best to open a suggestion issue first and wait for approval before working on it)

Screenshots

Other information:

[codecov[bot]]

Codecov Report

:exclamation: No coverage uploaded for pull request base (master@54bef03). Click here to learn what that means. The diff coverage is n/a.

@@           Coverage Diff           @@
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  Coverage          ?   100%           
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  Files             ?      1           
  Lines             ?     10           
  Branches          ?      0           
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  Hits              ?     10           
  Misses            ?      0           
  Partials          ?      0

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