Try migrating unit tests to satysfi-test

[zeptometer]

Background

At present, we have unit tests and regression tests to keep quality. We write unit tests by writing all test results to output and compare them with snapshots because we don't have unit testing frameworks for SATySFi.

I published the very first version of satysfi-test. I consider we can try it out, and replace all unit tests to ones with satysfi-test if it works well.

Goal

We should have better unit tests using satysfi-test.