Refactor tests

[anton-trunov]

Closes #346

• I have updated CHANGELOG.md
• I have added tests to demonstrate the contribution is correctly implemented: this usually includes both positive and negative tests, showing the happy path(s) and featuring intentionally broken cases
• I have run all the tests locally and no test failure was reported
• I did not do unrelated and/or undiscussed refactorings

[novusnota]

Absolutely massive!

But I wonder if CLI tests are also exported in npm due to package.json#L28. Also, as of now the whole src/ folder is included too. We may want to optimize that, although that's mostly a nitpick.

Description of files field in package.json

[Gusarich]

This is an amazing improvement to the codebase! The tests were a big and not very structured mess that was only getting worse. Now it'll be easier to contribute and resolve merge conflicts in PRs!

[Gusarich]

What if we also remove the feature- prefix from .spec.ts files in e2e tests?

[anton-trunov]

But I wonder if CLI tests are also exported in npm due to package.json#L28.

good point! fixed

Also, as of now the whole src/ folder is included too. We may want to optimize that, although that's mostly a nitpick.

@novusnota can you please open a new issue about it? we should follow the best practices for npm packaging

What if we also remove the feature- prefix from .spec.ts files in e2e tests?

@Gusarich good point as well! done