add testing environment

[sgratzl]

Prerequisites:

• Unless it is a hotfix it should be merged against the dev branch
• Branch is up-to-date with the branch to be merged with, i.e. dev
• Build is successful
• Code is cleaned up and formatted

Summary

• adds https://jestjs.io/ for unit-testing together with https://testing-library.com/docs/svelte-testing-library/intro -> see .spec files in src directory
• adds https://www.cypress.io/ for e2e testing, see cypress/integrations spec files for examples
• small refactoring for easier testing

usage -> see README section

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[dlaliberte]

I reviewed the jest and cypress web sites and docs, and it all looks good to me. The main question I would have is whether they work well with Svelte, given it's particular design characteristics.

[sgratzl]

for cypress it doesn't make a difference since it is working with the website. for Jest, I use https://testing-library.com/docs/svelte-testing-library/intro which should deal with Svelte characteristics

[tildechris]

The testing framework here LGTM, but there's a lot to review.

I think I understand the test hooks and writing tests, but I do not understand the changes around msa.csv.js and friends. Can you summarize?

[sgratzl]

I think I understand the test hooks and writing tests, but I do not understand the changes around msa.csv.js and friends. Can you summarize?

importing non JavaScript files (like CSV) in JavaScript files usually requires a bundler like webpack or rollup with a custom loader. However, now we also have Jest in the loop which compiles the test code and thus also needs to handle to those kind of imports files. To avoid a more complicated test setup, I wrapped the CSV files to JavaScript modules, similar to what the current raw-loader of webpack was doing before.

[tildechris]

That sounds reasonable. LGTM, thanks for the work here.