Move some test setup/teardown to a central location.

[collin]

I've had a number of groups who end up with quite a bit more test set-up and tear down needs.

To these students I have recommended they add a central ./test-setup.jsand instruct mocha to load this file explicitly and first.

Things that move into this file are setting up globally used mock adapters, the enzyme adapter, and database setup/teardown tasks.

"NODE_ENV='test' mocha ./test-setup \"./server/**/*.spec.js\" \"./client/**/*.spec.js\" \"./script/**/*.spec.js\" --require @babel/polyfill --require @babel/register

// test-setup.js
// with these and other hooks at the top-level.
before(() => db.sync({ force: true });
afterEach(() => db.sync({ force: true });

[glebec]

Sounds reasonable to me.

EDIT: though running database syncs before every test, even frontend / utility / other tests, feels a bit heavy-handed for me.