Look into mocha tests

[alschmiedt]

Is your feature request related to a problem? Please describe. We wrote our mocha test setup around 3 years ago now. We want to take another look to make sure that we are using up to date practices after our conversion to goog.module.

Describe the solution you'd like This should be a time boxed issue. Someone shouldn't spend more than a couple hours to a day looking into this. If there is more work than that that needs to be done, then a separate issue should be filed.

Some questions we might want to look into:

• Are we still running mocha tests in the recommended way?
• Should we be including mocha/chai through npm?

Describe alternatives you've considered

Additional context

[maribethb]

My recommendation is:

• Once we have converted the rest of the codebase to ES modules, do the same for the tests.
• Then we can run the mocha tests directly using node, instead of using webdriver.
• We can still have a command that runs the tests in a browser, which is useful for debugging. That command would be similar to our start command though and just start a simple server and launch the test page instead of using webdriver.

Advantages:

• Simpler, matches blockly-samples, and what mocha recommends
• We can get rid of the webdriver dependency
• When running test suites it won't have to open a Chrome window which interrupts you and doesn't shut down properly
• The node runner has a variety of reporters we can use that would make seeing test results and errors much, much nicer when viewed in the console