Add testing section to addon guide

[simonihmig]

Provides some explanations on how to test addons for FastBoot compatibility, including useful addon links.

[stefanpenner]

@kratiahuja I think we want to revisit this, as the existing ember-cli-addon tests are a tad on the slow side right?

[simonihmig]

You refer to running test straight from the addon's dummy app, right? I am not so sure you can always do that:

• addons often don't add ember-cli-fastboot as a devDependency
• the dummy app might be used to drive a demo page (as acceptance tests are often not needed)
• addons might want to test different scenarios, that need different setups not possible with a single dummy app. E.g. different deps (pre and post 1.0 FastBoot tests in Prepare for FastBoot 1.0 ember-cli-head#21) or fixtures (https://github.com/simplabs/ember-simple-auth/tree/master/fastboot-tests)

So I think ember-cli-addon-tests based testing has still its valid use cases, though when you can do the same using the dummy app, that is certainly preferable...

[kratiahuja]

@simonihmig I think we can run ember-cli-fastboot test atleast using the dummy addon. Other addons may need to write FastBoot tests with testing against ember canary but we need to re-work the testing strategy in general. It is extremely slow and fragile to write tests using ember-cli-addon-tests since the copy and linking on npm packages and creating app takes a long time. Morevoer yarn doesn't work as well. Agreed we need a solution for addons but we need to make ember-cli-addon-tests fast first.

[sdhull]

I won't pretend I've tried any of these packages (yet) but here's another (newer) one that looks promising: https://github.com/embermap/ember-cli-fastboot-testing/