Support test rails enviroment about webpacker

[dhh]

We don't have any integration for compiling for tests in webpack at the moment. If you need webpack assets available for testing, then you currently have to compile them yourself.

[naps62]

@p0wl In case you're interested, here's a snippet that will only run bin/webpack if at least one JS test is run, and only if there's been updates to files in app/javascript since the last test build

https://gist.github.com/naps62/a7dcce679a45592714ea6477108f0419

[zhumo]

It doesn't seem like the before(:suite) would work. Maybe I am doing something wrong and if that's the case, please do let me know!

I tried before(:suite) and I think what happens is that the backticks kick off a subprocess. So the specs are running while webpack is compiling. Therefore, some specs fail raising that there is no such pack, while others succeed. This success and failure happen non-deterministically.

The second time that you run the specs, the files have been compiled, so there are fewer failures, but it's not guaranteed that any changes to the files since then will have made it through the compilation.

For now, I'm running RAILS_ENV=test bin/webpack before I run the specs. But it'd be great to have a hook in the rspec command line or some other automatic thing. I wonder, for the 5.1 release, what will the recommended course of action be?

Update

Never mind! Actually, I got it to work by putting Webpacker::Manifest.load after the bin/webpack command. Before bin/webpack runs, Webpacker::Manifest.instance thinks there is no manifest-test.json file. You have to reload the instance and it'll appear.

[p0wl]

We played around with different approaches, e.g. trying to only execute webpack if at least one spec needs it (via :js group or similar), but we ended up running webpack before :suite:

  # spec/rails_helper.rb
  config.before :suite do
    # Run webpack compilation before suite, so assets exists in public/packs
    # It would be better to run the webpack compilation only if at least one :js spec
    # should be executed, but `when_first_matching_example_defined`
    # does not work with `config.infer_spec_type_from_file_location!`
    # see https://github.com/rspec/rspec-core/issues/2366
    `bin/webpack`
  end

for js tests we use jest (and babel-jest for transpiling), so no webpack involved there.

[taystack]

I know this is closed, but I am running into the same issue with running my controller specs. To be clear, should I be putting a command within my config/environments/test.rb that runs the webpack executable from /bin?

[stereoscott]

I'm interested to hear how others got this working. For now we are just running webpack before we run our test suite, but it would be nice for to compile automatically before we run the integration tests. Maybe add it to bin/rspec or in a RSpec.configure { |config| config.before(:suite) ... } block...

[taystack]

@zhumo not sure if you ran into the same problem, but making your change threw a parse error in /config/webpack/shared.js when running rspec:

const { basename, dirname, join, resolve } = require("path");
//    ^

It's kinda smelly, but changing those imports to:

const P = require("path")
const basename = P.basename;
// ...

seems to fix the symptom. I had to change all files where the unpacking of require was done. I would prefer to NOT do this. If anyone has any suggestions I'm all ears. This all feels like a hack to me.

[zhumo]

@taystack I did not run in to that issue. I am befuddled as to why that is happening for you because I think require("path") is looking at a library external to both rails and webpacker.

[zhumo]

@taystack Maybe I found your problem? #192. If you follow through to the PR, you'll see that it requires node >= 6.4.0.