Lazy compile in test env

[javan]

• Adds new Webpacker.compile API (that invokes the webpacker:compile rake task)
• Lazily compiles in test env to avoid Webpacker::FileLoader::* exceptions
• Eliminates the need enhance Rails test tasks

Differences from #341

• Doesn't require any changes to an application's test classes
• Doesn't attempt to recompile when files change

[gauravtiwari]

@javan This looks really good 👍 After we discussed the other day I realised that re-compilation isn't necessary if we restart the dev-server/watcher programmatically whenever a pack is added/deleted (at the moment it doesn't). That would be good enough because it will ensure that manifest gets updated, which will ensure that tests will run just fine. I think we will still need #292 to make sure manifest change gets picked up in test environment though.

[dhh]

Lovely! ❤️

/play makeitso

[jackjennings]

Would love to get this in a release—any plans for cutting a new version of the gem with this change soon?

[dhh]

Yeah. Will cut a release tomorrow 👍

…

On May 18, 2017, at 23:58, Jack Jennings ***@***.***> wrote: Would love to get this in a release—any plans for cutting a new version of the gem with this change soon? — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub, or mute the thread.

[gauravtiwari]

Shall we wait until Monday? I was thinking to finish up README PR for this release too.

[dhh]

Sure, that's fine. Do wrap it up. Monday it is then.

…

On Fri, May 19, 2017 at 9:46 AM, Gaurav Tiwari ***@***.***> wrote: Shall we wait until Monday? I was thinking to finish up README PR for this release too. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#360 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAAKtUl78mkcwxU4Slm4zYop5j-hAtoTks5r7UjSgaJpZM4NWr2C> .

[pmk1c]

Is it correct, that I still have to run webpack-dev-server during tests with this change? Seems to be the case. The assets get compiled during test, but the asset url Webpacker generates is "http://localhost:8080/packs/application.js"

EDIT: Switching to current master and regenerating configuration files fixes this. Thanks!

[zacharyw]

Is it best practice to check these compiled test assets into version control, or no?

[javan]

@zacharyw, no. I'd .gitignore them.

[Jeremy-Walton]

@javan I updated my webpacker gem like @pmk1c and now it will generate the public/packs-test when I run my tests. However, once I have that folder, any changes I make to my packs are not being recompiled when I run the tests and I have to delete my public/packs-test folder to get it to regenerate it. Is there something I am doing wrong here? Shouldn't it recompile for the tests when there have been changes made?

[zacharyw]

@Jeremy-Walton I'm seeing the same thing. As a workaround I'm back to manually compiling assets before spec runs:

config.before(:suite) do
  `bin/webpack`
end

[richseviora]

@Jeremy-Walton Also observing the same.
@zacharyw thanks for the workaround!

I think the issue comes from WebPacker::Manifest#lookup, where it'll first attempt to find the manifest and then compile only if not found.

[gauravtiwari]

The idea was to keep this simple but if you need to recompile during tests just call compile on webpacker module:

before(:suite) do
  Webpacker.compile
end

[gauravtiwari]

The above will ensure that packs are recompiled and manifest is reloaded - ref:

webpacker/lib/webpacker.rb

Line 10 in 549988b

def compile

[richseviora]

It sounds like we save unnecessary compilation calls at the expense of introducing an implicit requirement that the user invokes WebPacker.compile (manually or before suite execution) whenever their JS code changes.

Is there a better way we could communicate this? I totally appreciate that we don't want to recompile the entire pack for every test run, but I think a lot of users are going to run into similar concerns.

[justin808]

@richseviora See #464. Also, I wrote the code for React on Rails that does this. We use the file mtimes.

[gauravtiwari]

Yepp, actually there was a PR made (#341 - https://github.com/rails/webpacker/pull/341/files#diff-23ac5b11daf84548b507c40511c4aa2eR21) to add very same feature but in the end went with more simpler and implicit solution.

Perhaps we should add that too so both options work

// cc @javan

[raldred]

For me the cached version would be favourable. The speed of compilation whilst not an issue on CI is pretty frustrating developing locally. Particularly on a large react app.

[stevehanson]

Compiling webpack in the before(:suite) every time I ran my tests was slowing me down quite a bit, so I ended up pulling @gauravtiwari's solution from his now-closed PR #341 into my codebase (slightly modified), and it's working great for me.

Using his approach, Webpack now only compiles if my source has changed. Thanks @gauravtiwari for that and for all of your diligent work on this gem. Would love to see your solution included into the Webpacker gem, as I think the functionality would be broadly useful.

For anyone looking for a quick fix, here is a gist of the code I ended up using, or check out PR #341.

[raldred]

Thanks for sharing @stevehanson I wonder if #341 could be reopened and included as well. Both gives everyone the option depending on their use.

[gauravtiwari]

@stevehanson Thanks for sharing. Looks great 👍

@raldred @stevehanson Seems like there is real requirement for this so I will reopen #341 and we can review it together. It would be nice to have both options.

[kernow]

I've just run into this issue too, a solution where webpack is recompiled only when something has changed before the test suite is run is whats needed IMHO. 👍 for something like #341