Prod build generates empty urls and patterns in ngsw.json for Angular Service Worker

[webmaxru]

Versions

Angular CLI: 6.0.0-rc.3
Node: 9.11.1
OS: darwin x64
Angular: 6.0.0-rc.3
... animations, cli, common, compiler, compiler-cli, core, forms
... http, language-service, platform-browser
... platform-browser-dynamic, router, service-worker

Repro steps

ng new testApp2
ng add @angular/pwa --project=testApp2
npm i @angular/service-worker@next --save (to workaround angular/devkit#679 )
ng build --prod

Observed behavior

resulting ngsw.json

{
  "configVersion": 1,
  "index": "/index.html",
  "assetGroups": [
    {
      "name": "app",
      "installMode": "prefetch",
      "updateMode": "prefetch",
      "urls": [],
      "patterns": []
    },
    {
      "name": "assets",
      "installMode": "lazy",
      "updateMode": "prefetch",
      "urls": [],
      "patterns": []
    }
  ],
  "dataGroups": [],
  "hashTable": {}
}

Desired behavior

urls and patterns should be populated by the entries reflecting the assets in dist/testApp2

Mention any other details that might be useful (optional)

This might be connected to the new folder structure - maybe NGSW CLI is still looking for the files in dist folder instead of dist/[projectName]

CC: @Brocco @alxhub

[gkalpak]

There are several problems afaict:

1. The filesystem passed to the Generator here, has outputPath as base. This means that it will list file inside dist/<app-name>/, but the Generator is actually interested in files inside src/.
   EDIT: As @filipesilva pointed out elsewhere, this makes no sense. The current behavior is fine. No idea what I was thinking 😇

2. virtualFs.Host will list files without the leading /, while the Generator (which requests all files here) will try to match the names to globs starting with /.

3. The Generator expects that ALL files will be listed here (unlike how ls and virtualFs.Host work). virtualFs.Host will instead only contain the names of directories, not their deeply nested files.

[hansl]

About point #2; list() is meant to list a directory (think readdir), so no slashes should be involved (as these are file names, not paths).

It seems like #3 is simply not understanding the contracts between the two interfaces. I'm curious how it passes our tests (which means we need to improve coverage).

Seems easy to fix if that's the issue. Whoever fixes this should also include a test that fails before the fix and succeeds after.

[filipesilva]

Have a PR for this in angular/devkit#709.