sometimes CSS ordering fails

[jonathanong]

generally only when i first run tests though. afterwards, the error doesn't pop up again. URGHHH

[timaschew]

not only the first time, but in the most cases it's the first time:

 mocha:runner run suite css-local-ordering +3ms
  css-local-ordering
  remotes:local checking local components at /Users/awilhelm/dev/component-builder2.js/components +1ms
  component-resolver remote not set - defaulting to remotes's defaults +0ms
  component-resolver:locals resolving local at "/Users/awilhelm/dev/component-builder2.js/test/fixtures/css-local-ordering" +1ms
  component-resolver resolving "css-local-ordering" +1ms
  component-resolver:locals resolving "css-local-ordering"'s local dependency "one". +0ms
  component-resolver:locals looking up "css-local-ordering"'s local dependency "one" at "/Users/awilhelm/dev/component-builder2.js/test/fixtures/css-local-ordering/lib/one". +0ms
  component-resolver:locals resolving "css-local-ordering"'s local dependency "two". +0ms
  component-resolver:locals looking up "css-local-ordering"'s local dependency "two" at "/Users/awilhelm/dev/component-builder2.js/test/fixtures/css-local-ordering/lib/two". +4ms
  component-resolver remaining dependencies: 0 +0ms
  component-resolver remaining semver: 0 +0ms
  component-resolver:locals resolving local at "/Users/awilhelm/dev/component-builder2.js/test/fixtures/css-local-ordering/lib/one" +0ms
  component-resolver:locals resolving local at "/Users/awilhelm/dev/component-builder2.js/test/fixtures/css-local-ordering/lib/two" +1ms
  component-resolver resolving "two" +1ms
  component-resolver remaining dependencies: 0 +0ms
  component-resolver remaining semver: 0 +0ms
  component-resolver:locals resolved local "css-local-ordering" +0ms
  component-resolver resolving "one" +0ms
  component-resolver remaining dependencies: 0 +0ms
  component-resolver remaining semver: 0 +0ms
  component-resolver:locals resolved local "css-local-ordering" +0ms
  component-resolver finished resolving locals +0ms
  component-resolver finished resolving dependencies (1) +0ms
  component-resolver finished installing dependencies +0ms
    ✓ should install 
    ✓ should build 
    1) should be correct

  mocha:runner run suite css-url-rewriting +4ms
  css-url-rewriting

  mocha:runner run suite css-url-rewriting-locals +0ms
  css-url-rewriting-locals

  mocha:runner run suite css-glob +0ms
  css-glob

  mocha:runner run suite font-awesome +0ms
  font-awesome

  mocha:runner run suite symlink +0ms
  symlink
  mocha:runner run suite symlink destination option +0ms
    destination option

  mocha:runner finished running +0ms

  69 passing (7s)
  1 failing

  1) css-local-ordering should be correct:

      AssertionError: expected '.two {}\n\n.one {}' to be '.one {}\n\n.two {}'
      + expected - actual

      +".one {}\n\n.two {}"
      -".two {}\n\n.one {}"

      at Assertion.prop.(anonymous function) (/Users/awilhelm/dev/component-builder2.js/node_modules/should/lib/should.js:61:14)
      at Context.<anonymous> (/Users/awilhelm/dev/component-builder2.js/test/styles.js:42:25)
      at callFn (/Users/awilhelm/dev/component-builder2.js/node_modules/mocha/lib/runnable.js:249:21)
      at Test.Runnable.run (/Users/awilhelm/dev/component-builder2.js/node_modules/mocha/lib/runnable.js:242:7)
      at Runner.runTest (/Users/awilhelm/dev/component-builder2.js/node_modules/mocha/lib/runner.js:373:10)
      at /Users/awilhelm/dev/component-builder2.js/node_modules/mocha/lib/runner.js:451:12
      at next (/Users/awilhelm/dev/component-builder2.js/node_modules/mocha/lib/runner.js:298:14)
      at /Users/awilhelm/dev/component-builder2.js/node_modules/mocha/lib/runner.js:308:7
      at next (/Users/awilhelm/dev/component-builder2.js/node_modules/mocha/lib/runner.js:246:23)
      at Immediate._onImmediate (/Users/awilhelm/dev/component-builder2.js/node_modules/mocha/lib/runner.js:275:5)
      at processImmediate [as _immediateCallback] (timers.js:374:17)

[clintwood]

@timaschew, @jonathanong, can confirm it is not only on first run, randomly swaps order... frack, this is breaking things all over the place for me... taking a look at it now...

[jonathanong]

haha dude. i couldn't figure it out because it was so hard to replicate. i'll be impressed if you do!

[clintwood]

hahaha, love a challenge!

Ok, good news I know the source of the issue! Bad news I'm not sure how to fix it!

To reproduce:

1. make it more repeatable: add a few more CSS components to the css-local-ordering test. I added two more components named 'three' & 'four'... I'm on windoze and get the error roughly once every five runs.
2. comment out all except css-local-ordering in ./test/styles.js and target just that test...

To see the issue: replace https://github.com/component/resolver.js/blob/master/lib/locals.js#L177 with

    console.log('A: %s', filename)
    buf = yield fs.readFile.bind(null, filename, 'utf8');
    console.log('B: %s', filename)

What you will see is that the order going in at A: ... is consistent but the order coming out at B: ... sometimes changes... I expected the incoming order to be honored... BTW its not graceful-fs I tried fs and still have this issue. Of course readFileSync eliminates the error but that's probably not what we want here...

@jonathanong, since this is possibly somewhere in fs or generator implementation, how do we resolve it?

[clintwood]

Also just checked if file size affects out order and it's not related... using a large CSS file as say component one does not force it down in the order (due to read time)...

[timaschew]

@jonathanong so found out that it works if I set concurrency of the channel to 1 it never happens.

So either the usage of https://github.com/cojs/chanel is wrong or the library has a bug.

[timaschew]

temporary fix via componentjs/resolver.js@983c1fe