Ignore --no-dev option for dependency resolution & lock file generation

[naderman]

As per #5013 (comment) I think the --no-dev option should only impact the installation part of the update command. The resolution and lock file generation should always include dev packages, to ensure consistent generation of the lock file, regardless of weather --no-dev is passed or not. The option should remain, to choose whether dev packages should really be downloaded and installed.

As a side effect this should simplify some of the code in Composer\Installer.

[Seldaek]

See #5224 - it wasn't quite the Easy Pick after all ;)

[naderman]

Wow indeed, quite a lot of code!

[Seldaek]

Yeah it forced quite a bit of restructuring to avoid code duplication. It doesn't really hurt though to have smaller methods.

[jpuck]

Hi @naderman could you please elaborate on what you mean by:

The resolution and lock file generation should always include dev packages, to ensure consistent generation of the lock file, regardless of weather --no-dev is passed or not.

I'm having trouble wrapping my head around the issue here. After #5224 a lot of people are having trouble with this I think mostly because folks develop in more advanced environments than those deployed into.

Thanks!

[naderman]

@jpuck That error can only happen if you run install without a lock file, which you should never do in a non-dev environment. Feel free to suggest an update to the docs to make this clearer in a separate issue.