BUPH-146 | add support for source override behavior

[jpmarcotte]

This is just for the 1.x branch.

Ticket Description:
If a file getting put into fab already exists in src, then Buphalo skips it. This can make testing the creation of new templates difficult. It also can create cases where it was intended to create a new file with buphalo, but not removing the source file resulted in no net changes.

This could be handled by an env var that has one of 3 values:

SourceOverrideBehavior (what to do if an override is found in the source directory):

• skip (do not write the file; this is the existing default behavior)
• write (write the file anyway; this can be useful for testing and creating new templates)
• throw (throw an exception; this is a safer behavior that forces unambiguous intention)

[dreinhuber]

The logic of the source override behavior implementation looks good/makes sense to me. I think I have some understanding of how the tests are written as well.

I assume since we have a default, this means that the change would be backwards compatible and wouldn't require existing Buphalo setups to include the variable in order to work?

[dreinhuber]

I take it this ensures the default is always being used and line 3 then overrides the default if a variable is provided?

Since it doesn't show in the conversation view, line 3 is:

Neighborhoods\Buphalo\V1\Actor\WriterInterface.SourceOverrideBehavior: '%env(Neighborhoods_Buphalo_V1_Actor_WriterInterface__SourceOverrideBehavior)%'

[jpmarcotte]

Correct. It's not a super-intuitive notation, but as far as I can tell, this is how Symfony handles defaults for environment variables that might not be set. And it makes it so that the code in Buphalo doesn't really have to rely on a "default" and can instead be explicit and know the value will be set.

[jpmarcotte]

This should be good to go, I just never got around to cutting a release (I was leaving it open here until I was ready to actually test it in ListingService). The logic also needs to be implemented for the 2.x branch.