Add --install-dependencies option for phoenix.new

[drewblas]

Allows for programmatic running of phoenix.new without a shell prompt.

I did try adding a test, but the mix_shell message still throws an error because of some other input interaction. I think maybe this tiny flag doesn't need a test?

  test "new with --install-dependencies option" do
    in_tmp "new with --install-dependencies option" do
      Mix.Tasks.Phoenix.New.run [@app_name]
      refute_received {:mix_shell, :yes?, ["\nFetch and install dependencies?"]}
    end
  end

1) test new with --install-dependencies option (Mix.Tasks.Phoenix.NewTest)
     test/phoenix_new_test.exs:369
     ** (RuntimeError) no shell process input given for yes?/1
     stacktrace:
       (mix) lib/mix/shell/process.ex:155: Mix.Shell.Process.yes?/1
       (mix) lib/mix/generator.ex:20: Mix.Generator.create_file/3
       (phoenix_new) lib/phoenix_new.ex:505: anonymous fn/5 in Mix.Tasks.Phoenix.New.copy_from/3
       (elixir) lib/enum.ex:1385: Enum."-reduce/3-lists^foldl/2-0-"/3
       (phoenix_new) lib/phoenix_new.ex:494: Mix.Tasks.Phoenix.New.copy_from/3
       (phoenix_new) lib/phoenix_new.ex:206: Mix.Tasks.Phoenix.New.run/4
       test/phoenix_new_test.exs:371

[chrismccord]

Piping to yes should accommodate this, right?

[drewblas]

That's true in a general sense. Although most command line tools provide the option as well so that you don't need to "hack" around it with | yes.

So this brings it to be similar to other tools, like with mix archive.install: https://github.com/elixir-lang/elixir/blob/master/lib/mix/lib/mix/tasks/archive.install.ex#L27

Also, piping to | yes means answering yes to everything. But the user may want yes for some answers and no for others (like no to overwriting a file). Currently I think there's just the one phoenix prompt, but that could easily change (especially if a user has extra plugins that might start modifying how phoenix generates files).

[chrismccord]

May I ask your usecase for programmatically calling the generators? I'm hesitant adding options around this because they could change in the future and I haven't see a usecase yet that requires them

[josevalim]

Btw, yes | is a bad idea for long running tasks because it makes your memory grow if the data is not being consumed. I agree with @chrismccord I would like to hear use cases though before we add more options.

[drewblas]

I have two use cases:

1. I built https://github.com/drewblas/phoenix_upgrades to be able to compare how the phoenix new generators / boilerplate changes over time (as a complement to Chris' upgrade instructions)
2. I'm working to build a more advanced set of generators (ala Rails Wizards or Rails Apps Composer) that starts with the base-generated app and then adds more based on user selections.

Quick note: I don't think this is ready to merge yet. What I realized when doing the first app is that I actually want to be able to explicitly answer 'no', not 'yes'. So this PR needs to be expanded to support --[no-]install-dependencies. But I'd like to get your feedback on if you will allow this command option before I go through the work of adding even more. Either way, thanks so much!

[josevalim]

I think this is a reasonable use case. Let's see what @chrismccord thinks too! Thanks for expanding @drewblas!

[chrismccord]

I agree it's definitely reasonable for what you want to achieve. Thanks for elaborating. Proceed!

[chrismccord]

@drewblas ping. How are we coming on this one?

[chrismccord]

@drewblas I'm closing for now. Please ping if you're up for completing this and I'll reopen. Thanks!