Better documentation for test helpers, check config messages

[justin808]

• Throw if configuration.generated_assets_dir specified, and using
  webpacker, and if that doesn't match the public_output_path.
• Otherwise, warn if generated_assets_dir is specified
• Fix the setup for tests for spec/dummy so they automatically rebuild
  by correctly setting the source_path in the webpacker.yml
• Updated documentation for the testing setup.

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This change is 

[Judahmeek]

Review status: 0 of 15 files reviewed at latest revision, all discussions resolved, some commit checks broke.

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lib/react_on_rails/configuration.rb, line 40 at r1 (raw file):

      msg = <<-MSG.strip_heredoc
        Error configuring /config/initializers/react_on_rails.rb: You are using webpacker
        and you specified value for generated_assets_dir = #{@configuration.generated_assets_dir}

Should be ...and your specified value...

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Comments from Reviewable

[justin808]

Review status: 0 of 15 files reviewed at latest revision, all discussions resolved, some commit checks broke.

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lib/react_on_rails/configuration.rb, line 40 at r1 (raw file):

Previously, Judahmeek (Judah Meek) wrote…

Should be ...and your specified value...

I'll fix!

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Comments from Reviewable

[coveralls]

Coverage remained the same at ?% when pulling 4d751ea on add-test-for-react-component-hash into b5b4960 on master.

[coveralls]

Coverage remained the same at ?% when pulling d553ced on add-test-for-react-component-hash into b5b4960 on master.

[mapreal19]

some suggestions but feel free to merge and address this later if agreeing with suggestions

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Reviewed 10 of 15 files at r1, 12 of 12 files at r2, 1 of 1 files at r3.
Review status: all files reviewed at latest revision, all discussions resolved.

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lib/react_on_rails/configuration.rb, line 25 at r3 (raw file):

  end

  def self.error_if_using_webpacker_and_generated_assets_dir_not_match_public_output_path

is there a test for this new method?

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lib/react_on_rails/utils.rb, line 9 at r3 (raw file):

require "active_support/core_ext/string"

# Naming: goal is that path is a full_path and dir means relative to the rails root.

what about using full_path and relative_dir or anything better you can think of. The goal is to have self documenting code. If not it would be hard for a reader to find this comment since we could be using this naming pattern in other files

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lib/react_on_rails/webpacker_utils.rb, line 7 at r3 (raw file):

    end

    # Full absolute path of webpacker output files.

instead of writing comments here what about having a spec with this info? In the spec we could see if returning a full path, pathname, etc. Easier to see future errors when upgrading webpacker too.

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lib/react_on_rails/webpacker_utils.rb, line 14 at r3 (raw file):

    def self.bundle_js_file_path_from_webpacker(bundle_name)
      # Note Webpacker 3.4.3 manifest lookup is inside of the public_output_path

remove comment after upgrading 3.4.3?

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Comments from Reviewable

[justin808]

added some tests

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Review status: all files reviewed at latest revision, 4 unresolved discussions.

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lib/react_on_rails/configuration.rb, line 25 at r3 (raw file):

Previously, mapreal19 (Mario Pérez) wrote…

is there a test for this new method?

Yes, added one!

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lib/react_on_rails/utils.rb, line 9 at r3 (raw file):

Previously, mapreal19 (Mario Pérez) wrote…

what about using full_path and relative_dir or anything better you can think of. The goal is to have self documenting code. If not it would be hard for a reader to find this comment since we could be using this naming pattern in other files

good idea! but didn't change much, but one method name.

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lib/react_on_rails/webpacker_utils.rb, line 7 at r3 (raw file):

Previously, mapreal19 (Mario Pérez) wrote…

instead of writing comments here what about having a spec with this info? In the spec we could see if returning a full path, pathname, etc. Easier to see future errors when upgrading webpacker too.

Done.

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lib/react_on_rails/webpacker_utils.rb, line 14 at r3 (raw file):

Previously, mapreal19 (Mario Pérez) wrote…

remove comment after upgrading 3.4.3?

Done.

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Comments from Reviewable

[mapreal19]

Reviewed 13 of 13 files at r4.
Review status: all files reviewed at latest revision, 1 unresolved discussion, some commit checks failed.

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lib/react_on_rails/utils.rb, line 9 at r3 (raw file):

Previously, justin808 (Justin Gordon) wrote…

good idea! but didn't change much, but one method name.

👍

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Comments from Reviewable

[mapreal19]

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Review status: all files reviewed at latest revision, all discussions resolved, some commit checks failed.

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Comments from Reviewable