Fix load to respect existing environment variables over env file when doing variable interpolation

[cbjoseph]

Closes issue #319.

[cadwallion]

👋 @cbjoseph !

Apologies that this has been sitting for so long, I'm part of a trio of new maintainers of this project, and we're trying to clear out the backlog of folks waiting for responses.

There appears to be a merge conflict associated with some of our work clearing up said backlog. Could you please resolve the conflict so I can review?

Thank you!

[cbjoseph]

@cadwallion resolved conflicts! Thanks for taking a look.

[jonmagic]

@cbjoseph it looks like there is one rubocop error:

lib/dotenv/substitutions/variable.rb:44:1: C: Trailing whitespace detected.

I believe fixing that up should be the last step.

[cbjoseph]

@jonmagic oops! fixed rubocop error, should be all good now

[cadwallion]

Looks good, thanks for the contribution!

[nijikon]

I think that something is still off with the implementation.

balrog:~ n$ cat .env
TEST=5
TEST_COMBINED=combined_${TEST}
balrog:~ n$ TEST=10 ruby dotenv.rb
Before loading .env...

TEST=10
TEST_COMBINED=

{"TEST"=>"5", "TEST_COMBINED"=>"combined_10"}
After loading .env...

TEST=5
TEST_COMBINED=combined_10

#!/usr/bin/env ruby
# frozen_string_literal: true

def display_envs()
  puts
  puts "TEST=#{ENV['TEST']}"
  puts "TEST_COMBINED=#{ENV['TEST_COMBINED']}"
  puts
end

puts "Before loading .env..."
display_envs

require 'dotenv'
puts Dotenv::Environment.new('.env', true).inspect
ENV.update(Dotenv::Environment.new('.env', true))

puts "After loading .env..."
display_envs

[nijikon]

/cc @cbjoseph @cadwallion

[cbjoseph]

@cadwallion Can you comment on expectation of this Environment class? My assumption was that it's an internal tool, since it seems undocumented. Could you provide more context on its use case?

[jessedoyle]

This change just caught us off guard as well with a gem update.

@cbjoseph: Is it documented anywhere that Dotenv::Environment is internal and subject to breaking changes?

Ideally, any changes to a public method signature should be backwards compatible.

What does everyone think about making the is_load parameter here default to true?

i.e.

def initialize(filename, is_load = true)
  @filename = filename
  load(is_load)
end

[KrauseFx]

I also wanted to jump in that this broke many setups for fastlane and fastlane.ci, as it was introduced with a minor version bump. Adding a default parameter with #345 sounds like a great fix 👍

[EvanHahn]

Curious to know if Dotenv::Environment should be considered public given that it's not documented.