Fix load to respect existing environment variables over env file when…

… doing variable interpolation

lib/dotenv.rb

@@ -12,7 +12,7 @@ class << self
  def load(*filenames)
  with(*filenames) do |f|
  ignoring_nonexistent_files do
- env = Environment.new(f)
+ env = Environment.new(f, true)
  instrument("dotenv.load", env: env) { env.apply }
  end
  end
@@ -21,7 +21,7 @@ def load(*filenames)
  # same as `load`, but raises Errno::ENOENT if any files don't exist
  def load!(*filenames)
  with(*filenames) do |f|
- env = Environment.new(f)
+ env = Environment.new(f, true)
  instrument("dotenv.load", env: env) { env.apply }
  end
  end
@@ -30,7 +30,7 @@ def load!(*filenames)
  def overload(*filenames)
  with(*filenames) do |f|
  ignoring_nonexistent_files do
- env = Environment.new(f)
+ env = Environment.new(f, false)
  instrument("dotenv.overload", env: env) { env.apply! }
  end
  end

lib/dotenv/environment.rb

@@ -4,13 +4,13 @@ module Dotenv
  class Environment < Hash
  attr_reader :filename
 
- def initialize(filename)
+ def initialize(filename, is_load)
  @filename = filename
- load
+ load(is_load)
  end
 
- def load
- update Parser.call(read)
+ def load(is_load)
+ update Parser.call(read, is_load)
  end
 
  def read

lib/dotenv/parser.rb

@@ -32,14 +32,15 @@ class Parser
  class << self
  attr_reader :substitutions
 
- def call(string)
- new(string).call
+ def call(string, is_load)
+ new(string, is_load).call
  end
  end
 
- def initialize(string)
+ def initialize(string, is_load)
  @string = string
  @hash = {}
+ @is_load = is_load
  end
 
  def call
@@ -74,7 +75,7 @@ def parse_value(value)
 
  if Regexp.last_match(1) != "'"
  self.class.substitutions.each do |proc|
- value = proc.call(value, @hash)
+ value = proc.call(value, @hash, @is_load)
  end
  end
  value

lib/dotenv/substitutions/command.rb

@@ -20,7 +20,7 @@ class << self
  )
  /x
 
- def call(value, _env)
+ def call(value, _env, _is_load)
  # Process interpolated shell commands
  value.gsub(INTERPOLATED_SHELL_COMMAND) do |*|
  # Eliminate opening and closing parentheses

lib/dotenv/substitutions/variable.rb

@@ -18,17 +18,27 @@ class << self
  \}? # closing brace
  /xi
 
- def call(value, env)
+ def call(value, env, is_load)
+ combined_env = if is_load
+ env.merge(ENV)
+ else
+ ENV.to_h.merge(env)
+ end
  value.gsub(VARIABLE) do |variable|
  match = $LAST_MATCH_INFO
+ substitute(match, variable, combined_env)
+ end
+ end
+
+ private
 
-  if match[1] == '\\'
-  variable[1..-1]
- elsif match[3]
-  env.fetch(match[3]) { ENV[match[3]] }
- else
-  variable
- end
+ def substitute(match, variable, env)
+ if match[1] == '\\'
+ variable[1..-1]
+ elsif match[3]
+ env.fetch(match[3], "")
+ else
+ variable
  end
  end
  end

spec/dotenv/environment_spec.rb

@@ -11,7 +11,7 @@
 
  it "fails if file does not exist" do
  expect do
- Dotenv::Environment.new(".does_not_exists")
+ Dotenv::Environment.new(".does_not_exists", true)
  end.to raise_error(Errno::ENOENT)
  end
  end
@@ -47,7 +47,7 @@ def env(text)
  file = Tempfile.new("dotenv")
  file.write text
  file.close
- env = Dotenv::Environment.new(file.path)
+ env = Dotenv::Environment.new(file.path, true)
  file.unlink
  env
  end

spec/dotenv/parser_spec.rb

@@ -2,7 +2,7 @@
 
 describe Dotenv::Parser do
  def env(string)
- Dotenv::Parser.call(string)
+ Dotenv::Parser.call(string, true)
  end
 
  it "parses unquoted values" do
@@ -55,11 +55,23 @@ def env(string)
  .to eql("FOO" => "test", "BAR" => "testbar")
  end
 
- it "reads variables from ENV when expanding if not found in local env" do
+ it "expands variables from ENV if not found in .env" do
  ENV["FOO"] = "test"
  expect(env("BAR=$FOO")).to eql("BAR" => "test")
  end
 
+ it "expands variables from ENV if found in .env during load" do
+ ENV["FOO"] = "test"
+ expect(env("FOO=development\nBAR=${FOO}")["BAR"])
+ .to eql("test")
+ end
+
+ it "doesn't expand variables from ENV if in local env in overload" do
+ ENV["FOO"] = "test"
+ expect(env("FOO=development\nBAR=${FOO}")["BAR"])
+ .to eql("test")
+ end
+
  it "expands undefined variables to an empty string" do
  expect(env("BAR=$FOO")).to eql("BAR" => "")
  end

spec/dotenv_spec.rb

@@ -10,7 +10,8 @@
  let(:env_files) { [] }
 
  it "defaults to .env" do
- expect(Dotenv::Environment).to receive(:new).with(expand(".env"))
+ expect(Dotenv::Environment).to receive(:new).with(expand(".env"),
+ anything)
  .and_return(double(apply: {}, apply!: {}))
  subject
  end
@@ -22,7 +23,7 @@
  it "expands the path" do
  expected = expand("~/.env")
  allow(File).to receive(:exist?) { |arg| arg == expected }
- expect(Dotenv::Environment).to receive(:new).with(expected)
+ expect(Dotenv::Environment).to receive(:new).with(expected, anything)
  .and_return(double(apply: {}, apply!: {}))
  subject
  end
@@ -55,10 +56,17 @@
  end
 
  describe "load" do
+ let(:env_files) { [] }
  subject { Dotenv.load(*env_files) }
 
  it_behaves_like "load"
 
+ it "initializes the Environment with a truthy is_load" do
+ expect(Dotenv::Environment).to receive(:new).with(anything, true)
+ .and_return(double(apply: {}, apply!: {}))
+ subject
+ end
+
  context "when the file does not exist" do
  let(:env_files) { [".env_does_not_exist"] }
 
@@ -70,10 +78,17 @@
  end
 
  describe "load!" do
+ let(:env_files) { [] }
  subject { Dotenv.load!(*env_files) }
 
  it_behaves_like "load"
 
+ it "initializes Environment with truthy is_load" do
+ expect(Dotenv::Environment).to receive(:new).with(anything, true)
+ .and_return(double(apply: {}, apply!: {}))
+ subject
+ end
+
  context "when one file exists and one does not" do
  let(:env_files) { [".env", ".env_does_not_exist"] }
 
@@ -88,6 +103,12 @@
  subject { Dotenv.overload(*env_files) }
  it_behaves_like "load"
 
+ it "initializes the Environment with a falsey is_load" do
+ expect(Dotenv::Environment).to receive(:new).with(anything, false)
+ .and_return(double(apply: {}, apply!: {}))
+ subject
+ end
+
  context "when loading a file containing already set variables" do
  let(:env_files) { [fixture_path("plain.env")] }