Implement Rails.app_env

Author: tangrufus

lib/rails/app_env/helpers.rb

@@ -0,0 +1,11 @@
+module Rails
+  module AppEnv
+    module Helpers
+      def app_env
+        return Rails.env unless ENV["APP_ENV"].present?
+
+        @_app_env ||= ActiveSupport::EnvironmentInquirer.new(ENV["APP_ENV"])
+      end
+    end
+  end
+end

lib/rails/app_env/railtie.rb

@@ -1,6 +1,11 @@
+require_relative "helpers"
+
 module Rails
   module AppEnv
     class Railtie < ::Rails::Railtie
+      config.before_configuration do
+        ::Rails.extend(Helpers)
+      end
     end
   end
 end

test/env_helpers.rb

@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+require "rails"
+
+module EnvHelpers
+  private
+    def with_rails_env(env, &block)
+      Rails.instance_variable_set :@_env, nil
+      switch_env "RAILS_ENV", env do
+        switch_env "RACK_ENV", nil, &block
+      end
+    end
+
+    def switch_env(key, value)
+      old, ENV[key] = ENV[key], value
+      yield
+    ensure
+      ENV[key] = old
+    end
+end

test/rails/app_env/helpers_test.rb

@@ -0,0 +1,98 @@
+require_relative "../../env_helpers"
+
+class Rails::AppEnvTest < ActiveSupport::TestCase
+  include EnvHelpers
+
+  DEFAULT_RAILS_ENV = "development"
+
+  test "Rails.app_env is an instance of EnvironmentInquirer when APP_ENV is present" do
+    switch_env "APP_ENV", nil do
+      assert_instance_of ActiveSupport::EnvironmentInquirer, Rails.app_env
+    end
+  end
+
+  test "Rails.app_env is an instance of EnvironmentInquirer when APP_ENV is blank" do
+    switch_env "APP_ENV", "foo" do
+      assert_instance_of ActiveSupport::EnvironmentInquirer, Rails.app_env
+    end
+  end
+
+  test "Rails.app_env is set from APP_ENV" do
+    switch_env "APP_ENV", "foo" do
+        assert_equal "foo", Rails.app_env
+    end
+  end
+
+  test "Rails.app_env is set from APP_ENV when both APP_ENV are RAILS_ENV present" do
+    switch_env "APP_ENV", "foo" do
+      with_rails_env("bar") do
+        assert_equal "foo", Rails.app_env
+        assert_equal "bar", Rails.env
+      end
+    end
+  end
+
+  test "Rails.app_env is set from APP_ENV when APP_ENV is present but not RAILS_ENV" do
+    switch_env "APP_ENV", "foo" do
+      with_rails_env(nil) do
+        assert_equal "foo", Rails.app_env
+        assert_equal DEFAULT_RAILS_ENV, Rails.env # Default Rails environment
+      end
+    end
+  end
+
+  test "Rails.app_env falls back to Rails.env when APP_ENV is blank" do
+    switch_env "APP_ENV", nil do
+      with_rails_env("foo") do
+        assert_equal "foo", Rails.app_env
+        assert_equal "foo", Rails.env
+        assert_same Rails.env, Rails.app_env
+      end
+    end
+  end
+
+  test "Rails.app_env falls back to Rails.env when APP_ENV is blank and follow its changes" do
+    switch_env "APP_ENV", nil do
+      with_rails_env("foo") do
+        Rails.env = "bar"
+
+        assert_equal "bar", Rails.app_env
+        assert_equal "bar", Rails.env
+        assert_same Rails.env, Rails.app_env
+      end
+    end
+  end
+
+  test "Rails.app_env falls back to Rails.env when both APP_ENV and RAILS_ENV are blank" do
+    switch_env "APP_ENV", nil do
+      with_rails_env(nil) do
+        assert_equal DEFAULT_RAILS_ENV, Rails.app_env
+        assert_equal DEFAULT_RAILS_ENV, Rails.env # Default Rails environment
+        assert_same Rails.env, Rails.app_env
+      end
+    end
+  end
+
+  test "Rails.app_env falls back to Rails.env when both APP_ENV and RAILS_ENV are blank and follow its changes" do
+    switch_env "APP_ENV", nil do
+      with_rails_env(nil) do
+        Rails.env = "foo"
+
+        assert_equal "foo", Rails.app_env
+        assert_equal "foo", Rails.env
+        assert_same Rails.env, Rails.app_env
+      end
+    end
+  end
+
+  test "Rails.app_env is set from APP_ENV and does not follow Rails.env changes" do
+    switch_env "APP_ENV", "foo" do
+      with_rails_env("bar") do
+        Rails.env = "baz"
+
+        assert_equal "foo", Rails.app_env
+        assert_equal "baz", Rails.env
+      end
+    end
+  end
+end