Add Pry::Env

Env is a helper module to work with environment variables.

lib/pry.rb

@@ -28,6 +28,7 @@ require 'pry/system_command_handler'
 require 'pry/control_d_handler'
 require 'pry/command_state'
 require 'pry/warning'
+require 'pry/env'
 
 Pry::Commands = Pry::CommandSet.new unless defined?(Pry::Commands)
 

lib/pry/env.rb

@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+class Pry
+  # Env is a helper module to work with environment variables.
+  #
+  # @since ?.?.?
+  # @api private
+  module Env
+    def self.[](key)
+      return unless ENV.key?(key)
+
+      value = ENV[key]
+      return if value == ''
+
+      value
+    end
+  end
+end

spec/env_spec.rb

@@ -0,0 +1,26 @@
+# frozen_string_literal: true
+
+RSpec.describe Pry::Env do
+  describe "#[]" do
+    let(:key) { 'PRYTESTKEY' }
+
+    after { ENV.delete(key) }
+
+    context "when ENV contains the passed key" do
+      before { ENV[key] = 'val' }
+      after { ENV.delete(key) }
+
+      specify { expect(described_class[key]).to eq('val') }
+    end
+
+    context "when ENV doesn't contain the passed key" do
+      specify { expect(described_class[key]).to be_nil }
+    end
+
+    context "when ENV contains the passed key but its value is nil" do
+      before { ENV[key] = '' }
+
+      specify { expect(described_class[key]).to be_nil }
+    end
+  end
+end