re-add env defaults support

README.md

@@ -88,7 +88,7 @@ defaults from environment variables:
 
 ```ruby
 class Config < Hashr
-  extend Hashr::EnvDefaults
+  extend Hashr::Env
 
   self.env_namespace = 'foo'
 

lib/hashr.rb

@@ -1,6 +1,6 @@
 class Hashr < BasicObject
   require 'hashr/core_ext/ruby/hash'
-  require 'hashr/env_defaults'
+  require 'hashr/env'
 
   class << self
     attr_reader :defaults
@@ -46,7 +46,7 @@ def [](key)
   end
 
   def []=(key, value)
-    @data.store(to_key(key), value.is_a?(::Hash) ? self.class.new(value, {}) : value)
+    @data.store(to_key(key), value.is_a?(::Hash) ? ::Hashr.new(value, {}) : value)
   end
 
   def values_at(*keys)
@@ -95,7 +95,7 @@ def is_a?(const)
   alias kind_of? is_a?
 
   def inspect
-    "<Hashr #{@data.inspect}>"
+    "<#{self.class.name} #{@data.inspect}>"
   end
 
   private

lib/hashr/env.rb

@@ -0,0 +1,48 @@
+class Hashr
+  module Env
+    class Vars < Struct.new(:defaults, :namespace)
+      FALSE = [false, nil, 'false', 'nil', '']
+
+      def to_h
+        defaults.deep_merge(read_env(defaults, namespace.dup))
+      end
+
+      private
+
+        def read_env(defaults, namespace)
+          defaults.inject({}) do |result, (key, default)|
+            keys = namespace + [key]
+            value = default.is_a?(Hash) ? read_env(default, keys) : var(keys, default)
+            result.merge(key => value)
+          end
+        end
+
+        def var(keys, default)
+          key = keys.map(&:upcase).join('_')
+          value = ENV.fetch(key, default)
+          cast(value, default, keys)
+        end
+
+        def cast(value, default, keys)
+          case default
+          when Array
+            value.respond_to?(:split) ? value.split(',') : Array(value)
+          when true, false
+            not FALSE.include?(value)
+          else
+            value
+          end
+        end
+
+        def namespace
+          Array(super && super.upcase)
+        end
+    end
+
+    attr_accessor :env_namespace
+
+    def defaults
+      Vars.new(super, env_namespace).to_h
+    end
+  end
+end

spec/hashr/env_spec.rb

@@ -0,0 +1,64 @@
+describe Hashr::Env do
+  let(:klass) do
+    Class.new(Hashr) do
+      extend Hashr::Env
+
+      self.env_namespace = 'hashr'
+
+      define string: 'string',
+             hash:   { key: 'value' },
+             array:  ['foo', 'bar'],
+             bool:   false
+    end
+  end
+
+  after do
+    ENV.keys.each { |key| ENV.delete(key) if key.start_with?('HASHR_') }
+  end
+
+  it 'defaults to an env var' do
+    ENV['HASHR_STRING'] = 'env string'
+    expect(klass.new.string).to eq('env string')
+  end
+
+  it 'defaults to a nested env var' do
+    ENV['HASHR_HASH_KEY'] = 'env value'
+    expect(klass.new.hash.key).to eq('env value')
+  end
+
+  describe 'type casts based on the default' do
+    describe 'to boolean' do
+      it 'true given' do
+        ENV['HASHR_BOOL'] = 'true'
+        expect(klass.new.bool).to eq(true)
+      end
+
+      it 'false given' do
+        ENV['HASHR_BOOL'] = 'false'
+        expect(klass.new.bool).to eq(false)
+      end
+
+      it 'empty string given' do
+        ENV['HASHR_BOOL'] = ''
+        expect(klass.new.bool).to eq(false)
+      end
+    end
+
+    describe 'to an array' do
+      it 'splits a comma-separated string' do
+        ENV['HASHR_ARRAY'] = 'env foo,env bar'
+        expect(klass.new.array).to eq(['env foo', 'env bar'])
+      end
+
+      it 'returns an empty array for an empty string' do
+        ENV['HASHR_ARRAY'] = ''
+        expect(klass.new.array).to eq([])
+      end
+    end
+  end
+
+  it 'data takes precedence over an env var' do
+    ENV['HASHR_STRING'] = 'env string'
+    expect(klass.new(string: 'data string').string).to eq('data string')
+  end
+end