Allow a custom environment variable prefix to include the environment variable separator

lib/config/options.rb

@@ -37,9 +37,12 @@ def reload_env!
       hash = Hash.new
 
       ENV.each do |variable, value|
-        keys = variable.to_s.split(Config.env_separator)
+        separator = Config.env_separator
+        prefix = (Config.env_prefix || Config.const_name).to_s.split(separator)
 
-        next if keys.shift != (Config.env_prefix || Config.const_name)
+        keys = variable.to_s.split(separator)
+
+        next if keys.shift(prefix.size) != prefix
 
         keys.map! { |key|
           case Config.env_converter

spec/config_env_spec.rb

@@ -126,6 +126,45 @@
       end
     end
 
+    context 'and custom ENV variables prefix includes custom ENV variables separator' do
+      before :each do
+        Config.env_prefix = 'MY_CONFIG'
+        Config.env_separator = '_'
+      end
+
+      it 'should load environment variables which begin with the custom prefix' do
+        ENV['MY_CONFIG_KEY'] = 'value'
+
+        expect(config.key).to eq('value')
+      end
+
+      it 'should not load environment variables which begin with the default prefix' do
+        ENV['Settings_key'] = 'value'
+
+        expect(config.key).to eq(nil)
+      end
+
+      it 'should not load environment variables which partially begin with the custom prefix' do
+        ENV['MY_CONFIGS_KEY'] = 'value'
+
+        expect(config.key).to eq(nil)
+      end
+
+      it 'should recognize the custom separator' do
+        ENV['MY_CONFIG_KEY.WITH.DOT']           = 'value'
+        ENV['MY_CONFIG_WORLD_COUNTRIES_EUROPE'] = '0'
+
+        expect(config['key.with.dot']).to eq('value')
+        expect(config.world.countries.europe).to eq(0)
+      end
+
+      it 'should not recognize the default separator' do
+        ENV['MY_CONFIG.KEY'] = 'value'
+
+        expect(config.key).to eq(nil)
+      end
+    end
+
     context 'and variable names conversion is enabled' do
       it 'should downcase variable names when :downcase conversion enabled' do
         ENV['Settings.NEW_VAR'] = 'value'