add a way to handle env checks using method names

cleanup the method missing magic for enviroment test

ammend space

add a comment to the variable place

Fixes #2356

lib/logstash/environment.rb

@@ -39,6 +39,18 @@ module LogStash
       LOGSTASH_ENV
     end
 
+    def production?
+      env.downcase == "production"
+    end
+
+    def development?
+      env.downcase == "development"
+    end
+
+    def test?
+      env.downcase == "test"
+    end
+
     # set GEM_PATH for logstash runtime
     # GEM_PATH should include the logstash gems, the plugin gems and the bootstrap gems.
     # the bootstrap gems are required specificly for bundler which is a runtime dependency

lib/logstash/pluginmanager/install.rb

@@ -56,7 +56,9 @@ class LogStash::PluginManager::Install < Clamp::Command
     FileDependencies::Gem.hook
     options = {}
     options[:document] = []
-    if  LogStash::Environment.env == 'test'
+    if LogStash::Environment.test?
+      # More info on what do this options means
+      # https://github.com/rubygems/rubygems/blob/master/lib/rubygems/dependency_installer.rb#L56
       options[:dev_shallow] = true
       options[:development] = true
     end