updated the plugin manager install process to request to install the plugin development dependencies whenever an env variable is properly set to test, like this we can run test from logstash if necessary

renamed the LOGSTASH_ENV var to follow the LS_ENV standard

Fixes #2356

lib/logstash/environment.rb

@@ -12,6 +12,8 @@ module LogStash
     GEMFILE_PATH = ::File.join(LOGSTASH_HOME, "tools", "Gemfile")
     BOOTSTRAP_GEM_PATH = ::File.join(LOGSTASH_HOME, 'build', 'bootstrap')
 
+    LOGSTASH_ENV = (ENV["LS_ENV"] || 'production').to_s.freeze
+
     # loads currently embedded elasticsearch jars
     # @raise LogStash::EnvironmentError if not running under JRuby or if no jar files are found
     def load_elasticsearch_jars!
@@ -33,6 +35,10 @@ module LogStash
       ::File.join(BUNDLE_DIR, ruby_engine, gem_ruby_version)
     end
 
+    def env
+      LOGSTASH_ENV
+    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

@@ -56,6 +56,10 @@ class LogStash::PluginManager::Install < Clamp::Command
     FileDependencies::Gem.hook
     options = {}
     options[:document] = []
+    if  LogStash::Environment.env == 'test'
+      options[:dev_shallow] = true
+      options[:development] = true
+    end
     inst = Gem::DependencyInstaller.new(options)
     inst.install plugin, version
     specs = inst.installed_gems.detect { |gemspec| gemspec.name == gem_meta.name }