create a class to hold the plugin version

Fixes #2331

lib/logstash/config/mixin.rb

@@ -6,6 +6,8 @@ require "logstash/logging"
 require "logstash/util/password"
 require "logstash/version"
 require "logstash/environment"
+require "logstash/util/plugin_version"
+
 LogStash::Environment.load_locale!
 
 # This module is meant as a mixin to classes wishing to be configurable from
@@ -212,11 +214,7 @@ module LogStash::Config::Mixin
       specification = Gem::Specification.find_by_name(plugin_gem_name)
       major, minor, patch = specification.version.segments
 
-      return {
-        :major => major,
-        :minor => minor,
-        :patch => patch 
-      }
+      return LogStash::Util::PluginVersion.new(major, minor, patch)
     end
 
     def plugin_gem_name
@@ -226,8 +224,8 @@ module LogStash::Config::Mixin
     def print_version_notice
       return true if @@version_notice_given
 
-      if plugin_version[:major] < 1
-        if plugin_version[:minor] == 9
+      if plugin_version.major < 1
+        if plugin_version.minor == 9
           @logger.warn(I18n.t("logstash.plugin.version.0-9-x", 
                               :type => @plugin_type,
                               :name => @config_name,

lib/logstash/util/plugin_version.rb

@@ -0,0 +1 @@
+LogStash::Util::PluginVersion = Struct.new(:major, :minor, :patch)

spec/core/plugin_spec.rb

@@ -69,7 +69,7 @@ describe LogStash::Plugin do
     end
 
     it "doesnt show the version notice more than once" do
-      class LogStash::Filters::Stromae < LogStash::Filters::Base
+      one_notice = Class.new(LogStash::Filters::Base) do
         config_name "stromae"
       end
 
@@ -81,8 +81,8 @@ describe LogStash::Plugin do
         .once
         .with(/Using version 0.1.x/)
 
-      LogStash::Filters::Stromae.validate({})
-      LogStash::Filters::Stromae.validate({})
+      one_notice.validate({})
+      one_notice.validate({})
     end
 
     it 'logs an error if the plugin use the milestone option' do

spec/util/plugin_version_spec.rb

@@ -0,0 +1,13 @@
+require "logstash/util/plugin_version"
+
+describe LogStash::Util::PluginVersion do
+  subject { LogStash::Util::PluginVersion }
+
+  it 'contains the semver parts of a plugin version' do
+    version = subject.new(1, 2, 3)
+
+    expect(version.major).to eq(1)
+    expect(version.minor).to eq(2)
+    expect(version.patch).to eq(3)
+  end
+end