add ci_test.bat file for windows testing (#7557)

this relies on jruby being installed locally with the same version as
the one contained in the .ruby-version file at the root of the project

The jruby must be installed in %JRUBYSRCDIR%\%JRUBYVERSION%

ci/ci_test.bat

@@ -0,0 +1,41 @@
+@echo off
+
+setlocal
+
+REM Since we are using the system jruby, we need to make sure our jvm process
+REM uses at least 1g of memory, If we don't do this we can get OOM issues when
+REM installing gems. See https://github.com/elastic/logstash/issues/5179
+
+SET JRUBY_OPTS="-J-Xmx1g"
+SET SELECTEDTESTSUITE=%1
+SET /p JRUBYVERSION=<.ruby-version
+
+IF NOT EXIST %JRUBYSRCDIR% (
+  echo "Variable JRUBYSRCDIR must be declared with a valid directory. Aborting.."
+  exit /B 1
+)
+
+SET JRUBYPATH=%JRUBYSRCDIR%\%JRUBYVERSION%
+
+IF NOT EXIST %JRUBYPATH% (
+  echo "Could not find JRuby in %JRUBYPATH%. Aborting.."
+  exit /B 1
+)
+
+SET RAKEPATH=%JRUBYPATH%\bin\rake
+
+IF "%SELECTEDTESTSUITE%"=="core-fail-fast" (
+  echo "Running core-fail-fast tests"
+  %RAKEPATH% test:install-core
+  %RAKEPATH% test:core-fail-fast
+) ELSE (
+  IF "%SELECTEDTESTSUITE%"=="all" (
+    echo "Running all plugins tests"
+    %RAKEPATH% test:install-all
+    %RAKEPATH% test:plugins
+  ) ELSE (
+    echo "Running core tests"
+    %RAKEPATH% test:install-core
+    %RAKEPATH% test:core
+  )
+)