Jython for Robotframework EDitor

Setup of Jython for RED, the Robot Framework editor for Eclipse

Introduction

When you use RED, you can use Python with Robot Framework and all its installed libraries (Selenium for instance) to launch tests. However, if you use Maven and thus the Maven Robot Framework plugin, you risk to use a different Robot Framework version with RED than you use with Maven. Plus, the Python variant in RED cannot use Java libraries like the Maven variant does (which is based on Jython). You may use Jython of course but the last versions 2.7.0 and 2.7.1 did not run well on my Windows 7 laptop due to Pip and DLL problems respectively. And Jython seems to be not so well supported as Python is.

But there seemed to be a solution, How to integrate RED with Robotframework Maven Plugin, that describes a way to use the same Robot Framework jar as Maven does. In that solution the launch4j program is used to create a Jython executable based on the Robot Framework Jar (which includes Jython as well). There are a few snags however as I discovered when I tried to use that approach.

This Blog is written for a Windows environment (it has been tested on Windows 7 and Windows 10), but it might also work on a Unix like environment.

Problems encountered

Classpath entries

First, you have to hard code your Jar libraries as Java classpath entries into the launch4j configuration file. That means that if you need a new Jar library you would need to recreate the Jython executable. And I needed not only Robot Framework, Selenium but also a JDBC database library and a JMS library. And other projects may have other constraints. Actually what you would like to use is the compile classpath of Maven which is a complete list of jars and its dependencies.

Jython arguments

The second problem was that RED launches the generated Jython program with arguments not recognized by the robotframework.jar (for instance -J-cp <classpath>) or with arguments just applicable for a Java interpreter like -Dvar=value.

Java version

The third and last problem was that launch4j searches the Java executable a little bit too sophisticated (or complicated): it uses the Windows registry to look for a system-wide installed JRE/JDK with a minimum and/or maximum version. On the Windows 7 system I was using, only Java 1.7 was installed system-wide and I had no privileges to install a higher version. And the Selenium library really needed Java 1.8. I was stuck.

A workaround

So what to do?

The first and second problem are actually environment problems. I need another program to set up an environment (for instance set environment variables, determine the Maven classpath and change the command line) before launching the robotframework.jar with arguments it recognizes. My old friend, script language Perl, came to my rescue. The Windows variant Strawberry Perl allows you to create executables based on Perl scripts using the Perl CPAN module Par::packer.

So the idea is to create an executable named Jython (jython.exe) that is called from the Eclipse RED editor and that sets up the environment before launching Java with the robotframework.jar.

All the build steps must be automated as well of course and what is more easy to use than good old Ant? I really have no idea.

Installation

See the installation manual.