How to debug jQassistant in eclipse

Question

I want to understand the scanning process of jqassistant in detail. For example will it scan all Jar-Files and all classes or only the one I directly reference from my classes. To answer such questions debugging is often a good option. How ever normally you start jqassistant as maven plugin. Debug maven plugin is not so easy. So I thought it's better to checkout the commandline-client. Debugging works fine, but unfortunately I get a complete different result. Here are my parameter scan --files ${project_loc:/sze}/target/classes,${project_loc:/sze}/target/test-classes --storeDirectory c:/trash/neo4j. The output is the same as in the maven-build it scans 441 and then 106 classes.

Can anyone give me a hint, what's wrong with the commandline-call? Or what whould be the best solution to answer the question from the beginning.

Answer 1

I think the best option is to debug the maven-plugin, because then all configuration and classpath-problems are solved. This isn't as complicated as I thought. The following step solve my problems:

1. clone the project git clone https://github.com/buschmais/jqa-maven-plugin.git and checkout a stable version, for example git checkout -b 1.2.0
2. Import jqassistant-maven-plugin into your eclipse workspace.
3. Prepare your maven-run-configuration and add -Xdebug -Xnoagent -Djava.compile=NONE -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=5005 as VM-Arguments.
4. Create a debug-configuration for Remote Java Application and choose as Project jqassistant-maven-plugin. Set Connection Properties to localhost and 5005
5. Set a breakpoint in ScannerImpl in methode scan. Further good candidates are the ClassFileScannerPlugin and ClassVisitor.
6. Start the maven run configuration and then start the debug-configuration.

Now you can easily debug the code. Unfortunately many visitor patterns makes it difficult to understand how it works.

Based on my analysis I can say, that only file in classes and test-classes are analyzed. All classes from library only come into the database via reference. I guess that the org.objectweb.asm.ClassReader doesn't simply ignores references which are not in the classpath. This is the reason why the command line version doesn't find so much elements.