Question

I have a project with Maven build and need to add some basic performance tracing to methods. I decided to use AspectJ for this. Main requirement is to weave tracing aspect into production classes but only for unit tests execution phase.

I was able to configure weaving in Maven however after execution of tests same production classes with aspect applied go to packaged war.

The case looks like pretty common nevertheless I wasn’t able to find solution for it in web.

Answer 1

I would do that in a dedicated module, use the Maven Dependency Plugin to unpack the artifact “under test” during the generate-test-sources phase, then weave the classes and finally run the tests.

---

Let me try to illustrate what I mean. Let’s imagine the following project structure:

.
|-- pom.xml
`-- some-module    // this is the module that we want to weave 
    |-- pom.xml    // but only for testing purpose
    `-- ...

So my suggestion is to do something like this:

.
|-- pom.xml
|-- some-module      
|   |-- pom.xml      
|   `-- ...
`-- test-module    // we're going to weave the classes here because we don't want
    |-- pom.xml    // the tracing aspect to be packaged in the "production" jar
    `-- ...

The idea is to have an additional “test-module” where we would unpack the artifact that we want to test so that we can weave its classes without affecting the “real” production jar.

To do so, declare a dependency on the module under test and use dependency:unpack to unpack the classes into target/classes before invoking the AspectJ plugin to weave the “main” classes.