Jacoco Agent - Get Method Coverage from Jacoco Exec file

[wwaylo...@gmail.com]

Hi,

I'm using Jacoco as a Java agent to instrument classes to obtain coverage information. Currently, I can get the probe hit count of a given class. I followed the example from https://www.eclemma.org/jacoco/trunk/doc/examples/java/ExecDump.java to retrieve the number of probes hit for each class as recorded in a specified .exec file.

However, how can I get a finer granularity coverage report, specifically one that includes method information? Is it possible to associate the probe array with a set of methods?

I am able to get this information if I don't use Jacoco as a Java agent and make calls directly to the Jacoco.core.analysis package. However, if I need to use Jacoco as a Java agent, how could I get this same information?

Thank you!

[wwaylo...@gmail.com]

I'm wondering if it's possible to instrument the classes by using Jacoco as a java agent but also collect the coverage information many times during run time by using an Analyzer instance?

[Marc Hoffmann]

Hi,

code coverage analysis with JaCoCo is a two step process:

1) Collect execution data at runtime (typically with the JaCoCo agent)
2) Create a detailed report (with the analyzer API or any of our tool
integrations like Ant, Maven, CLI, ...)

Regards,
-marc

[Marc Hoffmann]

The JaCoCo agent offers remote APIs (TCP socket, JMX) as well as a
runtime API:

https://www.jacoco.org/jacoco/trunk/doc/api/org/jacoco/agent/rt/package-summary.html

So yes, you could collect multiple dumps during execution and perform
analysis on it. E.g. with our Eclipse integration EclEmma this is
possible. You can dump execution data at any point in time while a
program is running:

https://www.eclemma.org/userdoc/coverageview.html

Regards,
-marc

[wwaylo...@gmail.com]

Hi Marc!

Thank you for the reply!

The runtime API looks promising. It appears I can retrieve the IAgent instance and call getExecutionData().

However, that returns a byte array. To what could I pass this byte array to, to start analyzing the data and retrieving method coverage information?

Thank you!

[Marc Hoffmann]

The byte array is the content of the exec file that would be written.
With

new java.io.ByteArrayInputStream(array)

you can easily convert it to an InputStream that can be read by the
JaCoCo APIs.

Regards,
-marc