Aggregating JUnit test results from multiple projects
The JUNIT plugin has a built-in publisher for aggregating test results called "Aggregate Downstream Test Results". You need to make sure that the 'parent' and 'child' jobs are linked together with a downstream/upstream relation. This is usually done by archiving an artifact in the parent build and copying it to the children builds using the 'Archive Artifact' publisher and the 'Copy Artifact' buildstep respectively.