When testing the latest trimmomatic tool (from https://github.com/fls-bioinformatics-core/galaxy-tools/tree/master/trimmomatic, planemo test reports an error on the last test, but according to the test report the test has succeeded (see attached HTML and JSON). For the test setup you need to set some environment variables:
TRIMMOMATIC_DIR - the location of the trimmomatic jar
TRIMMOMATIC_JAR - the name of the jar file
TRIMMOMATIC_ADAPTERS_DIR - location of adapters
This is with planemo 0.22.2 and a fresh $HOME/.planemo.