Some tests output:
WARN [Nuxeo-Work-default-3:test:424dfeaa-5e3a-441a-90df-07a3dd3f89a2:sqlFulltextExtractor] [FulltextExtractorWork] Could not extract fulltext of file 'test.pdf' for document: 424dfeaa-5e3a-441a-90df-07a3dd3f89a2: org.nuxeo.ecm.core.convert.api.ConversionException: Error while converting via CommandLineService
This is because we create a PDF file that doesn't actually contain a valid PDF, so the fulltext extractor has a problem with it.