No error output with -a ebook-validate

[tombentley]

I'm running asciidoctor-epub3 in a container and while an epub output is created, if I try to validate it I'm told validation failed with no further diagnostics about what was wrong.

Command: asciidoctor-epub3 -D output -R src -a ebook-validate --verbose src/master-epub.adoc

Output:

asciidoctor: DEBUG: Wrote EPUB3 to /build/output/master-epub.epub
asciidoctor: DEBUG: Using EPUBCheck from gem: /usr/lib/ruby/gems/2.7.0/gems/epubcheck-ruby-4.2.5.0/exe/epubcheck
asciidoctor: ERROR: EPUB validation failed: /build/output/master-epub.epub

[slonopotamus]

Most likely cause is that you don't have java on PATH.

[tombentley]

That was indeed the problem, thanks! It's not mentioned that java is a runtime dependency in the docs though: https://docs.asciidoctor.org/epub3-converter/latest/

[slonopotamus]

Reported upstream: takahashim/epubcheck-ruby#18

[slonopotamus]

Docs don't even say that you should install epubcheck-ruby to get epubcheck :) I'll improve the docs and close this issue then.

[tombentley]

Great, thanks!