travis-ci: build documentation with AsciiDoc and Asciidoctor

ec3366e introduced a knob to enable the use of Asciidoctor in addition
to AsciiDoc. Build the documentation on TravisCI with this knob to
reduce the likeliness of breaking Asciidoctor support in the future.

Signed-off-by: Lars Schneider <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: larsxschneider

.travis.yml

@@ -69,7 +69,7 @@ matrix:
           - asciidoc
           - xmlto
       before_install:
-      before_script:
+      before_script: gem install asciidoctor
       script: ci/test-documentation.sh
       after_failure:
 

ci/test-documentation.sh

@@ -7,8 +7,16 @@ set -e
 
 make check-builtins
 make check-docs
-make doc
 
+# Build docs with AsciiDoc
+make doc
 test -s Documentation/git.html
 test -s Documentation/git.xml
 test -s Documentation/git.1
+grep '<meta name="generator" content="AsciiDoc ' Documentation/git.html
+
+# Build docs with AsciiDoctor
+make clean
+make USE_ASCIIDOCTOR=1 doc
+test -s Documentation/git.html
+grep '<meta name="generator" content="Asciidoctor ' Documentation/git.html