ci: perform build and smoke tests for Meson docs

Our "documentation" CI job performs a couple of tests against our
documentation. Part of these tests is to check whether documentation
builds at all and whether it spits out the expected set of files. We
don't yet have such a test for Meson, which means that we wouldn't
notice at all if building the documentation were to break. As a result,
breakages as fixed by 87eccc3a81 (meson: fix building technical and
howto docs, 2025-03-02) are easy to go unnoticed.

Address this test gap by starting to build both manpages and HTML sites
as part of the CI job.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

ci/test-documentation.sh

@@ -15,6 +15,13 @@ filter_log () {
 	    "$1"
 }
 
+check_docs () {
+	test -s "$1"/Documentation/git.html &&
+	test -s "$1"/Documentation/git.xml &&
+	test -s "$1"/Documentation/git.1 &&
+	grep "<meta name=\"generator\" content=\"$2 " "$1"/Documentation/git.html
+}
+
 make check-builtins
 make check-docs
 
@@ -23,10 +30,7 @@ make doc > >(tee stdout.log) 2> >(tee stderr.raw >&2)
 cat stderr.raw
 filter_log stderr.raw >stderr.log
 test ! -s stderr.log
-test -s Documentation/git.html
-test -s Documentation/git.xml
-test -s Documentation/git.1
-grep '<meta name="generator" content="AsciiDoc ' Documentation/git.html
+check_docs . AsciiDoc
 
 rm -f stdout.log stderr.log stderr.raw
 check_unignored_build_artifacts
@@ -37,10 +41,21 @@ make USE_ASCIIDOCTOR=1 doc > >(tee stdout.log) 2> >(tee stderr.raw >&2)
 cat stderr.raw
 filter_log stderr.raw >stderr.log
 test ! -s stderr.log
-test -s Documentation/git.html
-grep '<meta name="generator" content="Asciidoctor ' Documentation/git.html
+check_docs . Asciidoctor
 
 rm -f stdout.log stderr.log stderr.raw
 check_unignored_build_artifacts
 
+# Build docs with Meson and AsciiDoc
+meson setup build-asciidoc -Ddocs=html,man -Ddocs_backend=asciidoc
+meson compile -C build-asciidoc
+check_docs build-asciidoc AsciiDoc
+rm -rf build-asciidoc
+
+# Build docs with Meson and AsciiDoctor
+meson setup build-asciidoctor -Ddocs=html,man -Ddocs_backend=asciidoctor
+meson compile -C build-asciidoctor
+check_docs build-asciidoctor Asciidoctor
+rm -rf build-asciidoctor
+
 save_good_tree