desktop: use appstreamcli for testing instead of appstream-util.

As told to us, this is the reference AppStream file testing tool, and it
understands more of the spec.

Also since commit 73e2e701da, appstream-util chokes on newer url types
from the spec. These tags are now supported both in appstream-util and
appstreamcli source code, except that appstreamcli had release 0.15.3,
available in Debian testing, whereas there were apparently no recent
appstream-glib/util release (and none since 2020). So for these various
reasons, let's go with the appstreamcli tool.

The only downside is that appstream package (where appstreamcli lives)
is not available on MSYS2, but since it's only an optional test tool for
XML files which should be common on all platforms, it's probably
acceptable.

configure.ac

@@ -2656,24 +2656,24 @@ if test "x$with_xvfb_run" != "xno"; then
 fi
 AM_CONDITIONAL(HAVE_XVFB_RUN, test "x$have_xvfb_run" = "xyes")
 
-##########################
-# Check for appstream-util
-##########################
+########################
+# Check for appstreamcli
+########################
 
 AC_ARG_WITH(appdata-test,  [  --without-appdata-test  do not validate the appdata file])
 
-have_appstream_util="no (disabled)"
+have_appstreamcli="no (disabled)"
 if test "x$with_appdata_test" != "xno"; then
-  AC_PATH_PROG(APPSTREAM_UTIL, appstream-util, no)
+  AC_PATH_PROG(APPSTREAM_UTIL, appstreamcli, no)
   if test "x$APPSTREAM_UTIL" != "xno"; then
-    have_appstream_util="yes"
+    have_appstreamcli="yes"
   else
-    have_appstream_util="no (appstream-util not found)"
+    have_appstreamcli="no (appstreamcli not found)"
   fi
 fi
-AM_CONDITIONAL(HAVE_APPSTREAM_UTIL, test "x$have_appstream_util" = "xyes")
-if test "x$have_appstream_util" = "xyes"; then
-  have_appstream_util="yes (this test requires network access; --without-appdata-test to disable)"
+AM_CONDITIONAL(HAVE_APPSTREAM_UTIL, test "x$have_appstreamcli" = "xyes")
+if test "x$have_appstreamcli" = "xyes"; then
+  have_appstreamcli="yes (this test requires network access; --without-appdata-test to disable)"
 fi
 
 
@@ -3321,7 +3321,7 @@ Optional Modules:
 
 Tests:
   Use xvfb-run               $have_xvfb_run
-  Test appdata               $have_appstream_util
+  Test appdata               $have_appstreamcli
   Test desktop file          $have_desktop_file_validate
 
 Documentation:

desktop/meson.build

@@ -101,10 +101,10 @@ if desktop_validate.found()
   )
 endif
 
-if appstream_util.found()
+if appstreamcli.found()
   test('appdata_file',
-    appstream_util,
-    args: [ 'validate-relax', appdatafile ],
+    appstreamcli,
+    args: [ 'validate', appdatafile ],
     env: [
       'GIMP_TESTING_ABS_TOP_BUILDDIR=' + meson.build_root(),
     ],
@@ -112,8 +112,8 @@ if appstream_util.found()
   )
 
   test('metainfo_file',
-    appstream_util,
-    args: [ 'validate-relax', metainfofile ],
+    appstreamcli,
+    args: [ 'validate', metainfofile ],
     env: [
       'GIMP_TESTING_ABS_TOP_BUILDDIR=' + meson.build_root(),
     ],

desktop/test-appdata.sh.in

@@ -2,8 +2,8 @@
 
 # TODO: use validate-strict when the last errors for a strict validation
 # are fixed.
-appstream-util validate-relax ${GIMP_TESTING_ABS_TOP_BUILDDIR}/desktop/org.gimp.GIMP.appdata.xml && \
-appstream-util validate-relax ${GIMP_TESTING_ABS_TOP_BUILDDIR}/desktop/gimp-data-extras.metainfo.xml && \
+appstreamcli validate ${GIMP_TESTING_ABS_TOP_BUILDDIR}/desktop/org.gimp.GIMP.appdata.xml && \
+appstreamcli validate ${GIMP_TESTING_ABS_TOP_BUILDDIR}/desktop/gimp-data-extras.metainfo.xml && \
 if [ $(expr @GIMP_MICRO_VERSION@ % 2) = 0 ]; then
   grep TODO ${GIMP_TESTING_ABS_TOP_BUILDDIR}/desktop/org.gimp.GIMP.appdata.xml
   if [ $? = 0 ]; then

meson.build

@@ -1020,7 +1020,7 @@ xsltproc            = find_program('xsltproc')
 intltool_merge      = find_program('intltool-merge')
 desktop_validate    = find_program('desktop-file-validate', required: false)
 
-appstream_util = find_program('appstream-util', required: get_option('appdata-test'))
+appstreamcli = find_program('appstreamcli', required: get_option('appdata-test'))
 
 # Check for doc generation tools
 
@@ -1863,7 +1863,7 @@ final_message = [
 '',
 '''Tests:''',
 '''  Use xvfb-run         @0@'''.format(xvfb_run.found()),
-'''  Test appdata         @0@'''.format(appstream_util.found()),
+'''  Test appdata         @0@'''.format(appstreamcli.found()),
 '',
 '''Documentation:''',
 '''  libgimp API Reference: @0@'''.format(gi_docgen.found()),