ci: Test metainfo when it changes

Avoids bad surprises with Flathub after a release is tagged.

.gitlab-ci.yml

@@ -20,6 +20,9 @@ include:
   - local: .gitlab-ci/build.yml
     rules:
       - if: $CI_COMMIT_TAG == null
+  - local: .gitlab-ci/test.yml
+    rules:
+      - if: $CI_COMMIT_TAG == null
   - local: .gitlab-ci/publish_docs.yml
     rules:
       - if: $CI_COMMIT_BRANCH == "main"

.gitlab-ci/build.yml

@@ -10,6 +10,14 @@ build@x86_64:
   extends:
     - .flatpak@x86_64
   stage: build
+  artifacts:
+    paths:
+      - $BUNDLE
+      - 'repo.tar'
+      - '.flatpak-builder/build/${FLATPAK_MODULE}/_flatpak_build/meson-logs/meson-log.txt'
+      - '.flatpak-builder/build/${FLATPAK_MODULE}/_flatpak_build/meson-logs/testlog.txt'
+      # Add the metainfo file for the corresponding test.
+      - '.flatpak-builder/build/${FLATPAK_MODULE}/_flatpak_build/data/${APP_ID}.metainfo.xml'
 
 build@aarch64:
   extends:

.gitlab-ci/test.yml

@@ -0,0 +1,21 @@
+# Tests after the app is built.
+
+# Validate the metainfo with Flathub's tool.
+metainfo:
+  stage: test
+  image:
+    name: "ghcr.io/flathub/flatpak-builder-lint:latest"
+    entrypoint: [""]
+  variables:
+    METAINFO: ".flatpak-builder/build/${FLATPAK_MODULE}/_flatpak_build/data/${APP_ID}.metainfo.xml"
+  script:
+    # This tool has extra tests on top of appstreamcli and is required to pass for Flathub.
+    - flatpak-builder-lint appstream ${METAINFO}
+    # Test also with the pedantic and strict flags.
+    - appstreamcli validate --pedantic --explain --strict ${METAINFO}
+  needs: ["build@x86_64"]
+  rules:
+    - changes:
+        - data/org.gnome.Fractal.metainfo.xml.in.in
+      when: always
+    - when: manual