ci: Add test stage

We never gained a proper test suite, but run at least the tests we
have.

https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/408

.gitlab-ci.yml

@@ -2,6 +2,7 @@ stages:
  - review
  - source_check
  - build
+ - test
 
 variables:
     JS_LOG: "js-report.txt"
@@ -51,3 +52,22 @@ build:
         - ninja -C build
         - ninja -C build install
     <<: *only_default
+    artifacts:
+        expire_in: 1 day
+        paths:
+            - mutter
+            - build
+
+test:
+    image: registry.gitlab.gnome.org/gnome/gnome-shell/master:v1
+    stage: test
+    before_script:
+        - ninja -C mutter/build install
+    script:
+        - xvfb-run meson test -C build --no-rebuild
+    <<: *only_default
+    artifacts:
+        expire_in: 1 day
+        paths:
+            - build/meson-logs/testlog.txt
+        when: on_failure