[mutter] ci: Enable coverage report using cobertura format

[Marge Bot <marge-bot src gnome org>]

commit 0a234f320b3492cc8deb17aac71788bec272ec29
Author: Marco Trevisan (Treviño) <mail 3v1n0 net>
Date:   Thu Jul 21 01:28:53 2022 +0200

    ci: Enable coverage report using cobertura format
    
    This will allow to integrate coverage information with MR's diffs.
    
    See https://docs.gitlab.com/ee/ci/testing/test_coverage_visualization.html
    
    Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2515>

 .gitlab-ci.yml | 9 +++++++++
 1 file changed, 9 insertions(+)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 8116bb5d84..c24c5268f8 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -421,11 +421,20 @@ coverage:
     - mkdir coveragereport
     - gcovr --add-tracefile 'coverage-*.json'
         --html-details --print-summary --output coveragereport/index.html
+    - gcovr --add-tracefile 'coverage-*.json'
+        --xml --output coveragereport/coverage.xml
   artifacts:
     expose_as: 'Coverage Report'
     paths:
       - coveragereport
       - coveragereport/index.html
+    reports:
+      coverage_report:
+        coverage_format: cobertura
+        # TODO: we may need to split this file once it will reach the
+        # gitlab limit size of 10M, or it will stop working:
+        #  https://gitlab.com/gitlab-org/gitlab/-/issues/328772
+        path: coveragereport/coverage.xml
   coverage: '/^lines: (\d+\.\d+\%)/'
   needs:
     - test-mutter@x86_64