Capture test results from JUnit output

.gitlab-ci.yml

@@ -14,7 +14,13 @@ before_script:
 spec:
   script:
     - shards
-    - crystal spec --error-on-warnings
+    - crystal spec --error-on-warnings --junit_output=.
+  artifacts:
+    when: always
+    paths:
+      - output.xml
+    reports:
+      junit: output.xml
 
 format:
   script:
@@ -31,8 +37,14 @@ nightly:
   allow_failure: true
   script:
     - shards --ignore-crystal-version
-    - crystal spec --error-on-warnings
+    - crystal spec --error-on-warnings --junit_output=.
     - crystal tool format --check
+  artifacts:
+    when: always
+    paths:
+      - output.xml
+    reports:
+      junit: output.xml
 
 pages:
   stage: deploy