ci: add test job for building the docker image

.gitlab-ci.yml

@@ -29,6 +29,21 @@ test:
   tags:
     - docker
 
+test:image-build:
+  image: registry.gitlab.com/openstapps/projectmanagement/builder
+  stage: test
+  dependencies:
+    - build
+  variables:
+    DOCKER_DRIVER: overlay2
+  services:
+    - docker:dind
+  script:
+    - docker login -u gitlab-ci-token -p $CI_BUILD_TOKEN $CI_REGISTRY
+    - docker build -t $CI_REGISTRY_IMAGE/$REGISTRY_BRANCH$CI_COMMIT_REF_NAME:latest .
+  tags:
+    - docker
+
 publish:
   image: registry.gitlab.com/openstapps/projectmanagement/builder
   stage: publish