Use distincts env

.gitlab-ci.yml

@@ -3,22 +3,33 @@ image: jekyll/minimal:3.8
 variables:
   LC_ALL: C.UTF-8
 
-test:
-  stage: test
+dev:
+  stage: build
   script:
-  - jekyll build -d test
+  - jekyll build --config _config.yml,_config_dev.yml
   artifacts:
     paths:
-    - test
+    - _site
   except:
   - master
+  - dev
+
+test:
+  stage: build
+  script:
+  - jekyll build --config _config.yml,_config_test.yml
+  artifacts:
+    paths:
+    - _site
+  only:
+  - dev
 
 www:
-  stage: deploy
+  stage: build
   script:
-  - jekyll build -d public
+  - jekyll build
   artifacts:
     paths:
-    - public
+    - _site
   only:
   - master

_config_dev.yml

+# The base hostname & protocol for your site without a trailing slash.
+url: "http://localhost"

_config_test.yml

+# The base hostname & protocol for your site without a trailing slash.
+url: "https://test.orekit.org"