Make chromedriver headless mode optional

Related: #63

.gitlab-ci.yml

@@ -71,7 +71,7 @@ behave:
   script:
     # Run behave tests
     - cd test/behave/
-    - behave
+    - behave -D headless=True
   artifacts:
     paths:
     - test/behave/screenshots/

test/behave/features/environment.py

@@ -28,8 +28,11 @@ def before_all(context):
     context.keycloak['admin']['username'] = userdata.get('keycloak.admin.username')
     context.keycloak['admin']['password'] = userdata.get('keycloak.admin.password')
 
+    headless = userdata.get('headless', 'False')
+
     chrome_options = ChromeOptions()
-    chrome_options.add_argument('--headless')
+    if headless == 'True':
+        chrome_options.add_argument('--headless')
     chrome_options.add_argument('--no-sandbox')
     chrome_options.add_argument('--disable-dev-shm-usage')
     context.behave_driver = behave_webdriver.Chrome(