diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index e5384a8cf9d2743a1ddee2df1f7ed5d3631399a1..1a2610504be961ebd231dd53ed51b7f0dd71434a 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -18,12 +18,26 @@ include:
       - "/includes/include.drupalci.variables.yml"
       - "/includes/include.drupalci.workflows.yml"
 
+# Require optional CI tests to pass.
+composer-lint:
+  allow_failure: false
+cspell:
+  allow_failure: false
+eslint:
+  allow_failure: false
+phpcs:
+  allow_failure: false
+phpstan:
+  allow_failure: false
+
 ################
 # Pipeline configuration variables are defined with default values and descriptions in the file
 # https://git.drupalcode.org/project/gitlab_templates/-/blob/main/includes/include.drupalci.variables.yml
 # Uncomment the lines below if you want to override any of the variables. The following is just an example.
 ################
-# variables:
+variables:
+  OPT_IN_TEST_MAX_PHP: '1'
+  OPT_IN_TEST_PREVIOUS_MAJOR: '1'
 #   SKIP_ESLINT: '1'
 #   OPT_IN_TEST_NEXT_MAJOR: '1'
 #   _CURL_TEMPLATES_REF: 'main'