diff --git a/.devtools/assemble.sh b/.devtools/assemble.sh
index a23bff5..4bdb3ee 100755
--- a/.devtools/assemble.sh
+++ b/.devtools/assemble.sh
@@ -122,8 +122,6 @@ fi
 sed "${sed_opts[@]}" 's|\(.*"prefer-stable"\): \(.*\),.*|\1: '${drupal_version_prefer_stable}',|' "build/composer.json"
 grep 'prefer-stable' "build/composer.json"
 
-pass "Drupal codebase created."
-
 info "Merging configuration from composer.dev.json."
 php -r "echo json_encode(array_replace_recursive(json_decode(file_get_contents('composer.dev.json'), true),json_decode(file_get_contents('build/composer.json'), true)),JSON_PRETTY_PRINT|JSON_UNESCAPED_SLASHES);" >"build/composer2.json" && mv -f "build/composer2.json" "build/composer.json"
 
diff --git a/.scaffold/tests/bats/functional.assemble.bats b/.scaffold/tests/bats/functional.assemble.bats
new file mode 100644
index 0000000..97b6a9d
--- /dev/null
+++ b/.scaffold/tests/bats/functional.assemble.bats
@@ -0,0 +1,39 @@
+#!/usr/bin/env bats
+
+load _helper
+
+export BATS_FIXTURE_EXPORT_CODEBASE_ENABLED=1
+
+@test "Assemble: Drupal 11" {
+  run .devtools/assemble.sh
+  assert_success
+
+  assert_output_contains "Initialising Drupal 11 site"
+
+  assert_output_contains "ASSEMBLE COMPLETE"
+  assert_dir_exists "${BUILD_DIR}/build/vendor"
+  assert_file_exists "${BUILD_DIR}/build/composer.json"
+  assert_file_exists "${BUILD_DIR}/build/composer.lock"
+
+  # @see https://github.com/composer/composer/issues/12215
+  run composer --working-dir="${BUILD_DIR}/build" require --dev drupal/coder --with-all-dependencies --dry-run
+  assert_output_not_contains "Upgrading"
+}
+
+@test "Assemble: Drupal 10" {
+  export DRUPAL_VERSION="10"
+
+  run .devtools/assemble.sh
+  assert_success
+
+  assert_output_contains "Initialising Drupal 10 site"
+
+  assert_output_contains "ASSEMBLE COMPLETE"
+  assert_dir_exists "${BUILD_DIR}/build/vendor"
+  assert_file_exists "${BUILD_DIR}/build/composer.json"
+  assert_file_exists "${BUILD_DIR}/build/composer.lock"
+
+  # @see https://github.com/composer/composer/issues/12215
+  run composer --working-dir="${BUILD_DIR}/build" require --dev drupal/coder --with-all-dependencies --dry-run
+  assert_output_not_contains "Upgrading"
+}
diff --git a/composer.dev.json b/composer.dev.json
index 84ae244..fbe3475 100644
--- a/composer.dev.json
+++ b/composer.dev.json
@@ -6,6 +6,7 @@
         "palantirnet/drupal-rector": "^0.18",
         "phpcompatibility/php-compatibility": "^9.3",
         "phpmd/phpmd": "^2.15",
+        "phpstan/phpdoc-parser": "^1",
         "phpspec/prophecy-phpunit": "^2",
         "phpstan/extension-installer": "^1.3",
         "vincentlanglet/twig-cs-fixer": "^2.8"