1 files changed, 23 insertions, 0 deletions
diff --git a/spec/lib/gitlab/ci/config/interpolation/functions/base_spec.rb b/spec/lib/gitlab/ci/config/interpolation/functions/base_spec.rb
new file mode 100644
index 00000000000..c193e88dbe2
--- /dev/null
+++ b/spec/lib/gitlab/ci/config/interpolation/functions/base_spec.rb
@@ -0,0 +1,23 @@
+# frozen_string_literal: true
+
+require 'fast_spec_helper'
+
+RSpec.describe Gitlab::Ci::Config::Interpolation::Functions::Base, feature_category: :pipeline_composition do
+  let(:custom_function_klass) do
+    Class.new(described_class) do
+      def self.function_expression_pattern
+        /.*/
+      end
+
+      def self.name
+        'test_function'
+      end
+    end
+  end
+
+  it 'defines an expected interface for child classes' do
+    expect { described_class.function_expression_pattern }.to raise_error(NotImplementedError)
+    expect { described_class.name }.to raise_error(NotImplementedError)
+    expect { custom_function_klass.new('test').execute('input') }.to raise_error(NotImplementedError)
+  end
+end