1 files changed, 44 insertions, 0 deletions
diff --git a/lib/gitlab/ci/input/arguments/default.rb b/lib/gitlab/ci/input/arguments/default.rb
new file mode 100644
index 00000000000..fd61c1ab786
--- /dev/null
+++ b/lib/gitlab/ci/input/arguments/default.rb
@@ -0,0 +1,44 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Ci
+    module Input
+      module Arguments
+        ##
+        # Input::Arguments::Default class represents user-provided input argument that has a default value.
+        #
+        class Default < Input::Arguments::Base
+          def validate!
+            error('invalid specification') unless default.present?
+          end
+
+          ##
+          # User-provided value needs to be specified, but it may be an empty string:
+          #
+          # ```yaml
+          # inputs:
+          #   env:
+          #     default: development
+          #
+          # with:
+          #   env: ""
+          # ```
+          #
+          # The configuration above will result in `env` being an empty string.
+          #
+          def to_value
+            value.nil? ? default : value
+          end
+
+          def default
+            spec[:default]
+          end
+
+          def self.matches?(spec)
+            spec.count == 1 && spec.each_key.first == :default
+          end
+        end
+      end
+    end
+  end
+end