1 files changed, 67 insertions, 0 deletions
diff --git a/spec/support/rspec_order.rb b/spec/support/rspec_order.rb
new file mode 100644
index 00000000000..c128e18b38e
--- /dev/null
+++ b/spec/support/rspec_order.rb
@@ -0,0 +1,67 @@
+# frozen_string_literal: true
+
+module Support
+  module RspecOrder
+    TODO_YAML = File.join(__dir__, 'rspec_order_todo.yml')
+
+    module_function
+
+    def order_for(example_group)
+      order_from_env || random_order(example_group)
+    end
+
+    def order_from_env
+      return @order_from_env if defined?(@order_from_env)
+
+      # Passing custom defined order via `--order NAME` is not supported.
+      # For example, `--order reverse` does not work so we are passing it via
+      # environment variable RSPEC_ORDER.
+      @order_from_env = ENV['RSPEC_ORDER']
+    end
+
+    def random_order(example_group)
+      path = example_group.metadata.fetch(:file_path)
+
+      :random unless potential_order_dependent?(path)
+    end
+
+    def potential_order_dependent?(path)
+      @todo ||= YAML.load_file(TODO_YAML).to_set # rubocop:disable Gitlab/PredicateMemoization
+
+      @todo.include?(path)
+    end
+
+    # Adds '# order <ORDER>` below the example group description if the order
+    # has been set to help debugging in case of failure.
+    #
+    # Previously, we've modified metadata[:description] directly but that led
+    # to bugs. See https://gitlab.com/gitlab-org/gitlab/-/merge_requests/96137
+    module DocumentationFormatterPatch
+      # See https://github.com/rspec/rspec-core/blob/v3.11.0/lib/rspec/core/formatters/documentation_formatter.rb#L24-L29
+      def example_group_started(notification)
+        super
+
+        order = notification.group.metadata[:order]
+        return unless order
+
+        output.puts "#{current_indentation}# order #{order}"
+      end
+    end
+  end
+end
+
+RSpec::Core::Formatters::DocumentationFormatter.prepend Support::RspecOrder::DocumentationFormatterPatch
+
+RSpec.configure do |config|
+  # Useful to find order-dependent specs.
+  config.register_ordering(:reverse, &:reverse)
+
+  # Randomization can be reproduced across test runs.
+  Kernel.srand config.seed
+
+  config.on_example_group_definition do |example_group|
+    order = Support::RspecOrder.order_for(example_group)
+
+    example_group.metadata[:order] = order.to_sym if order
+  end
+end