Add CLI Base class for command line code (#25106)

spec/lib/mastodon/cli/preview_cards_spec.rb

@@ -0,0 +1,12 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+require 'mastodon/cli/preview_cards'
+
+describe Mastodon::CLI::PreviewCards do
+  describe '.exit_on_failure?' do
+    it 'returns true' do
+      expect(described_class.exit_on_failure?).to be true
+    end
+  end
+end