Add liquid variable class and specs (#615)

app/liquid_tags/liquid_variable.rb

@@ -0,0 +1,7 @@
+module Liquid
+  class Variable
+    def initialize(_markup, _parse_context)
+      raise StandardError, "Liquid variables are disabled"
+    end
+  end
+end

spec/labor/markdown_parser_spec.rb

@@ -83,4 +83,28 @@ RSpec.describe MarkdownParser do
       expect(generate_and_parse_markdown(inline_code)).to include("<a")
     end
   end
+
+  context "when using Liquid variables" do
+    it "prevents Liquid variables" do
+      expect { generate_and_parse_markdown("{{ 'something' }}") }.to raise_error(StandardError)
+    end
+
+    it "allows Liquid variables in codeblocks" do
+      expect { generate_and_parse_markdown("```\n{{ 'something' }}\n```") }.not_to raise_error
+    end
+
+    it "renders the text in the codeblock properly" do
+      result = generate_and_parse_markdown("```\n{{ 'something' }}\n```")
+      expect(result).to include("{{ 'something' }}")
+    end
+
+    it "allows Liquid variables within inline code" do
+      expect { generate_and_parse_markdown("`{{ 'something' }}`") }.not_to raise_error
+    end
+
+    it "renders the inline code with the text properly" do
+      result = generate_and_parse_markdown("`{{ 'something' }}`")
+      expect(result).to include("{{ 'something' }}")
+    end
+  end
 end