test(isc): skip the differential gate inside the example when the artifact is absent

Author: ronaldtse

spec/interscript/isc/parg_artifact_spec.rb

@@ -11,9 +11,9 @@
 
   skip "maps checkout not present" if maps.empty?
   skip "parsanol lacks PARG (needs >= 1.3.61)" unless Interscript::Isc::Parser.respond_to?(:artifact)
-      skip "artifact not shipped (parsanol#5 — compiler mistranslates; DSL is the engine)" unless File.exist?(Interscript::Isc::Parser::ARTIFACT_PATH)
 
   it "parses every corpus map identically via artifact and DSL" do
+    skip "artifact not shipped (parsanol#5 — compiler mistranslates; DSL is the engine)" unless File.exist?(Interscript::Isc::Parser::ARTIFACT_PATH)
     failures = []
 
     maps.each do |path|