Only test long-running tests if CI env var

Author: kddnewton

test/idempotency_test.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-return if ENV["FAST"]
+return unless ENV["CI"]
 require_relative "test_helper"
 
 module SyntaxTree

test/visitor_test.rb

@@ -3,7 +3,7 @@
 require_relative "test_helper"
 
 class VisitorTest < Minitest::Test
-  unless ENV["FAST"]
+  if ENV["CI"]
     def test_visit_all_nodes
       visitor = SyntaxTree::Visitor.new