Fix debugging of tests in Studio (#145)

* Fix debugging of tests in Studio

Copy 'script' directly to new env to make Studio debugger happy, as it does not look into __index, because of security reasons

* Make comment line shorter

Author: amatosov-rbx

src/TestPlan.lua

@@ -194,6 +194,9 @@ function TestNode:expand()
 	for key, value in pairs(self.environment) do
 		callbackEnv[key] = value
 	end
+	-- Copy 'script' directly to new env to make Studio debugger happy.
+	-- Studio debugger does not look into __index, because of security reasons
+	callbackEnv.script = originalEnv.script
 	setfenv(self.callback, callbackEnv)
 
 	local success, result = xpcall(self.callback, function(message)