From b108fa6722c5e0f57961a3c13009dd2a81bf38c3 Mon Sep 17 00:00:00 2001
From: David Ortiz <z.david.ortiz@gmail.com>
Date: Tue, 14 Nov 2017 11:23:24 +0100
Subject: [PATCH] linked_list: raise error when trying to modify read-only list

---
 apicast/src/linked_list.lua | 5 ++++-
 spec/linked_list_spec.lua   | 2 +-
 spec/policy_chain_spec.lua  | 6 +++---
 3 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/apicast/src/linked_list.lua b/apicast/src/linked_list.lua
index 607523356..cbc90bace 100644
--- a/apicast/src/linked_list.lua
+++ b/apicast/src/linked_list.lua
@@ -1,4 +1,5 @@
 local setmetatable = setmetatable
+local error = error
 
 local _M = {
 
@@ -14,7 +15,9 @@ end
 
 local ro_mt = {
     __index = __index,
-    __newindex = noop,
+    __newindex = function()
+        error("readonly list")
+    end,
 }
 
 local rw_mt = {
diff --git a/spec/linked_list_spec.lua b/spec/linked_list_spec.lua
index 3278cd434..e6fa7d62e 100644
--- a/spec/linked_list_spec.lua
+++ b/spec/linked_list_spec.lua
@@ -14,7 +14,7 @@ describe('linked_list', function()
     it('returns a list that cannot be modified', function()
       local list = linked_list.readonly({ a = 1 })
 
-      list.abc = 123
+      assert.has_error(function() list.abc = 123 end, 'readonly list')
       assert.is_nil(list.abc)
     end)
 
diff --git a/spec/policy_chain_spec.lua b/spec/policy_chain_spec.lua
index da02747c0..84547156a 100644
--- a/spec/policy_chain_spec.lua
+++ b/spec/policy_chain_spec.lua
@@ -125,9 +125,9 @@ describe('policy_chain', function()
 
       local shared_data = chain:export()
 
-      -- This does not raise, but it does not do anything.
-      shared_data.new_shared_data = 'some_data'
-
+      assert.has_error(function()
+        shared_data.new_shared_data = 'some_data'
+      end, 'readonly list')
       assert.is_nil(shared_data.new_shared_data)
     end)