generalize cidr parsing and improve lua tests

rootfs/etc/nginx/lua/test/balancer/chash_test.lua

@@ -1,15 +1,12 @@
-function mock_ngx(mock)
-  local _ngx = mock
-  setmetatable(_ngx, {__index = _G.ngx})
-  _G.ngx = _ngx
-end
-
 describe("Balancer chash", function()
+  after_each(function()
+    reset_ngx()
+  end)
 
   describe("balance()", function()
     it("uses correct key for given backend", function()
-      mock_ngx({var = { request_uri = "/alma/armud"}})
-      local balancer_chash = require("balancer.chash")
+      ngx.var = { request_uri = "/alma/armud"}
+      local balancer_chash = require_without_cache("balancer.chash")
 
       local resty_chash = package.loaded["resty.chash"]
       resty_chash.new = function(self, nodes)

rootfs/etc/nginx/lua/test/run.lua

@@ -11,6 +11,8 @@ do
   -- if there's more constants need to be whitelisted for test runs, add here.
   local GLOBALS_ALLOWED_IN_TEST = {
     helpers = true,
+    require_without_cache = true,
+    reset_ngx = true,
   }
   local newindex = function(table, key, value)
     rawset(table, key, value)
@@ -69,6 +71,15 @@ end
 
 ngx.log = function(...) end
 ngx.print = function(...) end
+local original_ngx = ngx
+_G.reset_ngx = function()
+  ngx = original_ngx
+end
+
+_G.require_without_cache = function(module)
+  package.loaded[module] = nil
+  return require(module)
+end
 
 lua_ingress.init_worker()
 

rootfs/etc/nginx/lua/test/util_test.lua

@@ -1,27 +1,16 @@
-local original_ngx = ngx
 local util
 
-local function reset_ngx()
-  _G.ngx = original_ngx
-end
-
-local function mock_ngx(mock)
-  local _ngx = mock
-  setmetatable(_ngx, { __index = ngx })
-  _G.ngx = _ngx
-end
-
 describe("utility", function()
+  before_each(function()
+    ngx.var = { remote_addr = "192.168.1.1", [1] = "nginx/regexp/1/group/capturing" }
+    util = require_without_cache("util")
+  end)
 
   after_each(function()
     reset_ngx()
   end)
 
   describe("ngx_complex_value", function()
-    before_each(function()
-      mock_ngx({ var = { remote_addr = "192.168.1.1", [1] = "nginx/regexp/1/group/capturing" } })
-      util = require("util")
-    end)
 
     local ngx_complex_value = function(data)
       local ret, err = util.parse_complex_value(data)