Add ngx.req function mocks to all test classes

Fixed missing ngx.req.read_body, ngx.req.get_post_args, and
ngx.req.get_headers function mocks that were causing test errors.
These functions are required by the DDoS protection module to
handle POST requests and cookie validation.

All four test classes now properly initialize these mocks:
- TestDDoSProtectionChallenge
- TestDDoSProtectionChallengePaths
- TestDDoSProtectionChallengeQuestion
- TestDDoSProtectionChallengePow

tests/ddos_protection_challenge.lua

@@ -39,6 +39,17 @@ function TestDDoSProtectionChallenge:setup()
     -- Mock ngx.time for consistent testing
     ngx.time = function() return 1000000 end
 
+    -- Add missing ngx.req functions
+    ngx.req.read_body = function() end
+    ngx.req.get_post_args = function()
+        return ngx._post_args or {}
+    end
+    ngx.req.get_headers = function()
+        return ngx._headers or {}
+    end
+    ngx.header = {}
+    ngx.var.request_method = 'GET'
+
     -- Setup module manually (can't use setupTest because it calls resetNgx)
     local ctx = require('ctx')
     local config = require('config')
@@ -224,6 +235,17 @@ function TestDDoSProtectionChallengePaths:setup()
 
     ngx.time = function() return 1000000 end
 
+    -- Add missing ngx.req functions
+    ngx.req.read_body = function() end
+    ngx.req.get_post_args = function()
+        return ngx._post_args or {}
+    end
+    ngx.req.get_headers = function()
+        return ngx._headers or {}
+    end
+    ngx.header = {}
+    ngx.var.request_method = 'GET'
+
     -- Setup module manually
     local ctx = require('ctx')
     local config = require('config')
@@ -381,6 +403,17 @@ function TestDDoSProtectionChallengeQuestion:setup()
 
     ngx.time = function() return 1000000 end
 
+    -- Add missing ngx.req functions
+    ngx.req.read_body = function() end
+    ngx.req.get_post_args = function()
+        return ngx._post_args or {}
+    end
+    ngx.req.get_headers = function()
+        return ngx._headers or {}
+    end
+    ngx.header = {}
+    ngx.var.request_method = 'GET'
+
     -- Setup module manually
     local ctx = require('ctx')
     local config = require('config')
@@ -506,6 +539,17 @@ function TestDDoSProtectionChallengePow:setup()
 
     ngx.time = function() return 1000000 end
 
+    -- Add missing ngx.req functions
+    ngx.req.read_body = function() end
+    ngx.req.get_post_args = function()
+        return ngx._post_args or {}
+    end
+    ngx.req.get_headers = function()
+        return ngx._headers or {}
+    end
+    ngx.header = {}
+    ngx.var.request_method = 'GET'
+
     -- Setup module manually
     local ctx = require('ctx')
     local config = require('config')