tests(helpers): separate dns_mock module (#13617)

https://konghq.atlassian.net/browse/KAG-5321

spec/details/dns.lua

@@ -0,0 +1,213 @@
+local cjson = require("cjson.safe")
+
+
+----------------
+-- DNS-record mocking.
+-- These function allow to create mock dns records that the test Kong instance
+-- will use to resolve names. The created mocks are injected by the `start_kong`
+-- function.
+-- @usage
+-- -- Create a new DNS mock and add some DNS records
+-- local fixtures = {
+--   dns_mock = helpers.dns_mock.new { mocks_only = true }
+-- }
+--
+-- fixtures.dns_mock:SRV {
+--   name = "my.srv.test.com",
+--   target = "a.my.srv.test.com",
+--   port = 80,
+-- }
+-- fixtures.dns_mock:SRV {
+--   name = "my.srv.test.com",     -- adding same name again: record gets 2 entries!
+--   target = "b.my.srv.test.com", -- a.my.srv.test.com and b.my.srv.test.com
+--   port = 8080,
+-- }
+-- fixtures.dns_mock:A {
+--   name = "a.my.srv.test.com",
+--   address = "127.0.0.1",
+-- }
+-- fixtures.dns_mock:A {
+--   name = "b.my.srv.test.com",
+--   address = "127.0.0.1",
+-- }
+-- @section DNS-mocks
+
+
+local dns_mock = {}
+
+
+dns_mock.__index = dns_mock
+dns_mock.__tostring = function(self)
+  -- fill array to prevent json encoding errors
+  local out = {
+    mocks_only = self.mocks_only,
+    records = {}
+  }
+  for i = 1, 33 do
+    out.records[i] = self[i] or {}
+  end
+  local json = assert(cjson.encode(out))
+  return json
+end
+
+
+local TYPE_A, TYPE_AAAA, TYPE_CNAME, TYPE_SRV = 1, 28, 5, 33
+
+
+--- Creates a new DNS mock.
+-- The options table supports the following fields:
+--
+-- - `mocks_only`: boolean, if set to `true` then only mock records will be
+--   returned. If `falsy` it will fall through to an actual DNS lookup.
+-- @function dns_mock.new
+-- @param options table with mock options
+-- @return dns_mock object
+-- @usage
+-- local mock = helpers.dns_mock.new { mocks_only = true }
+function dns_mock.new(options)
+  return setmetatable(options or {}, dns_mock)
+end
+
+
+--- Adds an SRV record to the DNS mock.
+-- Fields `name`, `target`, and `port` are required. Other fields get defaults:
+--
+-- * `weight`; 20
+-- * `ttl`; 600
+-- * `priority`; 20
+-- @param rec the mock DNS record to insert
+-- @return true
+function dns_mock:SRV(rec)
+  if self == dns_mock then
+    error("can't operate on the class, you must create an instance", 2)
+  end
+  if getmetatable(self or {}) ~= dns_mock then
+    error("SRV method must be called using the colon notation", 2)
+  end
+  assert(rec, "Missing record parameter")
+  local name = assert(rec.name, "No name field in SRV record")
+
+  self[TYPE_SRV] = self[TYPE_SRV] or {}
+  local query_answer = self[TYPE_SRV][name]
+  if not query_answer then
+    query_answer = {}
+    self[TYPE_SRV][name] = query_answer
+  end
+
+  table.insert(query_answer, {
+    type = TYPE_SRV,
+    name = name,
+    target = assert(rec.target, "No target field in SRV record"),
+    port = assert(rec.port, "No port field in SRV record"),
+    weight = rec.weight or 10,
+    ttl = rec.ttl or 600,
+    priority = rec.priority or 20,
+    class = rec.class or 1
+  })
+  return true
+end
+
+
+--- Adds an A record to the DNS mock.
+-- Fields `name` and `address` are required. Other fields get defaults:
+--
+-- * `ttl`; 600
+-- @param rec the mock DNS record to insert
+-- @return true
+function dns_mock:A(rec)
+  if self == dns_mock then
+    error("can't operate on the class, you must create an instance", 2)
+  end
+  if getmetatable(self or {}) ~= dns_mock then
+    error("A method must be called using the colon notation", 2)
+  end
+  assert(rec, "Missing record parameter")
+  local name = assert(rec.name, "No name field in A record")
+
+  self[TYPE_A] = self[TYPE_A] or {}
+  local query_answer = self[TYPE_A][name]
+  if not query_answer then
+    query_answer = {}
+    self[TYPE_A][name] = query_answer
+  end
+
+  table.insert(query_answer, {
+    type = TYPE_A,
+    name = name,
+    address = assert(rec.address, "No address field in A record"),
+    ttl = rec.ttl or 600,
+    class = rec.class or 1
+  })
+  return true
+end
+
+
+--- Adds an AAAA record to the DNS mock.
+-- Fields `name` and `address` are required. Other fields get defaults:
+--
+-- * `ttl`; 600
+-- @param rec the mock DNS record to insert
+-- @return true
+function dns_mock:AAAA(rec)
+  if self == dns_mock then
+    error("can't operate on the class, you must create an instance", 2)
+  end
+  if getmetatable(self or {}) ~= dns_mock then
+    error("AAAA method must be called using the colon notation", 2)
+  end
+  assert(rec, "Missing record parameter")
+  local name = assert(rec.name, "No name field in AAAA record")
+
+  self[TYPE_AAAA] = self[TYPE_AAAA] or {}
+  local query_answer = self[TYPE_AAAA][name]
+  if not query_answer then
+    query_answer = {}
+    self[TYPE_AAAA][name] = query_answer
+  end
+
+  table.insert(query_answer, {
+    type = TYPE_AAAA,
+    name = name,
+    address = assert(rec.address, "No address field in AAAA record"),
+    ttl = rec.ttl or 600,
+    class = rec.class or 1
+  })
+  return true
+end
+
+
+--- Adds a CNAME record to the DNS mock.
+-- Fields `name` and `cname` are required. Other fields get defaults:
+--
+-- * `ttl`; 600
+-- @param rec the mock DNS record to insert
+-- @return true
+function dns_mock:CNAME(rec)
+  if self == dns_mock then
+    error("can't operate on the class, you must create an instance", 2)
+  end
+  if getmetatable(self or {}) ~= dns_mock then
+    error("CNAME method must be called using the colon notation", 2)
+  end
+  assert(rec, "Missing record parameter")
+  local name = assert(rec.name, "No name field in CNAME record")
+
+  self[TYPE_CNAME] = self[TYPE_CNAME] or {}
+  local query_answer = self[TYPE_CNAME][name]
+  if not query_answer then
+    query_answer = {}
+    self[TYPE_CNAME][name] = query_answer
+  end
+
+  table.insert(query_answer, {
+    type = TYPE_CNAME,
+    name = name,
+    cname = assert(rec.cname, "No cname field in CNAME record"),
+    ttl = rec.ttl or 600,
+    class = rec.class or 1
+  })
+  return true
+end
+
+
+return dns_mock