dns: return TypeError on invalid resolve() input

Synchronize the argument list for `dns.resolve()` with what's in the
documentation.

Improve the error for a bad `rrtype` to be a `TypeError` rather than an
`Error`.

Author: Trott

lib/dns.js

@@ -291,22 +291,21 @@ resolveMap.NAPTR = resolver('queryNaptr');
 resolveMap.SOA = resolver('querySoa');
 
 
-function resolve(hostname, type_, callback_) {
-  var resolver, callback;
-  if (typeof type_ === 'string') {
-    resolver = resolveMap[type_];
-    callback = callback_;
-  } else if (typeof type_ === 'function') {
+function resolve(hostname, rrtype, callback) {
+  var resolver;
+  if (typeof rrtype === 'string') {
+    resolver = resolveMap[rrtype];
+  } else if (typeof rrtype === 'function') {
     resolver = resolveMap.A;
-    callback = type_;
+    callback = rrtype;
   } else {
-    throw new Error('"type" argument must be a string');
+    throw new TypeError('"rrtype" argument must be a string');
   }
 
   if (typeof resolver === 'function') {
     return resolver(hostname, callback);
   } else {
-    throw new Error(`Unknown type "${type_}"`);
+    throw new Error(`Unknown type "${rrtype}"`);
   }
 }
 

test/parallel/test-dns.js

@@ -91,10 +91,8 @@ assert.doesNotThrow(() => dns.setServers([]));
 assert.deepStrictEqual(dns.getServers(), []);
 
 assert.throws(() => {
-  dns.resolve('test.com', [], common.mustNotCall());
-}, function(err) {
-  return !(err instanceof TypeError);
-}, 'Unexpected error');
+  dns.resolve('example.com', [], common.mustNotCall());
+}, /^TypeError: "rrtype" argument must be a string$/);
 
 // dns.lookup should accept only falsey and string values
 {