dns: add deprecation code and fix tests

nodejs · Sep 30, 2018 · 197af1c · 197af1c
1 parent 0ae969f
commit 197af1c
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diff --git a/doc/api/deprecations.md b/doc/api/deprecations.md
@@ -2214,6 +2214,22 @@ the `_handle` property of the `Cipher`, `Decipher`, `DiffieHellman`,
 Using the `_handle` property to access the native object is deprecated because
 improper use of the native object can lead to crashing the application.
 
+<a id="DEP0118"></a>
+### DEP0118: dns.lookup supports for falsy hostname
+<!-- YAML
+changes:
+  - version: REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/23173
+    description: Runtime deprecation.
+-->
+
+Type: Runtime
+
+Previous versions of Node.js support `dns.lookup` a falsy hostname like
+`dns.lookup(false)` for the reason of backward compatibility long before.
+This behavior is undocumented and seems useless in real world apps. We
+might make invalid hostname throw in the future.
+
 [`--pending-deprecation`]: cli.html#cli_pending_deprecation
 [`Buffer.allocUnsafeSlow(size)`]: buffer.html#buffer_class_method_buffer_allocunsafeslow_size
 [`Buffer.from(array)`]: buffer.html#buffer_class_method_buffer_from_array

diff --git a/lib/internal/dns/utils.js b/lib/internal/dns/utils.js
@@ -146,6 +146,7 @@ function emitInvalidHostnameWarning(hostname) {
     `The provided hostname "${hostname}" is not a valid ` +
     'hostname, and is supported in the dns module solely for compatibility.',
     'DeprecationWarning',
+    'DEP0118'
   );
 }
 

diff --git a/test/parallel/test-dns-lookup.js b/test/parallel/test-dns-lookup.js
@@ -36,10 +36,12 @@ common.expectWarning({
     [
       'The provided hostname "false" is not a valid ' +
       'hostname, and is supported in the dns module solely for compatibility.',
+      'DEP0118',
     ],
     [
       'The provided hostname "false" is not a valid ' +
       'hostname, and is supported in the dns module solely for compatibility.',
+      'DEP0118',
     ]
   ],
 });

diff --git a/test/parallel/test-dns.js b/test/parallel/test-dns.js
@@ -166,7 +166,7 @@ assert.deepStrictEqual(dns.getServers(), []);
   const errorReg = common.expectsError({
     code: 'ERR_INVALID_ARG_TYPE',
     type: TypeError,
-    message: /^The "hostname" argument must be one of type string or falsy/
+    message: /^The "hostname" argument must be of type string\. Received type .*/
   }, 10);
 
   assert.throws(() => dns.lookup({}, common.mustNotCall()), errorReg);