test: fix flaky test-tls-connect-address-family

Skip test if localhost does not resolve to ::1.

Fixes: nodejs#7288

Author: Trott

test/parallel/test-tls-connect-address-family.js

@@ -5,28 +5,41 @@ if (!common.hasCrypto) {
   return;
 }
 
-const assert = require('assert');
-const tls = require('tls');
-
 if (!common.hasIPv6) {
   common.skip('no IPv6 support');
   return;
 }
 
-const ciphers = 'AECDH-NULL-SHA';
-tls.createServer({ ciphers }, function() {
-  this.close();
-}).listen(common.PORT, '::1', function() {
-  const options = {
-    host: 'localhost',
-    port: common.PORT,
-    family: 6,
-    ciphers: ciphers,
-    rejectUnauthorized: false,
-  };
-  // Will fail with ECONNREFUSED if the address family is not honored.
-  tls.connect(options).once('secureConnect', common.mustCall(function() {
-    assert.strictEqual('::1', this.remoteAddress);
-    this.destroy();
+const assert = require('assert');
+const tls = require('tls');
+const dns = require('dns');
+
+function runTest() {
+  const ciphers = 'AECDH-NULL-SHA';
+  tls.createServer({ ciphers }, common.mustCall(function() {
+    this.close();
+  })).listen(common.PORT, '::1', common.mustCall(function() {
+    const options = {
+      host: 'localhost',
+      port: common.PORT,
+      family: 6,
+      ciphers: ciphers,
+      rejectUnauthorized: false,
+    };
+    // Will fail with ECONNREFUSED if the address family is not honored.
+    tls.connect(options).once('secureConnect', common.mustCall(function() {
+      assert.strictEqual('::1', this.remoteAddress);
+      this.destroy();
+    }));
   }));
+}
+
+dns.lookup('localhost', {family: 6, all: true}, (err, addresses) => {
+  if (err)
+    throw err;
+
+  if (addresses.some((val) => { return val.address === '::1'; }))
+    runTest();
+  else
+    common.skip('localhost does not resolve to ::1');
 });