[test] fix ipv6 test

[dcharbonnier]

Seams a bit complicated but it's more consistent than simply skipping silently a test.
If the test is skipped it will be mentioned on the result (maybe we should raise an error during ci if a test is skipped) and the test will pass on more machine trying a list of potential alias for the loop-back.

with const hostsCandidates = ['localhost'];

  WebSocket
    options
      - accepts the family option

with const hostsCandidates = ['localhost', 'ip6-loopback'];

  WebSocket
    options
      ✓ accepts the family option

with const hostsCandidates = ['localhost', 'ip6-allnodes'];

  WebSocket
    options
      1) accepts the family option


  0 passing (42ms)
  1 failing

  1) WebSocket
       options
         accepts the family option:
     Error: connect ENETUNREACH ff02::1:39758 - Local (:::0)

[lpinca]

What do you think about this?

diff --git a/test/WebSocket.test.js b/test/WebSocket.test.js
index 178dbfd..6e8318e 100644
--- a/test/WebSocket.test.js
+++ b/test/WebSocket.test.js
@@ -7,7 +7,9 @@ const assert = require('assert');
 const crypto = require('crypto');
 const https = require('https');
 const http = require('http');
+const dns = require('dns');
 const net = require('net');
+const os = require('os');
 const fs = require('fs');
 
 const constants = require('../lib/Constants');
@@ -95,20 +97,35 @@ describe('WebSocket', function () {
     });
 
     it('accepts the family option', function (done) {
-      const wss = new WebSocket.Server({ host: '::1', port: 0 }, () => {
-        const port = wss._server.address().port;
-        const ws = new WebSocket(`ws://localhost:${port}`, { family: 6 });
+      const re = process.platform === 'win32' ? /Loopback Pseudo-Interface/ : /lo/;
+      const ifaces = os.networkInterfaces();
+      const hasIPv6 = Object.keys(ifaces).some((name) => {
+        return re.test(name) && ifaces[name].some((info) => info.family === 'IPv6');
       });
 
-      wss.on('error', (err) => {
-        // Skip this test on machines where IPv6 is not supported.
-        if (err.code === 'EADDRNOTAVAIL') err = undefined;
-        wss.close(() => done(err));
-      });
+      // Skip this test on machines where IPv6 is not supported.
+      if (!hasIPv6) return done();
 
-      wss.on('connection', (ws, req) => {
-        assert.strictEqual(req.connection.remoteAddress, '::1');
-        wss.close(done);
+      dns.lookup('localhost', { family: 6, all: true }, (err, addresses) => {
+        // Skip this test if localhost does not resolve to ::1.
+        if (err) {
+          if (err.code === 'ENOTFOUND' || err.code === 'EAI_AGAIN') {
+            err = undefined;
+          }
+          return done(err);
+        }
+
+        if (!addresses.some((val) => val.address === '::1')) return done();
+
+        const wss = new WebSocket.Server({ host: '::1', port: 0 }, () => {
+          const port = wss._server.address().port;
+          const ws = new WebSocket(`ws://localhost:${port}`, { family: 6 });
+        });
+
+        wss.on('connection', (ws, req) => {
+          assert.strictEqual(req.connection.remoteAddress, '::1');
+          wss.close(done);
+        });
       });
     });
   });

It's a little better as it doesn't run the test multiple times if both localhost and ip6-loopback resolves to ::1.

[lpinca]

We can use skip() as long as we are consistent with other skipped tests, but I'm not very happy with trying multiple aliases. If IPv6 is enabled on a particular machine and localhost does not resolve to ::1, I think that it is something that needs to be fixed on that particular machine.

[dcharbonnier]

I would replace if (!hasIPv6) return done(); with if (!hasIPv6) return this.skip(); because the test don't pass it's just skipped.

And with this change the test will be skipped (or succeed without testing anything). My /etc/hosts is standard, there is nothing strange, just a regular linux machine.
I agree that testing random domain names is not a good idea and passing the test twice is useless, we can add an other variable to skip the second test if the first one was a success, I wanted to keep it has simple as possible but it's not "nice". With await it would be wait more easy to make it "look" good.

Btw the test is probably skipped on the CI and it's invisible ;-)

[dcharbonnier]

For example Red Hat Enterprise Linux 5

127.0.0.1        localhost.localdomain localhost
::1              localhost6.localdomain6 localhost6

[lpinca]

@dcharbonnier yes same is on fedora but if you do

ping6 localhost

or try to resolve with dns.lookup('localhost', { family: 6 }, cb) it works. Same is for plain Ubuntu, macOS, etc.

[dcharbonnier]

➜  ~ salt "*"  cmd.run "ping6 -c 1 localhost"|grep Cannot|wc -l
35
➜  ~ salt "*"  cmd.run "ping6 -c 1 localhost"|grep received|wc -l
65
➜  ~ salt "*"  cmd.run "test -f /proc/net/if_inet6 && echo 'IPv6 supported'"|grep supported|wc -l
100

but ok, let's change it with your proposal will see

[lpinca]

You can update this PR if you want.

[dcharbonnier]

easier to push your branch :-)

[lpinca]

Thank you.

[dcharbonnier]

Thank you, so now we know this test never pass in the CI ;-)

[lpinca]

It passes on AppVeyor and it used to pass on Travis CI when it was possible to bind the server on ::1, see https://travis-ci.org/websockets/ws/jobs/295237782.