fix: resolve transport sort order in browsers (libp2p#333)

* fix: resolve transport sort order in browsers

* fix: update sort logic

Author: jacobheun

src/index.js

@@ -127,9 +127,11 @@ class Switch extends EventEmitter {
 
     // Only listen on transports we actually have addresses for
     return myTransports.filter((ts) => this.transports[ts].filter(myAddrs).length > 0)
-      // push Circuit to be the last proto to be dialed
-      .sort((a) => {
-        return a === Circuit.tag ? 1 : 0
+      // push Circuit to be the last proto to be dialed, and alphabetize the others
+      .sort((a, b) => {
+        if (a === Circuit.tag) return 1
+        if (b === Circuit.tag) return -1
+        return a < b ? -1 : 1
       })
   }
 

test/switch.spec.js

@@ -0,0 +1,37 @@
+/* eslint-env mocha */
+'use strict'
+
+const chai = require('chai')
+const dirtyChai = require('dirty-chai')
+const expect = chai.expect
+chai.use(dirtyChai)
+
+const Switch = require('../src')
+
+describe('Switch', () => {
+  describe('.availableTransports', () => {
+    it('should always sort circuit last', () => {
+      const switchA = new Switch({}, {})
+      const transport = {
+        filter: (addrs) => addrs
+      }
+      const mockPeerInfo = {
+        multiaddrs: {
+          toArray: () => ['a', 'b', 'c']
+        }
+      }
+
+      switchA.transports = {
+        Circuit: transport,
+        TCP: transport,
+        WebSocketStar: transport
+      }
+
+      expect(switchA.availableTransports(mockPeerInfo)).to.eql([
+        'TCP',
+        'WebSocketStar',
+        'Circuit'
+      ])
+    })
+  })
+})