feat: add check for protector and enforced pnet

fix: update protector config and tests
docs: add private network info to the readme
test: fix an issue with config

test/node.js

@@ -1,5 +1,6 @@
 'use strict'
 
+require('./pnet.node')
 require('./transports.node')
 require('./stream-muxing.node')
 require('./peer-discovery.node')

test/pnet.node.js

@@ -0,0 +1,90 @@
+/* eslint-env mocha */
+'use strict'
+
+const chai = require('chai')
+chai.use(require('dirty-chai'))
+const expect = chai.expect
+const PeerInfo = require('peer-info')
+const PeerId = require('peer-id')
+const waterfall = require('async/waterfall')
+const WS = require('libp2p-websockets')
+const defaultsDeep = require('@nodeutils/defaults-deep')
+
+const Libp2p = require('../src')
+
+describe('private network', () => {
+  let config
+
+  before((done) => {
+    waterfall([
+      (cb) => PeerId.create({ bits: 512 }, cb),
+      (peerId, cb) => PeerInfo.create(peerId, cb),
+      (peerInfo, cb) => {
+        config = {
+          peerInfo,
+          modules: {
+            transport: [ WS ]
+          }
+        }
+        cb()
+      }
+    ], () => done())
+  })
+
+  describe('enforced network protection', () => {
+    before(() => {
+      process.env.LIBP2P_FORCE_PNET = 1
+    })
+
+    after(() => {
+      delete process.env.LIBP2P_FORCE_PNET
+    })
+
+    it('should throw an error without a provided protector', () => {
+      expect(() => {
+        return new Libp2p(config)
+      }).to.throw('Private network is enforced, but no protector was provided')
+    })
+
+    it('should create a libp2p node with a provided protector', () => {
+      let node
+      let protector = {
+        psk: '123',
+        tag: '/psk/1.0.0',
+        protect: () => { }
+      }
+
+      expect(() => {
+        let options = defaultsDeep(config, {
+          modules: {
+            connProtector: protector
+          }
+        })
+
+        node = new Libp2p(options)
+        return node
+      }).to.not.throw()
+      expect(node._switch.protector).to.deep.equal(protector)
+    })
+
+    it('should throw an error if the protector does not have a protect method', () => {
+      expect(() => {
+        let options = defaultsDeep(config, {
+          modules: {
+            connProtector: { }
+          }
+        })
+
+        return new Libp2p(options)
+      }).to.throw()
+    })
+  })
+
+  describe('network protection not enforced', () => {
+    it('should not throw an error with no provided protector', () => {
+      expect(() => {
+        return new Libp2p(config)
+      }).to.not.throw()
+    })
+  })
+})