feat: add topology interfaces (#7)

* feat: topology

* feat: multicodec-topology

* chore: address review

Co-Authored-By: Jacob Heun <jacobheun@gmail.com>

* chore: remove error from disconnect

* docs: topology

* chore: apply suggestions from code review

Co-Authored-By: Jacob Heun <jacobheun@gmail.com>

src/topology/tests/multicodec-topology.js

@@ -0,0 +1,89 @@
+/* eslint-env mocha */
+
+'use strict'
+
+const chai = require('chai')
+const expect = chai.expect
+chai.use(require('dirty-chai'))
+const sinon = require('sinon')
+
+const PeerId = require('peer-id')
+const PeerInfo = require('peer-info')
+const peers = require('../../utils/peers')
+
+module.exports = (test) => {
+  describe('multicodec topology', () => {
+    let topology, peer
+
+    beforeEach(async () => {
+      topology = await test.setup()
+      if (!topology) throw new Error('missing multicodec topology')
+
+      const id = await PeerId.createFromJSON(peers[0])
+      peer = await PeerInfo.create(id)
+    })
+
+    afterEach(async () => {
+      sinon.restore()
+      await test.teardown()
+    })
+
+    it('should have properties set', () => {
+      expect(topology.multicodecs).to.exist()
+      expect(topology._onConnect).to.exist()
+      expect(topology._onDisconnect).to.exist()
+      expect(topology.peers).to.exist()
+      expect(topology._registrar).to.exist()
+    })
+
+    it('should trigger "onDisconnect" on peer disconnected', () => {
+      sinon.spy(topology, '_onDisconnect')
+      topology.disconnect(peer)
+
+      expect(topology._onDisconnect.callCount).to.equal(1)
+    })
+
+    it('should update peers on protocol change', async () => {
+      sinon.spy(topology, '_updatePeers')
+      expect(topology.peers.size).to.eql(0)
+
+      const id2 = await PeerId.createFromJSON(peers[1])
+      const peer2 = await PeerInfo.create(id2)
+
+      const peerStore = topology._registrar.peerStore
+      peerStore.emit('change:protocols', {
+        peerInfo: peer2,
+        protocols: Array.from(topology.multicodecs)
+      })
+
+      expect(topology._updatePeers.callCount).to.equal(1)
+      expect(topology.peers.size).to.eql(1)
+    })
+
+    it('should disconnect if peer no longer supports a protocol', async () => {
+      sinon.spy(topology, '_onDisconnect')
+      expect(topology.peers.size).to.eql(0)
+
+      const id2 = await PeerId.createFromJSON(peers[1])
+      const peer2 = await PeerInfo.create(id2)
+      const peerStore = topology._registrar.peerStore
+
+      // Peer with the protocol
+      peerStore.emit('change:protocols', {
+        peerInfo: peer2,
+        protocols: Array.from(topology.multicodecs)
+      })
+
+      expect(topology.peers.size).to.eql(1)
+
+      // Peer does not support the protocol anymore
+      peerStore.emit('change:protocols', {
+        peerInfo: peer2,
+        protocols: []
+      })
+
+      expect(topology.peers.size).to.eql(1)
+      expect(topology._onDisconnect.callCount).to.equal(1)
+    })
+  })
+}

src/topology/tests/topology.js

@@ -0,0 +1,46 @@
+/* eslint-env mocha */
+
+'use strict'
+
+const chai = require('chai')
+const expect = chai.expect
+chai.use(require('dirty-chai'))
+const sinon = require('sinon')
+
+const PeerId = require('peer-id')
+const PeerInfo = require('peer-info')
+const peers = require('../../utils/peers')
+
+module.exports = (test) => {
+  describe('topology', () => {
+    let topology, peer
+
+    beforeEach(async () => {
+      topology = await test.setup()
+      if (!topology) throw new Error('missing multicodec topology')
+
+      const id = await PeerId.createFromJSON(peers[0])
+      peer = await PeerInfo.create(id)
+    })
+
+    afterEach(async () => {
+      sinon.restore()
+      await test.teardown()
+    })
+
+    it('should have properties set', () => {
+      expect(topology.min).to.exist()
+      expect(topology.max).to.exist()
+      expect(topology._onConnect).to.exist()
+      expect(topology._onDisconnect).to.exist()
+      expect(topology.peers).to.exist()
+    })
+
+    it('should trigger "onDisconnect" on peer disconnected', () => {
+      sinon.spy(topology, '_onDisconnect')
+      topology.disconnect(peer)
+
+      expect(topology._onDisconnect.callCount).to.equal(1)
+    })
+  })
+}