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>

test/topology/multicodec-topology.spec.js

@@ -0,0 +1,40 @@
+/* eslint-env mocha */
+'use strict'
+
+const tests = require('../../src/topology/tests/multicodec-topology')
+const MulticodecTopology = require('../../src/topology/multicodec-topology')
+const MockPeerStore = require('./mock-peer-store')
+
+describe('multicodec topology compliance tests', () => {
+  tests({
+    setup (properties, registrar) {
+      const multicodecs = ['/echo/1.0.0']
+      const handlers = {
+        onConnect: () => { },
+        onDisconnect: () => { }
+      }
+
+      const topology = new MulticodecTopology({
+        multicodecs,
+        handlers,
+        ...properties
+      })
+
+      if (!registrar) {
+        const peerStore = new MockPeerStore([])
+
+        registrar = {
+          peerStore,
+          getConnection: () => { }
+        }
+      }
+
+      topology.registrar = registrar
+
+      return topology
+    },
+    teardown () {
+      // cleanup resources created by setup()
+    }
+  })
+})