feat: interface pubsub (#60)

* feat: interface pubsub

* chore: pubsub router tests

* chore: move pubsub abstractions from gossipsub

* chore: address review

* chore: revamp docs

* chore: add emit self tests to interface

* chore: refactor base tests

* chore: publish should only accept one topic per api call

* chore: normalize msg before emit

* chore: do not reset inbound stream

* chore: apply suggestions from code review

Co-authored-by: Jacob Heun <jacobheun@gmail.com>

* chore: address review

* fix: remove subscribe handler

* chore: remove bits from create peerId

Co-authored-by: Jacob Heun <jacobheun@gmail.com>

* chore: remove delay from topic validators tests

* chore: add event emitter information

* fix: topic validator docs

Co-authored-by: Jacob Heun <jacobheun@gmail.com>

test/pubsub/message.spec.js

@@ -0,0 +1,73 @@
+/* eslint-env mocha */
+'use strict'
+
+const { expect } = require('aegir/utils/chai')
+const sinon = require('sinon')
+
+const PubsubBaseImpl = require('../../src/pubsub')
+const { randomSeqno } = require('../../src/pubsub/utils')
+const {
+  createPeerId,
+  mockRegistrar
+} = require('./utils')
+
+describe('pubsub base messages', () => {
+  let peerId
+  let pubsub
+
+  before(async () => {
+    peerId = await createPeerId()
+    pubsub = new PubsubBaseImpl({
+      debugName: 'pubsub',
+      multicodecs: '/pubsub/1.0.0',
+      libp2p: {
+        peerId: peerId,
+        registrar: mockRegistrar
+      }
+    })
+  })
+
+  afterEach(() => {
+    sinon.restore()
+  })
+
+  it('_buildMessage normalizes and signs messages', async () => {
+    const message = {
+      receivedFrom: peerId.id,
+      from: peerId.id,
+      data: 'hello',
+      seqno: randomSeqno(),
+      topicIDs: ['test-topic']
+    }
+
+    const signedMessage = await pubsub._buildMessage(message)
+    expect(pubsub.validate(signedMessage)).to.not.be.rejected()
+  })
+
+  it('validate with strict signing off will validate a present signature', async () => {
+    const message = {
+      receivedFrom: peerId.id,
+      from: peerId.id,
+      data: 'hello',
+      seqno: randomSeqno(),
+      topicIDs: ['test-topic']
+    }
+
+    sinon.stub(pubsub, 'strictSigning').value(false)
+
+    const signedMessage = await pubsub._buildMessage(message)
+    expect(pubsub.validate(signedMessage)).to.not.be.rejected()
+  })
+
+  it('validate with strict signing requires a signature', async () => {
+    const message = {
+      receivedFrom: peerId.id,
+      from: peerId.id,
+      data: 'hello',
+      seqno: randomSeqno(),
+      topicIDs: ['test-topic']
+    }
+
+    await expect(pubsub.validate(message)).to.be.rejectedWith(Error, 'Signing required and no signature was present')
+  })
+})