fix: better error message when pubsub is not enabled (#1729)

If pubsub is disabled there's no `pubsub` property on the libp2p node and we get the error "Cannot read property 'subscribe' of undefined". This is really confusing. This PR detects disabled pubsub and throws an error with a better message.

License: MIT
Signed-off-by: Alan Shaw <alan.shaw@protocol.ai>

src/core/components/pubsub.js

@@ -2,6 +2,11 @@
 
 const promisify = require('promisify-es6')
 const setImmediate = require('async/setImmediate')
+const errCode = require('err-code')
+
+const errPubsubDisabled = () => {
+  return errCode(new Error('pubsub experiment is not enabled'), 'ERR_PUBSUB_DISABLED')
+}
 
 module.exports = function pubsub (self) {
   return {
@@ -11,6 +16,12 @@ module.exports = function pubsub (self) {
         options = {}
       }
 
+      if (!self._options.EXPERIMENTAL.pubsub) {
+        return callback
+          ? setImmediate(() => callback(errPubsubDisabled()))
+          : Promise.reject(errPubsubDisabled())
+      }
+
       if (!callback) {
         return new Promise((resolve, reject) => {
           self._libp2pNode.pubsub.subscribe(topic, options, handler, (err) => {
@@ -26,6 +37,12 @@ module.exports = function pubsub (self) {
     },
 
     unsubscribe: (topic, handler, callback) => {
+      if (!self._options.EXPERIMENTAL.pubsub) {
+        return callback
+          ? setImmediate(() => callback(errPubsubDisabled()))
+          : Promise.reject(errPubsubDisabled())
+      }
+
       self._libp2pNode.pubsub.unsubscribe(topic, handler)
 
       if (!callback) {
@@ -36,18 +53,30 @@ module.exports = function pubsub (self) {
     },
 
     publish: promisify((topic, data, callback) => {
+      if (!self._options.EXPERIMENTAL.pubsub) {
+        return setImmediate(() => callback(errPubsubDisabled()))
+      }
       self._libp2pNode.pubsub.publish(topic, data, callback)
     }),
 
     ls: promisify((callback) => {
+      if (!self._options.EXPERIMENTAL.pubsub) {
+        return setImmediate(() => callback(errPubsubDisabled()))
+      }
       self._libp2pNode.pubsub.ls(callback)
     }),
 
     peers: promisify((topic, callback) => {
+      if (!self._options.EXPERIMENTAL.pubsub) {
+        return setImmediate(() => callback(errPubsubDisabled()))
+      }
       self._libp2pNode.pubsub.peers(topic, callback)
     }),
 
     setMaxListeners (n) {
+      if (!self._options.EXPERIMENTAL.pubsub) {
+        throw errPubsubDisabled()
+      }
       self._libp2pNode.pubsub.setMaxListeners(n)
     }
   }

test/core/pubsub.spec.js

@@ -0,0 +1,151 @@
+/* eslint max-nested-callbacks: ["error", 8] */
+/* eslint-env mocha */
+'use strict'
+
+const hat = require('hat')
+const chai = require('chai')
+const dirtyChai = require('dirty-chai')
+const expect = chai.expect
+chai.use(dirtyChai)
+
+const IPFS = require('../../src')
+const createTempRepo = require('../utils/create-repo-nodejs')
+
+describe('pubsub disabled', () => {
+  let ipfs
+  let repo
+
+  before(function (done) {
+    this.timeout(20 * 1000)
+
+    repo = createTempRepo()
+    ipfs = new IPFS({
+      repo,
+      config: {
+        Addresses: {
+          Swarm: []
+        }
+      },
+      preload: {
+        enabled: false
+      },
+      EXPERIMENTAL: {
+        pubsub: false
+      }
+    })
+
+    ipfs.on('ready', done)
+  })
+
+  after((done) => ipfs.stop(done))
+
+  after((done) => repo.teardown(done))
+
+  it('should not allow subscribe if disabled', done => {
+    const topic = hat()
+    const handler = () => done(new Error('unexpected message'))
+    ipfs.pubsub.subscribe(topic, handler, (err) => {
+      expect(err).to.exist()
+      expect(err.code).to.equal('ERR_PUBSUB_DISABLED')
+      done()
+    })
+  })
+
+  it('should not allow subscribe if disabled (promised)', async () => {
+    try {
+      const topic = hat()
+      const handler = () => { throw new Error('unexpected message') }
+      await ipfs.pubsub.subscribe(topic, handler)
+    } catch (err) {
+      return expect(err.code).to.equal('ERR_PUBSUB_DISABLED')
+    }
+    throw new Error('expected error to be thrown')
+  })
+
+  it('should not allow unsubscribe if disabled', done => {
+    const topic = hat()
+    const handler = () => done(new Error('unexpected message'))
+    ipfs.pubsub.unsubscribe(topic, handler, (err) => {
+      expect(err).to.exist()
+      expect(err.code).to.equal('ERR_PUBSUB_DISABLED')
+      done()
+    })
+  })
+
+  it('should not allow unsubscribe if disabled (promised)', async () => {
+    try {
+      const topic = hat()
+      const handler = () => { throw new Error('unexpected message') }
+      await ipfs.pubsub.unsubscribe(topic, handler)
+    } catch (err) {
+      return expect(err.code).to.equal('ERR_PUBSUB_DISABLED')
+    }
+    throw new Error('expected error to be thrown')
+  })
+
+  it('should not allow publish if disabled', done => {
+    const topic = hat()
+    const msg = Buffer.from(hat())
+    ipfs.pubsub.publish(topic, msg, (err) => {
+      expect(err).to.exist()
+      expect(err.code).to.equal('ERR_PUBSUB_DISABLED')
+      done()
+    })
+  })
+
+  it('should not allow publish if disabled (promised)', async () => {
+    try {
+      const topic = hat()
+      const msg = Buffer.from(hat())
+      await ipfs.pubsub.publish(topic, msg)
+    } catch (err) {
+      return expect(err.code).to.equal('ERR_PUBSUB_DISABLED')
+    }
+    throw new Error('expected error to be thrown')
+  })
+
+  it('should not allow ls if disabled', done => {
+    ipfs.pubsub.ls((err) => {
+      expect(err).to.exist()
+      expect(err.code).to.equal('ERR_PUBSUB_DISABLED')
+      done()
+    })
+  })
+
+  it('should not allow ls if disabled (promised)', async () => {
+    try {
+      await ipfs.pubsub.ls()
+    } catch (err) {
+      return expect(err.code).to.equal('ERR_PUBSUB_DISABLED')
+    }
+    throw new Error('expected error to be thrown')
+  })
+
+  it('should not allow peers if disabled', done => {
+    const topic = hat()
+    ipfs.pubsub.peers(topic, (err) => {
+      expect(err).to.exist()
+      expect(err.code).to.equal('ERR_PUBSUB_DISABLED')
+      done()
+    })
+  })
+
+  it('should not allow peers if disabled (promised)', async () => {
+    try {
+      const topic = hat()
+      await ipfs.pubsub.peers(topic)
+    } catch (err) {
+      return expect(err.code).to.equal('ERR_PUBSUB_DISABLED')
+    }
+    throw new Error('expected error to be thrown')
+  })
+
+  it('should not allow setMaxListeners if disabled', async () => {
+    try {
+      await ipfs.pubsub.setMaxListeners(100)
+    } catch (err) {
+      return expect(err.code).to.equal('ERR_PUBSUB_DISABLED')
+    }
+    throw new Error('expected error to be thrown')
+  })
+})