From d658007d5c7d16a0a1b9d35adaf2e94541988b4e Mon Sep 17 00:00:00 2001
From: Spencer T Brody <spencer+github@3box.io>
Date: Fri, 7 Jan 2022 15:23:53 -0500
Subject: [PATCH] use error codes

---
 src/errors.js            |  3 ++-
 src/fetch/index.js       |  8 +++++---
 test/fetch/fetch.spec.js | 18 +++++++++---------
 3 files changed, 16 insertions(+), 13 deletions(-)

diff --git a/src/errors.js b/src/errors.js
index 61f308667e..cedb0cfcd0 100644
--- a/src/errors.js
+++ b/src/errors.js
@@ -60,5 +60,6 @@ exports.codes = {
   ERR_INVALID_NEW_PASS_TYPE: 'ERR_INVALID_NEW_PASS_TYPE',
   ERR_INVALID_PASS_LENGTH: 'ERR_INVALID_PASS_LENGTH',
   ERR_NOT_IMPLEMENTED: 'ERR_NOT_IMPLEMENTED',
-  ERR_WRONG_PING_ACK: 'ERR_WRONG_PING_ACK'
+  ERR_WRONG_PING_ACK: 'ERR_WRONG_PING_ACK',
+  ERR_UNHANDLED_CASE: 'ERR_UNHANDLED_CASE'
 }
diff --git a/src/fetch/index.js b/src/fetch/index.js
index 86e1e7d429..5829afda6c 100644
--- a/src/fetch/index.js
+++ b/src/fetch/index.js
@@ -4,6 +4,8 @@ const debug = require('debug')
 const log = Object.assign(debug('libp2p:fetch'), {
   error: debug('libp2p:fetch:err')
 })
+const errCode = require('err-code')
+const { codes } = require('../errors')
 const lp = require('it-length-prefixed')
 const { FetchRequest, FetchResponse } = require('./proto')
 // @ts-ignore it-handshake does not export types
@@ -62,10 +64,10 @@ class FetchProtocol {
       }
       case (FetchResponse.StatusCode.ERROR): {
         const errmsg = (new TextDecoder()).decode(response.data)
-        throw new Error('Error in fetch protocol response: ' + errmsg)
+        throw errCode(new Error('Error in fetch protocol response: ' + errmsg), codes.ERR_INVALID_PARAMETERS)
       }
       default: {
-        throw new Error('Unreachable case')
+        throw errCode(new Error('Unreachable case'), codes.ERR_UNHANDLED_CASE)
       }
     }
   }
@@ -122,7 +124,7 @@ class FetchProtocol {
    */
   registerLookupFunction (prefix, lookup) {
     if (this._lookupFunctions.has(prefix)) {
-      throw new Error("Fetch protocol handler for key prefix '" + prefix + "' already registered")
+      throw errCode(new Error("Fetch protocol handler for key prefix '" + prefix + "' already registered"), codes.ERR_KEY_ALREADY_EXISTS)
     }
     this._lookupFunctions.set(prefix, lookup)
   }
diff --git a/test/fetch/fetch.spec.js b/test/fetch/fetch.spec.js
index 4a37c091fa..aa7cb00d41 100644
--- a/test/fetch/fetch.spec.js
+++ b/test/fetch/fetch.spec.js
@@ -9,6 +9,7 @@ const { NOISE } = require('@chainsafe/libp2p-noise')
 const MDNS = require('libp2p-mdns')
 const { createPeerId } = require('../utils/creators/peer')
 const Fetch = require('../../src/fetch')
+const { codes } = require('../../src/errors')
 
 async function createLibp2pNode (peerId) {
   return await Libp2p.create({
@@ -99,20 +100,19 @@ describe('Fetch Protocol', () => {
     fetch.registerLookupFunction(PREFIX_A, generateLookupFunction(PREFIX_A, DATA_A))
     fetch.mount(receiver)
 
-    try {
-      await Fetch.fetch(sender, receiver.peerId, '/moduleUNKNOWN/foobar')
-      expect.fail("didn't throw")
-    } catch (err) {
-      expect(err).to.be.an('Error')
-      expect(err.message).to.equal('Error in fetch protocol response: No lookup function registered for key: /moduleUNKNOWN/foobar')
-    }
+    await expect(Fetch.fetch(sender, receiver.peerId, '/moduleUNKNOWN/foobar')).to.eventually.be.rejected.with.property('code', codes.ERR_INVALID_PARAMETERS)
   })
 
   it('Registering multiple handlers for same prefix errors', async () => {
     const fetch = new Fetch()
     fetch.registerLookupFunction(PREFIX_A, generateLookupFunction(PREFIX_A, DATA_A))
-    expect(function () {
+
+    try {
       fetch.registerLookupFunction(PREFIX_A, generateLookupFunction(PREFIX_A, DATA_B))
-    }).to.throw('already registered')
+      expect.fail("didn't throw")
+    } catch (err) {
+      expect(err).to.be.an('Error')
+      expect(err.code).to.equal(codes.ERR_KEY_ALREADY_EXISTS)
+    }
   })
 })