Pre-empt EADDRINUSE and show useful error.

lib/api.js

@@ -5,6 +5,7 @@ const path = require('path');
 const istanbul = require('istanbul');
 const util = require('util');
 const assert = require('assert');
+const detect = require('detect-port');
 
 const ConfigValidator = require('./validator');
 const Instrumenter = require('./instrumenter');
@@ -121,6 +122,11 @@ class API {
     let retry = false;
     let address = `http://${this.host}:${this.port}`;
 
+    // Check for port-in-use
+    if (await detect(this.port) !== this.port){
+      throw new Error(this.ui.generate('server-fail', [this.port]))
+    }
+
     if(!this.client) this.client = client; // Prefer client from options
 
     this.collector = new DataCollector(this.instrumenter.instrumentationData);

lib/ui.js

@@ -103,6 +103,10 @@ class AppUI extends UI {
       'istanbul-fail': `${c.red('Istanbul coverage reports could not be generated. ')}`,
 
       'sources-fail': `${c.red('Cannot locate expected contract sources folder: ')} ${args[0]}`,
+
+      'server-fail': `${c.red('Port')} ${args[0]} ${c.red('is already in use.\n')}` +
+                     `${c.red('\tRun: "lsof -i" to find the pid of the process using it.\n')}` +
+                     `${c.red('\tRun: "kill -9 <pid>" to kill it.\n')}`
     }
 
     return this._format(kinds[kind])

package.json

@@ -28,6 +28,7 @@
     "chalk": "^2.4.2",
     "death": "^1.1.0",
     "fs-extra": "^8.1.0",
+    "detect-port": "^1.3.0",
     "ganache-core-sc": "2.7.0-sc.0",
     "ghost-testrpc": "^0.0.2",
     "global-modules": "^2.0.0",

test/units/truffle/errors.js

@@ -126,7 +126,7 @@ describe('Truffle Plugin: error cases', function() {
   });
 
   // This case *does* throw an error, but it's uncatch-able;
-  it.skip('tries to launch with a port already in use', async function(){
+  it('tries to launch with a port already in use', async function(){
     verify.cleanInitialState();
     const server = ganache.server();
 
@@ -139,7 +139,11 @@ describe('Truffle Plugin: error cases', function() {
       await plugin(truffleConfig);
       assert.fail();
     } catch(err){
-      assert(err.message.includes('EADDRINUSE: address already in use :::8545'))
+      assert(
+        err.message.includes('is already in use') &&
+        err.message.includes('lsof'),
+        `Should error on port-in-use with advice: ${err.message}`
+      )
     }
 
     await pify(server.close)();

yarn.lock

@@ -288,6 +288,11 @@ accepts@~1.3.7:
     mime-types "~2.1.24"
     negotiator "0.6.2"
 
+address@^1.0.1:
+  version "1.1.2"
+  resolved "https://registry.yarnpkg.com/address/-/address-1.1.2.tgz#bf1116c9c758c51b7a933d296b72c221ed9428b6"
+  integrity sha512-aT6camzM4xEA54YVJYSqxz1kv4IHnQZRtThJJHhUMRExaU5spC7jX5ugSwTaTgJliIgs4VhZOk7htClvQ/LmRA==
+
 [email protected]:
   version "3.0.0"
   resolved "https://registry.yarnpkg.com/aes-js/-/aes-js-3.0.0.tgz#e21df10ad6c2053295bcbb8dab40b09dbea87e4d"
@@ -1828,7 +1833,7 @@ death@^1.1.0:
   resolved "https://registry.yarnpkg.com/death/-/death-1.1.0.tgz#01aa9c401edd92750514470b8266390c66c67318"
   integrity sha1-AaqcQB7dknUFFEcLgmY5DGbGcxg=
 
-[email protected], debug@^2.2.0, debug@^2.6.8, debug@^2.6.9:
+[email protected], debug@^2.2.0, debug@^2.6.0, debug@^2.6.8, debug@^2.6.9:
   version "2.6.9"
   resolved "https://registry.yarnpkg.com/debug/-/debug-2.6.9.tgz#5d128515df134ff327e90a4c93f4e077a536341f"
   integrity sha512-bC7ElrdJaJnPbAP+1EotYvqZsb3ecl5wi6Bfi6BJTUcNowp6cvspg0jXznRTKDjm/E7AdgFBVeAPVMNcKGsHMA==
@@ -2029,6 +2034,14 @@ detect-indent@^4.0.0:
   dependencies:
     repeating "^2.0.0"
 
+detect-port@^1.3.0:
+  version "1.3.0"
+  resolved "https://registry.yarnpkg.com/detect-port/-/detect-port-1.3.0.tgz#d9c40e9accadd4df5cac6a782aefd014d573d1f1"
+  integrity sha512-E+B1gzkl2gqxt1IhUzwjrxBKRqx1UzC3WLONHinn8S3T6lwV/agVCyitiFOsGJ/eYuEUBvD71MZHy3Pv1G9doQ==
+  dependencies:
+    address "^1.0.1"
+    debug "^2.6.0"
+
 [email protected]:
   version "3.5.0"
   resolved "https://registry.yarnpkg.com/diff/-/diff-3.5.0.tgz#800c0dd1e0a8bfbc95835c202ad220fe317e5a12"