fix error serialization in parallel mode (#1053)

Author: charlierudolph

package.json

@@ -155,6 +155,7 @@
     "mz": "^2.4.0",
     "progress": "^2.0.0",
     "resolve": "^1.3.3",
+    "serialize-error": "^2.1.0",
     "stack-chain": "^2.0.0",
     "stacktrace-js": "^2.0.0",
     "string-argv": "0.0.2",

src/runtime/parallel/slave.js

@@ -1,8 +1,10 @@
+import _ from 'lodash'
 import { formatLocation } from '../../formatter/helpers'
 import commandTypes from './command_types'
 import EventEmitter from 'events'
 import Promise from 'bluebird'
 import readline from 'readline'
+import serializeError from 'serialize-error'
 import StackTraceFilter from '../stack_trace_filter'
 import supportCodeLibraryBuilder from '../../support_code_library_builder'
 import TestCaseRunner from '../test_case_runner'
@@ -18,6 +20,13 @@ const EVENTS = [
   'test-case-finished',
 ]
 
+function replacerSerializeErrors(key, value) {
+  if (_.isError(value)) {
+    return serializeError(value)
+  }
+  return value
+}
+
 export default class Slave {
   constructor({ cwd, stdin, stdout }) {
     this.initialized = false
@@ -29,7 +38,10 @@ export default class Slave {
     EVENTS.forEach(name => {
       this.eventBroadcaster.on(name, data =>
         this.stdout.write(
-          JSON.stringify({ command: commandTypes.EVENT, name, data }) + '\n'
+          JSON.stringify(
+            { command: commandTypes.EVENT, name, data },
+            replacerSerializeErrors
+          ) + '\n'
         )
       )
     })

yarn.lock

@@ -3695,6 +3695,10 @@ [email protected]:
     range-parser "~1.2.0"
     statuses "~1.3.1"
 
+serialize-error@^2.1.0:
+  version "2.1.0"
+  resolved "https://registry.yarnpkg.com/serialize-error/-/serialize-error-2.1.0.tgz#50b679d5635cdf84667bdc8e59af4e5b81d5f60a"
+
 serve-static@^1.10.0:
   version "1.13.1"
   resolved "https://registry.yarnpkg.com/serve-static/-/serve-static-1.13.1.tgz#4c57d53404a761d8f2e7c1e8a18a47dbf278a719"