fix(reporter): Better handling of non string error

Ref #1969, #1988

lib/reporter.js

@@ -4,6 +4,7 @@ var MultiReporter = require('./reporters/multi')
 var baseReporterDecoratorFactory = require('./reporters/base').decoratorFactory
 var SourceMapConsumer = require('source-map').SourceMapConsumer
 var WeakMap = require('core-js/es6/weak-map')
+var _ = require('./helper')._
 
 var createErrorFormatter = function (basePath, emitter, SourceMapConsumer) {
   var lastServedFiles = []
@@ -39,10 +40,19 @@ var createErrorFormatter = function (basePath, emitter, SourceMapConsumer) {
     }
   }())
 
-  return function (msg, indentation) {
+  return function (input, indentation) {
+    indentation = _.isString(indentation) ? indentation : ''
+    if (_.isError(input)) {
+      input = input.message
+    } else if (_.isEmpty(input)) {
+      input = ''
+    } else if (!_.isString(input)) {
+      input = JSON.stringify(input, null, indentation)
+    }
+
     // remove domain and timestamp from source files
     // and resolve base path / absolute path urls into absolute path
-    msg = (msg || '').replace(URL_REGEXP, function (_, prefix, path, __, ___, line, ____, column) {
+    var msg = input.replace(URL_REGEXP, function (_, prefix, path, __, ___, line, ____, column) {
       if (prefix === 'base') {
         path = basePath + path
       }

test/unit/reporter.spec.js

@@ -11,9 +11,6 @@ describe('reporter', () => {
     m = loadFile(path.join(__dirname, '/../../lib/reporter.js'))
   })
 
-  // ==============================================================================
-  // formatError() [PRIVATE]
-  // ==============================================================================
   describe('formatError', () => {
     var emitter
     var formatError = emitter = null
@@ -31,6 +28,22 @@ describe('reporter', () => {
       expect(formatError(null)).to.equal('\n')
     })
 
+    it('should handle arbitrary error objects', () => {
+      expect(
+        formatError({hello: 'world'})
+      ).to.equal(
+        JSON.stringify({hello: 'world'}) + '\n'
+      )
+    })
+
+    it('should handle error objects', () => {
+      expect(
+        formatError(new Error('fail'))
+      ).to.equal(
+        'fail\n'
+      )
+    })
+
     it('should remove domain from files', () => {
       expect(formatError('file http://localhost:8080/base/usr/a.js and http://127.0.0.1:8080/base/home/b.js')).to.be.equal('file /usr/a.js and /home/b.js\n')
     })