feat: do not preprocess files if coverage reporter is not used

Closes #7

lib/preprocessor.js

@@ -1,9 +1,16 @@
 var istanbul = require('istanbul');
 
-var createCoveragePreprocessor = function(logger, basePath) {
+var createCoveragePreprocessor = function(logger, basePath, reporters) {
   var log = logger.create('preprocessor.coverage');
   var instrumenter = new istanbul.Instrumenter();
 
+  // if coverage reporter is not used, do not preprocess the files
+  if (reporters.indexOf('coverage') === -1) {
+    return function(content, _, done) {
+      done(content);
+    };
+  }
+
   return function(content, file, done) {
     log.debug('Processing "%s".', file.originalPath);
 
@@ -17,6 +24,6 @@ var createCoveragePreprocessor = function(logger, basePath) {
   };
 };
 
-createCoveragePreprocessor.$inject = ['logger', 'config.basePath'];
+createCoveragePreprocessor.$inject = ['logger', 'config.basePath', 'config.reporters'];
 
 module.exports = createCoveragePreprocessor;

test/preprocessor.spec.coffee

@@ -0,0 +1,52 @@
+vm = require 'vm'
+util = require 'util'
+
+describe 'preprocessor', ->
+  createPreprocessor = require '../lib/preprocessor'
+
+  ORIGINAL_CODE = '''
+  if (a) {
+    something();
+  } else {
+    other();
+  }
+  '''
+
+
+  mockLogger = create: ->
+    error: -> throw new Error(util.format.apply util, arguments)
+    warn: -> null
+    info: -> null
+    debug: -> null
+
+  # TODO(vojta): refactor this somehow ;-) it's copy pasted from lib/file-list.js
+  File = (path, mtime) ->
+    @path = path
+    @originalPath = path
+    @contentPath = path
+    @mtime = mtime
+    @isUrl = false
+
+
+  it 'should not do anything if coverage reporter is not used', (done) ->
+    process = createPreprocessor mockLogger, null, ['dots', 'progress']
+    file = new File '/base/path/file.js'
+
+    process ORIGINAL_CODE, file, (preprocessedCode) ->
+      expect(preprocessedCode).to.equal ORIGINAL_CODE
+      expect(file.path).to.equal '/base/path/file.js'
+      done()
+
+
+  it 'should preprocess the code', (done) ->
+    process = createPreprocessor mockLogger, '/base/path', ['coverage', 'progress']
+    file = new File '/base/path/file.js'
+
+    process ORIGINAL_CODE, file, (preprocessedCode) ->
+      sandbox =
+        a: true
+        something: ->
+
+      vm.runInNewContext preprocessedCode, sandbox
+      expect(sandbox.__coverage__).to.have.ownProperty './file.js'
+      done()

test/reporter.spec.coffee

@@ -1,22 +1,3 @@
-# TODO(vojta): extract this into a separate file
-sinon = require 'sinon'
-chai = require 'chai'
-
-# publish globals that all specs can use
-global.expect = chai.expect
-global.should = chai.should()
-global.sinon = sinon
-
-# chai plugins
-chai.use(require 'sinon-chai')
-
-beforeEach ->
-  global.sinon = sinon.sandbox.create()
-
-afterEach ->
-  global.sinon.restore()
-
-
 #==============================================================================
 # lib/reporters/Coverage.js module
 #==============================================================================