feat: add a default config and normalize outputFile path

We used to do this in Karma's config, but it really belongs here.

Author: vojtajina

lib/reporter.js

@@ -39,9 +39,9 @@ Store.mix(BasePathStore, {
 // TODO(vojta): inject only what required (config.basePath, config.coverageReporter)
 var CoverageReporter = function(rootConfig, helper, logger) {
   var log = logger.create('coverage');
-  var config = rootConfig.coverageReporter;
+  var config = rootConfig.coverageReporter || {};
   var basePath = rootConfig.basePath;
-  var outDir = config.dir;
+  var outDir = helper.normalizeWinPath(path.resolve(basePath, config.dir || 'coverage'));
   var reporters = config.reporters;
 
   if (!helper.isDefined(reporters)) {
@@ -82,7 +82,7 @@ var CoverageReporter = function(rootConfig, helper, logger) {
     }
 
     pendingFileWritings++;
-    helper.mkdirIfNotExists(path.resolve(outDir), function() {
+    helper.mkdirIfNotExists(outDir, function() {
       var now = dateformat(new Date(), 'yyyymmdd_HHMMss');
       var name = 'coverage-' + browser.name + '-' + now + '.json';
       fs.writeFile(path.join(outDir, name), JSON.stringify(collector.getFinalCoverage()), 'utf8', function(err) {
@@ -114,7 +114,7 @@ var CoverageReporter = function(rootConfig, helper, logger) {
                 basePath : basePath
               })
             });
-            var reporter = istanbul.Report.create(reporterConfig.type, options);
+            var reporter = istanbul.Report.create(reporterConfig.type || 'html', options);
             try {
               reporter.writeReport(collector, true);
             } catch (e) {