Refactor tasks/test.js to be more modular.

This way the main functionality of the script can be reused in the
tasks/test-coverage.js script, which has to run the testsuite as well.

tasks/test.js

@@ -37,10 +37,11 @@ function listen(min, max, server, callback) {
 }
 
 
-/**
+function runTests(includeCoverage, callback) {
+  /**
    * Create the debug server and run tests.
    */
-serve.createServer(function(err, server) {
+  serve.createServer(function(err, server) {
     if (err) {
       process.stderr.write(err.message + '\n');
       process.exit(1);
@@ -51,24 +52,35 @@ serve.createServer(function(err, server) {
         process.stderr.write('Server failed to start: ' + err.message + '\n');
         process.exit(1);
       }
-
       var address = server.address();
       var url = 'http://' + address.address + ':' + address.port;
       var args = [
-      path.join(__dirname,
-          '../node_modules/mocha-phantomjs/lib/mocha-phantomjs.coffee'),
+        path.join(
+          __dirname,
+          '../node_modules/mocha-phantomjs/lib/mocha-phantomjs.coffee'
+        ),
         url + '/test/index.html'
       ];
 
-    if (process.argv.length > 2 && process.argv[2] === 'istanbul') {
+      if (includeCoverage) {
         args.push('spec', '{"hooks": "' +
           path.join(__dirname, '../test/phantom_hooks.js') + '"}');
       }
 
       var child = spawn(phantomjs.path, args, {stdio: 'inherit'});
       child.on('exit', function(code) {
+        callback(code);
+      });
+    });
+  });
+}
+
+if (require.main === module) {
+  runTests(false, function(code){
     process.exit(code);
   });
-  });
+}
+
+module.exports = runTests;
+
 
-});