function runTestServer(testsFolder, port) {
  return createTestEnv(testsFolder).then(function(tempPath) {
    if (killServer) {
      throw new Error('Debug server start inhibited');
    }
    started = true;
    connect.server({
      livereload: true,
      port: port,
      root: tempPath
    });
  });
}
@param {string} testsFolder The folder that contains the test to be included
    in the server.
@param {number} port
@return {!IThenable}