我从量角器版本4.0.14升级到版本5.0.0，现在我的测试失败了。我使用http-backend-proxy来模拟后端。
测试在4.0.14版本上正常运行，但在升级到5.0版时出现InvalidElementState错误：
E/launcher - invalid element state: Failed to execute 'querySelector' on 'Document': The provided selector is empty.
(Session info: chrome=56.0.2924.87)
(Driver info: chromedriver=2.26.436421 (6c1a3ab469ad86fd49c8d97ede4a6b96a49ca5f6),platform=Mac OS X 10.11.4 x86_64) (WARNING: The server did not provide any stacktrace information)
Command duration or timeout: 36 milliseconds
它失败了（在回应线上）：
afterLoadLogin: function( ) {
httpBackend
.when('POST', this.URL + 'user/login')
.respond( function() {
return [$httpBackend.context.loginStatus, $httpBackend.context.login];
});
}