《Flask Web开发》第七章，学到最后程序能够成功运行，但是进行单元测试却报错。

相关文件app__init__.py代码：

from flask import Flask, render_template
from flask_bootstrap import Bootstrap
from flask_mail import Mail
from flask_moment import Moment
from flask_sqlalchemy import SQLAlchemy
from config import config

bootstrap = Bootstrap()
mail = Mail()
moment = Moment()
db = SQLAlchemy()

def create_app(config_name):
    app = Flask(__name__)
    app.config.from_object(config[config_name])
    config[config_name].init_app(app)
    
    bootstrap.init_app(app)
    mail.init_app(app)
    moment.init_app(app)
    db.init_app(app)
    
    from .main import main as main_blueprint
    app.register_blueprint(main_blueprint)             #注册蓝本
    
    return app

teststest_basics.py文件代码：

import unittest
from flask import current_app
from app import create_app, db

class BasicsTestCase(unittest.TestCase):
    def setUp(self):
        self.app = create_app('testing')
        self.app_context = self.app.app_context()
        self.app_context.push()
        db.create_all()
        
    def tearDown(self):
        db.session.remove()
        db.drop_all()
        self.app_context.pop()
        
    def test_app_exists(self):
        self.assertFalse(current_app is None)
        
    def test_app_is_testing(self):
        self.assertTrue(current_app.config['TESTING'])

运行python manage.py runserver 没有问题，但是进行单元测试就失败了。网上查了一下，查不到太多的错误解析，求解？？？