python -m venv venv
source venv/bin/activate
pip install flask

|-activity
  |-app/
    |-templates/
    |-static/
    |-main/
      |-__init__.py
      |-errors.py
      |-forms.py
      |-views.py
    |-__init__.py
    |-email.py
    |-models.py
  |-migrations/
  |-tests/
    |-__init__.py
    |-test*.py
  |-venv/
  |-requirements.txt
  |-config.py
  |-activity.py


mkdir {app,migrations,tests}
mkdir app/{templates,static,main}
touch requirements.txt
touch config.py
touch activity.py
touch app/__init__.py
touch app/main/__init__.py

import os
basedir = os.path.abspath(os.path.dirname(__file__))

class Config:
    SECRET_KEY = os.environ.get('SECRET_KEY') or 'hard to guess string'
    MAIL_SERVER = os.environ.get('MAIL_SERVER', 'smtp.googlemail.com')
    MAIL_PORT = int(os.environ.get('MAIL_PORT', '587'))
    MAIL_USE_TLS = os.environ.get('MAIL_USE_TLS', 'true').lower() in \
        ['true', 'on', '1']
    MAIL_USERNAME = os.environ.get('MAIL_USERNAME')
    MAIL_PASSWORD = os.environ.get('MAIL_PASSWORD')
    ACTIVITY_MAIL_SUBJECT_PREFIX = '[Activity]'
    ACTIVITY_MAIL_SENDER = 'Activity Admin <activity@example.com>'
    ACTIVITY_ADMIN = os.environ.get('ACTIVITY_ADMIN')
    SQLALCHEMY_TRACK_MODIFICATIONS = False

    @staticmethod
    def init_app(app):
        pass

class DevelopmentConfig(Config):
    DEBUG = True
    SQLALCHEMY_DATABASE_URI = os.environ.get('DEV_DATABASE_URL') or \
        'sqlite:///' + os.path.join(basedir, 'data-dev.sqlite')

class TestingConfig(Config):
    TESTING = True
    SQLALCHEMY_DATABASE_URI = os.environ.get('TEST_DATABASE_URL') or \
        'sqlite://'

class ProductionConfig(Config):
    SQLALCHEMY_DATABASE_URI = os.environ.get('DATABASE_URL') or \
        'sqlite:///' + os.path.join(basedir, 'data.sqlite')

config = {
    'development': DevelopmentConfig,
    'testing': TestingConfig,
    'production': ProductionConfig,

    'default': DevelopmentConfig
}

dist: xenial   # required for Python >= 3.7
language: python
python:
  - "3.7"
# command to install dependencies
install:
  - pip install -r requirements.txt
# command to run tests
script:
  - pytest

import math

def test_sqrt():
   num = 25
   assert math.sqrt(num) == 5

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)

    # attach routes and custom error pages here

    return app

import os
import click
from flask_migrate import Migrate
from app import create_app, db

@pytest.fixture
app = create_app(os.getenv('FLASK_CONFIG') or 'default')
migrate = Migrate(app, db)

@app.shell_context_processor
def make_shell_context():
    return dict(db=db)

@app.route('/')
def hello():
    return "Hello World!"

def __repr__(self):
    return '<Role %r>' % self.name

@property
def password(self):
    raise AttributeError('password is not a readable attribute')

@password.setter
def password(self, password):
    self.password_hash = generate_password_hash(password)

def verify_password(self, password):
    return check_password_hash(self.password_hash, password)

def __repr__(self):
    return '<User %r>' % self.username

def test_no_password_getter(self):
    u = User(password = 'cat')
    with self.assertRaises(AttributeError):
        u.password

def test_password_verification(self):
    u = User(password = 'cat')
    self.assertTrue(u.verify_password('cat'))
    self.assertFalse(u.verify_password('dog'))

def test_password_salts_are_random(self):
    u = User(password='cat')
    u2 = User(password='cat')
    self.assertTrue(u.password_hash != u2.password_hash)

<ul class="nav navbar-nav navbar-right">
    {% if current_user.is_authenticated %}
    <li><a href="{{ url_for('auth.logout') }}">Log Out</a></li>
    {% else %}
    <li><a href="{{ url_for('auth.login') }}">Log In</a></li>
    {% endif %}
</ul>

{% extends "base.html" %}
{% import "bootstrap/wtf.html" as wtf %}

{% block title %}Flasky - Login{% endblock %}

{% block page_content %}
<div class="page-header">
    <h1>Login</h1>
</div>
<div class="col-md-4">
    {{ wtf.quick_form(form) }}
</div>
{% endblock %}

{% endfilter %}

{% filter solution %}
{% extends "base.html" %}

{% block title %}Flasky{% endblock %}

{% block page_content %}
<div class="page-header">
    <h1>Hello, {% if current_user.is_authenticated %}{{ current_user.username }}{% else %}Stranger{% endif %}!</h1>
</div>
{% endblock %}