Flask dummy app with unittest to provide a response to the stackoverflow question at https://stackoverflow.com/q/51252936/3135417

flask_unittesting.py

# application.py

from flask import Flask, render_template_string
from flask_sqlalchemy import SQLAlchemy


db = SQLAlchemy()

class User(db.Model):
    """
    User model
    """
    __tablename__ = 'users'
    user_id = db.Column(db.Integer, primary_key=True)
    first_name = db.Column(db.String(100))
    last_name = db.Column(db.String(100))
    age = db.Column(db.Integer)

    def __init__(self, user_id, first, last, age):
        self.user_id = int(user_id)
        self.first_name = first
        self.last_name = last
        self.age = int(age)

    @classmethod
    def from_string(cls, user_info):
        return cls(*user_info.split("_")[:4])


app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///test_database.db'
app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
app.config['DEBUG'] = True
db.init_app(app)


@app.route('/')
def index():
    msg = """hello! Welcome to the index page. Go to <a href="{{ url_for('welcome') }}">Welcome Page</a>"""
    return render_template_string(msg)


@app.route('/add/<user_string>')
def add_user(user_string):
    try:
        user = User.from_string(user_string)
    except Exception as excp:
        print(excp)
        error_message = """The info provided, {{ info }}, could not be parsed into a user"""
        return render_template_string(error_message, info=user_string)
    if User.query.filter_by(user_id=user.user_id).first():
        msg = """User ID {{ u.user_id }} with name {{ u.first_name + " " + u.last_name }} already exists."""
    else:
        db.session.add(user)
        db.session.commit()
        msg = """User ID {{ u.user_id }} with name {{ u.first_name + " " + u.last_name }} got added to DB."""
    return render_template_string(msg, u=user)


@app.route('/welcome')
def welcome():
    msg = """This actually is the welcome page. <a href="{{ url_for('index') }}">Landing Page</a>"""
    return render_template_string(msg)


if __name__ == '__main__':
  app.run()




# test_app.py
import unittest

from application import app as application, db


TEST_DB = "sqlite:///unittest_database.db"


class BasicTests(unittest.TestCase):
    def setUp(self):
        application.app_context().push()
        application.config['TESTING'] = True
        application.config['DEBUG'] = False
        application.config['SQLALCHEMY_DATABASE_URI'] = TEST_DB
        self.client = application.test_client()
        db.drop_all()
        db.create_all()

        self.assertEqual(application.debug, False)

    def tearDown(self):
        db.session.close()
        db.drop_all()

    def test_welcome_page(self):
        response = self.client.get("/welcome", follow_redirects=True)
        msg = b"""This actually is the welcome page."""
        self.assertEqual(response.status_code, 200)
        self.assertIn(msg, response.data)

    def test_add_user(self):
        response = self.client.get('/add/1_Luke_Kenworthy_18', follow_redirects=True)
        msg = b"""User ID 1 with name Luke Kenworthy got added to DB."""
        self.assertIn(msg, response.data)

    def test_repeated_adds(self):
        self.client.get('/add/1_Luke_Kenworthy_18', follow_redirects=True)
        response = self.client.get('/add/1_Luke_Kenworthy_18', follow_redirects=True)
        msg = b"""User ID 1 with name Luke Kenworthy already exists."""
        self.assertEqual(msg, response.data)



if __name__ == "__main__":
    unittest.main()