Test Flask render_template() context

Question

I have a Flask route that looks like this:

@app.route(\'/\')                                                                 
def home():                             


        

Answer 1

You can use the assert_template_used method of TestCase provided by flask-testing.

from flask.ext.testing import TestCase

class MyTest(TestCase):

    def create_app(self):
        return myflaskapp

    def test_greeting(self):
        self.app.get('/')
        self.assert_template_used('hello.html')
        self.assert_context("greeting", "hello")

The method create_app must provide your flask app.

Answer 2

Flask official documentation suggests that you use the template_rendered signal (available since version 0.6) for unit-testing your templates and the variables used to render it.

For example, here is a helper context manager that can be used in a unittest to determine which templates were rendered and what variables were passed to the template:

from flask import template_rendered
from contextlib import contextmanager

@contextmanager
def captured_templates(app):
    recorded = []
    def record(sender, template, context, **extra):
        recorded.append((template, context))
    template_rendered.connect(record, app)
    try:
        yield recorded
    finally:
        template_rendered.disconnect(record, app)

This can now easily be paired with a test client:

with captured_templates(app) as templates:
    rv = app.test_client().get('/')
    assert rv.status_code == 200
    assert len(templates) == 1
    template, context = templates[0]
    assert template.name == 'index.html'
    assert len(context['items']) == 10

Answer 3

My suggestion would be to take a look at the Flask documentation for testing.

Using the docs as a guide you should be able to set up a test case that can check the contents of the response.

import unittest
import yourappname

class MyAppTestCase(unittest.TestCase):
    def setUp(self):
        self.app = yourappname.app.test_client()

    def test_greeting(self):
        rv = self.app.get('/')
        self.assertIn('hello', rv.data)

where yourappname is the name of your app/project.

Answer 4

You may want to use Jinja setup in your Html page, pass the variable to the page and see if updated.

http://flask.pocoo.org/docs/0.11/templating/#jinja-setup

http://jinja.pocoo.org/

As an example:

flask template

@app.route('/')                                                                 
def home():                                                                                                                  
    return render_template(                                                     
        'home.html',                                                            
        greetingDictionary = {"greeting": "hello" , "forthoseabouttorock" :"wesaluteyou" }                                       
    )   

html page

{% for key in greetingDictionary %}
<h1>{{key}}</h1>
<p>{{greetingDictionary[key]}}</p>
{% endfor %}