Test driven development - when/what to test? - unit-testing

I am trying to get started with TDD but right away I am unsure of when and what I should be testing. The first two tasks in a new project I'm working on are as follows.
1) Receive some JSON formatted data on a REST endpoint and save it in the database. Say the data was several car records -
{
"cars": [{
"make": "ford",
"color": "blue",
"year": "2010",
"for_sale": true
}, {
"make": "bmw",
"color": "black",
"year": "2011",
"for_sale": false
}
] }
So that data arrives at a REST endpoint and I need to save it in the database. Do I need a test for this task and if so what should it look like?
2) Retrieve some records from the database and display them in a view/webpage (i.e. using some templating system). Say the records are the car records above and they should be displayed as follows -
<ul id="cars">
<li id="car-1">
<div><span>Make:</span><span>Ford</span>
</div>
<div><span>Color:</span><span>blue</span>
</div>
<div><span>Year:</span><span>2010</span>
</div>
<div><span>For sale:</span><span>Yes</span>
</div>
</li>
<li id="car-2">
<div><span>Make:</span><span>BMW</span>
</div>
<div><span>Color:</span><span>black</span>
</div>
<div><span>Year:</span><span>2011</span>
</div>
<div><span>For sale:</span><span>No</span>
</div>
</li>
</ul>
So do I need a test for this task and if so what should it look like?

What language, platforms etc are you using? Perhaps we can find some examples for you.
TDD is tricky at first, and a task like this (with Database and web parts) requires testing at several levels.
First divide the task up into single-responsibilities (which probably map to classes) that can be unit tested. For example, a class that takes JSON input, and hydrates an object with properties on it, TDD that class. Database layers are hard to unit test, we normal use the Repository pattern which we then mock when testing other classes.
DB unit testing is hard, so consider an "acceptance" or "integration" test around the database. That might be a test that connects to a real test database, puts in some test data, pulls it out again, and verifies that it looks right. In theory, you then don't even care what database it is, as long as the stuff you store comes out again, you know it's working.
HTML / web testing it also best done at a high level using tools such as selenium webdriver, which allows you to write test code that fires up a real browser, interacts with your page, and asserts that the content/behaviour is as expected.
This stuff is really good learnt by pair programming with someone who already knows it, or perhaps by attending a class or training course. There are also lots of books blogs and tutorials, which let you learn in a sandbox, which is simpler than trying to learn by yourself on a real project, where the pressure to get stuff done is in conflict with learning.
Edit: Java and Play framework.
OK, I don't know the play framework specifically, but from a quick look it probably does the JSON parsing for you if you set it up right, which reduces the json parse function to boilerplate code. There's not a huge amount of value in TDD here, but you can if you want. Similarly, there's an active-record style db layer? So there's not a lot of value in testing code your library has provided (and dbs are hard/impossible/pointless* to unit test) .
Edit:Edit - this turns out to be icky, Apparently Play uses static controller methods which makes it hard to unit test (because you can't inject dependencies - which makes mocking difficult). I'm afraid without doing hours of research I can't help with the specifics, but integration tests are probably the way to go here, which test several of your units of code together, including the DB.
So in summary:
Don't sweat TDD on the boilerplate. Keep boilerplate isolated and thing (ie controllers ONLY do web stuff, then hand over to other classes. Repositories only save and retrieve objects, not rules/decisions/manipulations.
When you start adding more business logic to the guts of your app - keep it isolated in business classes (ie - away from the web or db boilerplate) that you can unit test easily. Definitely TDD this stuff.
Try integration tests across your app to test the DB. Have a real test DB behind your app, use the app to save something, retrieve it, and then assert it's correct.
use something like Selenium to test the web pages.
*delete according to your testing beliefs.

Related

Integration tests CRUD Ember.js

I need to do integration tests for my Ember app, for example in the user template :
<div class="container">
<h1>{{model.firstName}} {{model.lastName}}</h1>
<p>Age: {{model.age}} years old</p>
<p>Job: {{model.job}}</p>
<img src="{{model.image}}" alt="img" id="image">
</div>
I have to test that the list of users is correctly displayed. Is it possible to do so ?
I have never done that and I'm kind of lost here. Would it be something like :
test('it renders all users', function(assert) {
this.set('users', [
{ firstName: 'Tubby'},
{ firstName: 'Spot'},
{ firstName: 'Chester'},
{ firstName: 'Frisky'}
]);
this.render(hbs`{{user users=users}}`);
assert.equal(this.$('.user').length, 4);
});
Even though I read many articles about the integration tests, I still don't understand if it can be used for something that is not a component.
What about redirection ? Let's just say that I have to write an integration test that verifies that the redirection is okay. Can I do that with integration tests ?
Thanks for your help.
It may be worth doing a quick review of the testing options:
Unit tests allow us to test small chunks of code. Things that are easy to test this way would be services, serializers or adapters.
Integration tests are primarily designed to let you test components and the way they work together and interact with users. Things often tested include events of different sorts (clicks, keystrokes, etc) and the way a component reacts to different types of data.
Acceptance tests are often used for testing the integrated whole of your app (pretending to be your user and browsing the site).
Often, checks for redirects would either be an acceptance test. You could also do unit tests (if you have complicated route logic that handles various scenarios that redirect). Testing redirects in an integration test would primarily focus around making sure clicking a button would attempt to redirect somewhere else.
Does that help?
I hope, The below tutorial will help you to understand the test case. The tutorial has examples for all testing(UNIT, Acceptance and Integration).
https://medium.com/#srajas02/ember-test-case-for-a-crud-application-with-mirage-d6d9836bfee2
Source Code: https://github.com/srajas0/ember-test-cases

What are the best practices for testing "different layers" in Django? [closed]

As it currently stands, this question is not a good fit for our Q&A format. We expect answers to be supported by facts, references, or expertise, but this question will likely solicit debate, arguments, polling, or extended discussion. If you feel that this question can be improved and possibly reopened, visit the help center for guidance.
Closed 10 years ago.
I'm NOT new to testing, but got really confused with the mess of recommendations for testing different layers in Django.
Some recommend (and they are right) to avoid Doctests in the model as they are not maintainable...
Others say don't use fixtures, as they are less flexible than helper functions, for instance..
There are also two groups of people who fight for using Mock objects. The first group believe in using Mock and isolating the rest of the system, while another group prefer to Stop Mocking and start testing..
All I have mentioned above, were mostly in regards to testing models. Functional testing is an another story (using test.Client() VS webTest VS etc. )
Is there ANY maintainable, extandible and proper way for testing different layers??
UPDATE
I am aware of Carl Meyer's talk at PyCon 2012..
UPDATE 08-07-2012
I can tell you my practices for unit testing that are working pretty well for my own ends and I'll give you my reasons:
1.- Use Fixtures only for information that is necessary for testing but is not going to change, for example, you need a user for every test you do so use a base fixture to create users.
2.- Use a factory to create your objects, I personally love FactoryBoy (this comes from FactoryGirl which is a ruby library). I create a separate file called factories.py for every app where I save all these objects. This way I keep off the test files all the objects I need which makes it a lot more readable and easy to maintain. The cool thing about this approach is that you create a base object that can be modified if you want to test something else based on some object from the factory. Also it doesn't depend on django so when I migrated these objects when I started using mongodb and needed to test them, everything was smooth. Now after reading about factories it's common to say "Why would I want to use fixtures then". Since these fixtures should never change all the extra goodies from factories are sort of useless and django supports fixtures very well out of the box.
3.- I Mock calls to external services, because these calls make my tests very slow and they depend on things that have nothing to do with my code being right or wrong. for example, if I tweet within my test, I do test it to tweet rightly, copy the response and mock that object so it returns that exact response every time without doing the actual call. Also sometimes is good to test when things go wrong and mocking is great for that.
4.- I use an integration server (jenkins is my recommendation here) which runs the tests every time I push to my staging server and if they fail it sends me an email. This is just great since it happens to me a lot that I break something else in my last change and I forgot to run the tests. It also gives you other goodies like a coverage report, pylint/jslint/pep8 verifications and there exists a lot of plugins where you can set different statistics.
About your question for testing front end, django comes with some helper functions to handle this in a basic way.
This is what I personally use, you can fire gets, posts, login the user, etc. that's enough for me. I don't tend to use a complete front end testing engine like selenium since I feel it's an overkill to test anything else besides the business layer. I am sure some will differ and it always depends on what you are working on.
Besides my opinion, django 1.4 comes with a very handy integration for in-browser frameworks.
I'll set an example app where I can apply this practices so it is more understandable. Let's create a very basic blog app:
structure
blogger/
__init__.py
models.py
fixtures/base.json
factories.py
tests.py
models.py
from django.db import models
class Blog(models.Model):
user = models.ForeignKey(User)
text = models.TextField()
created_on = models.DateTimeField(default=datetime.now())
fixtures/base.json
[
{
"pk": 1,
"model": "auth.user",
"fields": {
"username": "fragilistic_test",
"first_name": "demo",
"last_name": "user",
"is_active": true,
"is_superuser": true,
"is_staff": true,
"last_login": "2011-08-16 15:59:56",
"groups": [],
"user_permissions": [],
"password": "IAmCrypted!",
"email": "test#email.com",
"date_joined": "1923-08-16 13:26:03"
}
}
]
factories.py
import factory
from blog.models import User, Blog
class BlogFactory(factory.Factory):
FACTORY_FOR = Blog
user__id = 1
text = "My test text blog of fun"
tests.py
class BlogTest(TestCase):
fixtures = ['base'] # loads fixture
def setUp(self):
self.blog = BlogFactory()
self.blog2 = BlogFactory(text="Another test based on the last one")
def test_blog_text(self):
self.assertEqual(Blog.objects.filter(user__id=1).count(), 2)
def test_post_blog(self):
# Lets suppose we did some views
self.client.login(username='user', password='IAmCrypted!')
response = self.client.post('/blogs', {'text': "test text", user='1'})
self.assertEqual(response.status, 200)
self.assertEqual(Blog.objects.filter(text='test text').count(), 1)
def test_mocker(self):
# We will mock the datetime so the blog post was created on the date
# we want it to
mocker = Mock()
co = mocker.replace('datetime.datetime')
co.now()
mocker.result(datetime.datetime(2012, 6, 12))
with mocker:
res = Blog.objects.create(user__id=1, text='test')
self.assertEqual(res.created_on, datetime.datetime(2012, 6, 12))
def tearDown(self):
# Django takes care of this but to be strict I'll add it
Blog.objects.all().delete()
Notice I am using some specific technology for the sake of the example (which haven't been tested btw).
I have to insist, this may not be the standard best practice (which I doubt it exists) but it is working pretty well for me.
I really like the suggestions from #Hassek and want to stress out what an excellent point he makes about the obvious lack of standard practices, which holds true for many of Django's aspects, not just testing, since all of us approach the framework with different concerns in mind, also adding to that the great degree of flexibility we have with designing our applications, we often end up with drastically different solutions that are applicable to the same problem.
Having said that, though, most of us still strive for many of the same goals when testing our applications, mainly:
Keeping our test modules neatly organized
Creating reusable assertion and helper methods, helper functions that reduce the LOC for test methods, to make them more compact and readable
Showing that there is an obvious, systematic approach to how the application components are tested
Like #Hassek, these are my preferences that may directly conflict with the practices that you may be applying, but I feel it's nice to share the things we've proven that work, if only in our case.
No test case fixtures
Application fixtures work great, in cases you have certain constant model data you'd like to guarantee to be present in the database, say a collection of towns with their names and post office numbers.
However, I see this as an inflexible solution for providing test case data. Test fixtures are very verbose, model mutations force you to either go through a lengthy process of reproducing the fixture data or to perform tedious manual changes and maintaining referential integrity is difficult to manually perform.
Additionally, you'll most likely use many kinds of fixtures in your tests, not just for models: you'd like to store the response body from API requests, to create fixtures that target NoSQL database backends, to write have fixtures that are used to populate form data, etc.
In the end, utilizing APIs to create data is concise, readable and it makes it much easier to spot relations, so most of us resort to using factories for dynamically creating fixtures.
Make extensive use of factories
Factory functions and methods are preferable to stomping out your test data. You can create helper factory module-level functions or test case methods that you may want to either reuse
across application tests or throughout the whole project. Particularly, factory_boy, that #Hassek mentions, provides you with the ability to inherit/extend fixture data and do automatic sequencing, which might look a bit clumsy if you'd do it by hand otherwise.
The ultimate goal of utilizing factories is to cut down on code-duplication and streamline how you create test data. I cannot give you exact metrics, but I'm sure if you go through your test methods with a discerning eye you will notice that a large portion of your test code is mainly preparing the data that you'll need to drive your tests.
When this is done incorrectly, reading and maintaining tests becomes an exhausting activity. This tends to escalate when data mutations lead to not-so-obvious test failures across the board, at which point you'll not be able to apply systematic refactoring efforts.
My personal approach to this problem is to start with a myproject.factory module that creates easy-to-access references to QuerySet.create methods for my models and also for any objects I might regularly use in most of my application tests:
from django.contrib.auth.models import User, AnonymousUser
from django.test import RequestFactory
from myproject.cars.models import Manufacturer, Car
from myproject.stores.models import Store
create_user = User.objects.create_user
create_manufacturer = Manufacturer.objects.create
create_car = Car.objects.create
create_store = Store.objects.create
_factory = RequestFactory()
def get(path='/', data={}, user=AnonymousUser(), **extra):
request = _factory.get(path, data, **extra)
request.user = user
return request
def post(path='/', data={}, user=AnonymousUser(), **extra):
request = _factory.post(path, data, **extra)
request.user = user
return request
This in turn allows me to do something like this:
from myproject import factory as f # Terse alias
# A verbose, albeit readable approach to creating instances
manufacturer = f.create_manufacturer(name='Foomobiles')
car1 = f.create_car(manufacturer=manufacturer, name='Foo')
car2 = f.create_car(manufacturer=manufacturer, name='Bar')
# Reduce the crud for creating some common objects
manufacturer = f.create_manufacturer(name='Foomobiles')
data = {name: 'Foo', manufacturer: manufacturer.id)
request = f.post(data=data)
view = CarCreateView()
response = view.post(request)
Most people are rigorous about reducing code duplication, but I actually intentionally introduce some whenever I feel it contributes to test comprehensiveness. Again, the goal with whichever approach you take to factories is to minimize the amount of brainfuck you introduce into the header of each test method.
Use mocks, but use them wisely
I'm a fan of mock, as I've developed an appreciation for the author's solution to what I believe was the problem he wanted to address. The tools provided by the package allow you to form test assertions by injecting expected outcomes.
# Creating mocks to simplify tests
factory = RequestFactory()
request = factory.get()
request.user = Mock(is_authenticated=lamda: True) # A mock of an authenticated user
view = DispatchForAuthenticatedOnlyView().as_view()
response = view(request)
# Patching objects to return expected data
#patch.object(CurrencyApi, 'get_currency_list', return_value="{'foo': 1.00, 'bar': 15.00}")
def test_converts_between_two_currencies(self, currency_list_mock):
converter = Converter() # Uses CurrencyApi under the hood
result = converter.convert(from='bar', to='foo', ammount=45)
self.assertEqual(4, result)
As you can see, mocks are really helpful, but they have a nasty side effect: your mocks clearly show your making assumptions on how it is that your application behaves, which introduces coupling. If Converter is refactored to use something other than the CurrencyApi, someone may not obviously understand why the test method is suddenly failing.
So with great power comes great responsibility--if your going to be a smartass and use mocks to avoid deeply rooted test obstacles, you may completely obfuscate the true nature of your test failures.
Above all, be consistent. Very very consistent
This is the most important point to be made. Be consistent with absolutely everything:
how you organize code in each of your test modules
how you introduce test cases for your application components
how you introduce test methods for asserting the behavior of those components
how you structure test methods
how you approach testing common components (class-based views, models, forms, etc.)
how you apply reuse
For most projects, the bit about how your collaboratively going to approach testing is often overlooked. While the application code itself looks perfect--adhering to style guides, use of Python idioms, reapplying Django's own approach to solving related problems, textbook use of framework components, etc.--no one really makes it an effort to figure out how to turn test code into a valid, useful communication tool and it's a shame if, perhaps, having clear guidelines for test code is all it takes.

Unit Testing basic Controllers

I have a number of simple controller classes that use Doctrine's entity manager to retrieve data and pass it to a view.
public function indexAction() {
$pages = $this->em->getRepository('Model_Page')->findAll();
$this->view->pages = $pages;
}
What exactly should we be testing here?
I could test routing on the action to ensure that's configured properly
I could potentially test that the appropriate view variables are being set, but this is cumbersome
The findAll() method should probably be in a repository layer which can be tested using mock data, but then this constitutes a different type of test and brings us back to the question of
What should we be testing as part of controller tests?
Controller holds core logic for your application. Though simple "index" controller actions don't have any specific functions, those that verify/actively use data and generate viewmodels have pretty much the most functionality of the system.
For example, consider login form. Whenever the login data is posted, controller should validate login/password and return: 1) to index page whenever logins are good. Show welcome,{user} text. 2) to the login page saying that login is not found in db. 3) to the login page saying that password is not found in db.
These three types of outputs make perfect test cases. You should validate that correct viewmodels/views are being sent back to the client with the appropriate actions.
You shouldn't look at a controller like at something mysterious. It's just another code piece, and it's tested as any other code - any complicated logic that gives business-value to the user should be tested.
Also, I'd recommend using acceptance testing with framework like Cucumber to generate meaningful test cases.
Probably the controller is the hardest thing to test, as it has many dependencies. In theory you should test it in full isolation, but as you already seen - it has no sense.
Probably you should start with functional or acceptance test. It tests your controller action in a whole. I agree with previous answer, that you should try acceptance testing tools. But Cucumber is for Ruby, for PHP you can try using Codeception. It makes tests simple and meaningful.
Also on a Codeception page there is an article on how to test sample controllers.

Django tests reliant on other pages/behaviour

I've started writing some tests for my Django app and I'm unsure how best to structure the code.
Say I have a register page and a page for logged in users only.
My first plan was to have an earlier method perform the register and a later method use that login to test the page:
def test_register_page(self):
//send request to register page and check user has been registered correctly
def test_restricted_page(self):
c = Client();
c.login("someUser","pass");
c.post("/someRestrictedPage/");
//Test response
However this means that now one of my tests rely on the other.
The alternatives I see are calling register in setUp() but this still means that the restricted page test relies on the register page working.
I could try creating a new user manually in setup which I also don't like because this isn't testing a user created by the system.
What is the usual pattern for testing this kind of situation?
You are trying to mix together a lot of different functionalities in one test case. A clean design would be having one test case
for user registration and
one for the view.
Having them depend on each other will introduce a lot of dependencies between them - and - if the test fails the error will be even harder to debug. The success of the registration test should be determined through the correct creation of the user instance (so check necessary attributes etc of the user) and not through being able to login on a certain page. Therefore you will need to set up a "correct" user instance for the view test case. This may seem a bit more complicated than necessary, but it will make future maintainance a lot easier.
What you are trying to do is more something like an integration test, which tests a whole system, but before that you should split up your system in functional units and do unit tests on this units!
The smaller and well-defined the single tests are, the easier will be their maintainance and debugging.

Testing Mongoose Node.JS app

I'm trying to write unit tests for parts of my Node app. I'm using Mongoose for my ORM.
I've searched a bunch for how to do testing with Mongoose and Node but not come with anything. The solutions/frameworks all seem to be full-stack or make no mention of mocking stuff.
Is there a way I can mock my Mongoose DB so I can return static data in my tests? I'd rather not have to set up a test DB and fill it with data for every unit test.
Has anyone else encountered this?
I too went looking for answers, and ended up here. This is what I did:
I started off using mockery to mock out the module that my models were in. An then creating my own mock module with each model hanging off it as a property. These properties wrapped the real models (so that child properties exist for the code under test). And then I override the methods I want to manipulate for the test like save. This had the advantage of mockery being able to undo the mocking.
but...
I don't really care enough about undoing the mocking to write wrapper properties for every model. So now I just require my module and override the functions I want to manipulate. I will probably run tests in separate processes if it becomes an issue.
In the arrange part of my tests:
// mock out database saves
var db = require("../../schema");
db.Model1.prototype.save = function(callback) {
console.log("in the mock");
callback();
};
db.Model2.prototype.save = function(callback) {
console.log("in the mock");
callback("mock staged an error for testing purposes");
};
I solved this by structuring my code a little. I'm keeping all my mongoose-related stuff in separate classes with APIs like "save", "find", "delete" and no other class does direct access to the database. Then I simply mock those in tests that rely on data.
I did something similar with the actual objects that are returned. For every model I have in mongoose, I have a corresponding class that wraps it and provides access-methods to fields. Those are also easily mocked.
Also worth mentioning:
mockgoose - In-memory DB that mocks Mongoose, for testing purposes.
monckoose - Similar, but takes a different approach (Implements a fake driver). Monckoose seems to be unpublished as of March 2015.