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Python Django Basics Test Time Model Tests

Posted by Daniel Wu
Daniel Wu
4,349 Points

Why is my test failing?

from django.test import TestCase
from django.utils import timezone

from .models import Course, Step


class CourseModelTests(TestCase):
    def test_course_creation(self):
        course = Course.objects.create(
            title="Python Regular Expressions",
            description="Learn to write regular expressions in Python"
        )
        now = timezone.now()
        self.assertLess(course.created_at, now)


class StepModelTests(TestCase):
    def setUp(self):
        self.course = Course.objects.create(
            title="Python Testing",
            description="Learn to write tests in Python"
        )

    def test_step_creation(self):
        step = Step.objects.create(
            title="Introduction to Doctests",
            description="Learn to write tests in your docstrings.",
            course=self.course
        )
        self.assertIn(step, self.course.step_set.all())

OUTPUT

python manage.py test
Creating test database for alias 'default'...
F.
======================================================================
FAIL: test_course_creation (courses.tests.CourseModelTests)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "C:\Users\AJ\learning_site2\courses\tests.py", line 14, in test_course_creation
    self.assertLess(course.created_at, now)
AssertionError: datetime.datetime(2017, 3, 24, 5, 45, 9, 38206, tzinfo=<UTC>) not less than datetime.datetime(2017, 3, 24, 5, 45, 9, 38206, tzinfo=<UTC>)

----------------------------------------------------------------------
Ran 2 tests in 0.005s

FAILED (failures=1)
Destroying test database for alias 'default'...
Amin Ruhul
Amin Ruhul
Courses Plus Student 4,762 Points
Amin Ruhul
Amin Ruhul
Courses Plus Student 4,762 Points

The reason is you are created course and just taking that time as created_at and then comparing as less than to current time which is wrong.

You can do in two ways:

  1. Instead of assertLess use assertEqual self.assertLess(course.created_at, now) to self.assertEqual(course.created_at, now) or
  2. add few mins with now so that it becomes greater than now
Daniel Wu
Daniel Wu
4,349 Points

Thank you Amin! Unfortunately I used AssertEqual and received a similar failure...

C:\Users\AJ\learning_site2>python manage.py test
Creating test database for alias 'default'...
F....
======================================================================
FAIL: test_course_creation (courses.tests.CourseModelTests)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "C:\Users\AJ\learning_site2\courses\tests.py", line 17, in test_course_creation
    self.assertLess(course.created_at, now)
AssertionError: datetime.datetime(2017, 3, 24, 15, 8, 27, 867985, tzinfo=<UTC>) not less than datetime.datetime(2017, 3, 24, 15, 8, 27, 867985, tzinfo=<UTC>)

----------------------------------------------------------------------
Ran 5 tests in 0.060s

FAILED (failures=1)
Destroying test database for alias 'default'...

from django.core.urlresolvers import reverse
#get the name of the url, what's the route it goes to, and the view

from django.test import TestCase
from django.utils import timezone

from .models import Course, Step


class CourseModelTests(TestCase):
    def test_course_creation(self):
        course = Course.objects.create(
            title="Python Regular Expressions",
            description="Learn to write regular expressions in Python"
        )
        now = timezone.now()
        self.assertEqual(course.created_at, now)


class StepModelTests(TestCase):
    def setUp(self):
        self.course = Course.objects.create(
            title="Python Testing",
            description="Learn to write tests in Python"
        )

    def test_step_creation(self):
        step = Step.objects.create(
            title="Introduction to Doctests",
            description="Learn to write tests in your docstrings.",
            course=self.course
        )
        self.assertIn(step, self.course.step_set.all())


class CourseViewsTests(TestCase):
    def setUp(self): 
    #setup method to create things before writing tests
        self.course = Course.objects.create(
            title="Python Testing",
            description="Learn to write tests in Python"
        )
        self.course2 = Course.objects.create(
            title="New Course",
            description="A new course"
        )
        self.step = Step.objects.create(
            title="Introduction to Doctests",
            description="Learn to write tests in your docstrings.",
            course=self.course
        )

    def test_course_list_view(self):
        resp = self.client.get(reverse('courses:list'))
        #self.client is a webbrowser that makes web requests to the url 
        #and give you status code
        #reverse the namespace list url
        #make sure it's 200.

        self.assertEqual(resp.status_code, 200)
        self.assertIn(self.course, resp.context['courses'])
        #make sure the views are in the contexts.
        self.assertIn(self.course2, resp.context['courses'])
        self.assertTemplateUsed(resp, 'courses/course_list.html')
        self.assertContains(resp, self.course.title)
        #makes sure the page contains the title

    def test_course_detail_view(self):
        resp = self.client.get(reverse('courses:detail',
                                       kwargs={'pk': self.course.pk}))
        self.assertEqual(resp.status_code, 200)
        self.assertEqual(self.course, resp.context['course'])

    def test_step_detail(self):
        resp = self.client.get(reverse('courses:step', kwargs={
                    'course_pk': self.course.pk,
                    'step_pk': self.step.pk}))
        self.assertEqual(resp.status_code, 200)
        self.assertEqual(self.step, resp.context['step'])

5 Answers

Juan Ignacio Beloqui
Juan Ignacio Beloqui
3,064 Points
Juan Ignacio Beloqui
Juan Ignacio Beloqui
3,064 Points

The problem is that the record you have created and the variable you use to compare with are the same. It should be corrected in the videos i guess. I solved it like this:

    self.assertLessEqual(course.created_at, now)

Look at the assert: is not assertLess but instead is an assertLessEqual which verifies if a is less or equal than b

Brady Rothrock
Brady Rothrock
2,709 Points

I just used assertLess and was able to get it to work. 

self.assertLess(course.created_at, now)

If you needed to use assertLessEqual then I wonder if it has to do with settings on individual machines or venvs of how precise the time values are stored.

Amin Ruhul
PLUS
Amin Ruhul
Courses Plus Student 4,762 Points
Amin Ruhul
Amin Ruhul
Courses Plus Student 4,762 Points

I guess error is different. You have some typo error

TypeError: unsupported operand type(s) for +: 'datetime.datetime' and 'int'

I recommend to have a look error and debug it.

Daniel Wu
Daniel Wu
4,349 Points

Just updated the correct error

Dillon Reyna
Dillon Reyna
9,531 Points
Dillon Reyna
Dillon Reyna
9,531 Points

So the above code worked for me, but I have no idea why.

What is "step_set" and when did we make this?

Tanja Riet
Tanja Riet
10,803 Points
Tanja Riet
Tanja Riet
10,803 Points

I would use import (from datetime import timedelta ) to be sure that there is a real time difference.

class CourseModelTests(TestCase): def test_course_creation(self): course = Course.objects.create(title='Python ',description='Learn to write regs') now = timezone.now() + timedelta(seconds=2) self.assertLess(course.created_at,now)

Amin Ruhul
PLUS
Amin Ruhul
Courses Plus Student 4,762 Points
Amin Ruhul
Amin Ruhul
Courses Plus Student 4,762 Points

Your error still saying your are using assertLess ``Traceback (most recent call last): File "C:\Users\AJ\learning_site2\courses\tests.py", line 17, in test_course_creation self.assertLess(course.created_at, now) AssertionError: datetime.datetime(2017, 3, 24, 15, 8, 27, 867985, tzinfo=<UTC>) not less than datetime.datetime(2017, 3, 24, 15, 8, 27, 867985, tzinfo=<UTC>)