django-externaltestserver 0.2.0

Run your Django selenium tests against an external server

# `django-externaltestserver`
[](https://pypi.python.org/pypi/django-externaltestserver)
[](https://travis-ci.org/saulshanabrook/django-externaltestserver)

## What?

Allows you to easily run selenium tests against an external server. This comes
in two. The first is a drop in replacement for
[`LiveServerTestCase`](https://docs.djangoproject.com/en/1.8/topics/testing/tools/#liveservertestcase)
that will not start a server in the background.

The second is the `livetestserver` management command which allows you to run
a Django server in a seperate process.

## How?
1. `pip install django-externaltestserver`.
2. Set `EXTERNAL_TEST_SERVER` in your settings
3. Change test cases to inherit from
`externaltestserver.ExternalLiveServerTestCase` instead of
`LiveServerTestCase`.
4. (optional) Add `externaltestserver` to `INSTALLED_APPS` to run
`python manage.py livetestserver <port> [--static]` in another process.

## Why?

### External Server
We have a CI system that pushes to a staging server after all tests pass.
We wanted to re-run our selenium test against the staging server, to make
sure there are no regressions moving from a dev to a staging environment.

To do this, we just have to set the `EXTERNAL_TEST_SERVER`
setting to our staging server (like `http://magicapp-staging.herokuapp.com/`)
and make sure our integration tests inherit from `externaltestserver.ExternalLiveServerTestCase`
so that they get the correct `live_server_url`.


### Docker

#### Problem

Testing Selenium in Django with Docker is
[not obvious](http://stackoverflow.com/questions/32408429/running-django-tests-with-selenium-in-docker).

The problem is that there is a circular dependency between the testing
container and the selenium container. The test container needs to access
selenium in order to send commands and recieve responses. The selenium
container needs to access the testing container, in order to hit the server.


You might think we could represent this in our `docker-compose.yml`:

```yaml
db:
image: postgres
test:
build: .
command: python manage.py test
links:
- db
- selenium
selenium:
image: selenium/standalone-chrome
ports:
- "4444:4444"
- "5900:5900"
links:
- test
```

But alas `ERROR: Circular import between test and selenium and db`.

I was previously using
[an alternative solution](https://github.com/docker/compose/issues/1991#issuecomment-138139493),
by placing the the `test` container in the same network as the `selenium`
container, so that they could access each other.


```yaml
db:
image: postgres
test:
build: .
command: python manage.py test
links:
- db
net: "container:selenium"
selenium:
image: selenium/standalone-chrome
ports:
- "4444:4444"
- "5900:5900"
```

This stopped working with Docker Compose 1.5.0 / Docker 1.9.0 with
`ERROR: Conflicting options: --net=container can't be used with links. This would result in undefined behavior`.

#### Solution

Instead we break up the test command into
two seperate Docker containers. One handles serving the app, the other just runs the tests.


This way there are no cyclical dependencies.

```yaml
db:
image: postgres:9.5
test:
build: .
# sleep because https://github.com/docker/compose/issues/374#issuecomment-156546513
command: bash -c "sleep 5; python manage.py test --keepdb"
links:
- db
- selenium
environment:
- EXTERNAL_TEST_SERVER=http://livetestserver:8000/
- SELENIUM_HOST=http://selenium:4444/wd/hub
selenium:
image: selenium/standalone-chrome:2.48.2
links:
- livetestserver
livetestserver:
build: .
# sleep because https://github.com/docker/compose/issues/374#issuecomment-156546513
command: bash -c "sleep 5; python manage.py livetestserver 8000 --static"
expose:
- "8000"
links:
- db

```

Then we just tell our external live tests to use the other container :

```python
# settings.py
import os

EXTERNAL_TEST_SERVER = os.environ.get('EXTERNAL_TEST_SERVER', None)
```

And make sure we are `externaltestserver.ExternalLiveServerTestCase`
and accesing the right selenium server:

```python
# test_integration.py
import os

from selenium import webdriver
from selenium.webdriver.common.desired_capabilities import DesiredCapabilities
from externaltestserver import ExternalLiveServerTestCase

from items.models import Item


class IntegrationTest(ExternalLiveServerTestCase):
def setUp(self):
self.browser = webdriver.Remote(
command_executor=os.environ['SELENIUM_HOST'],
desired_capabilities=DesiredCapabilities.CHROME
)

def test_item_count(self):
Item.objects.create()
# here self.live_server_url == settings.conf.EXTERNAL_TEST_SERVER == "http://testserver:8000/"
self.browser.get(self.live_server_url)
self.assertIn("1", self.browser.page_source)
```

Then we can run all the tests simply with `docker-compose run test`.


## Development

First choose what python and django versions you wanna test on:

```bash
sed -e 's/${PYTHON_VERSION}/3.5/g' -e 's/${DJANGO_VERSION}/1.8/g' Dockerfile.tmpl > Dockerfile
```

Then run the tests:

```bash
docker-compose run test
```


To deploy a new version:

```
# change version in setup.py
python setup.py publish
git tag <version number>
git push --tags
```