Updated e2e tests to load configuration from a file

LEARNER-509

Makefile

@@ -36,6 +36,7 @@ requirements.js:
 	$(NODE_BIN)/bower install --allow-root
 
 requirements: requirements.js
+	pip install -r e2e/requirements.txt --exists-action w
 	pip install -r requirements/local.txt --exists-action w
 
 production-requirements: requirements.js

e2e/config.py

 import os
+from os.path import dirname, join
+
+from dotenv import load_dotenv
 
 from e2e.utils import str2bool
 
+# Load environment variables from an external file. Existing values will take precedence. The variables will be read
+# later to configure the tests. See https://github.com/theskumar/python-dotenv.
+dotenv_path = os.environ.get('DOTENV_PATH', join(dirname(__file__), '.env'))
+load_dotenv(dotenv_path)
+
 OAUTH_ACCESS_TOKEN_URL = os.environ.get('OAUTH_ACCESS_TOKEN_URL')
 OAUTH_CLIENT_ID = os.environ.get('OAUTH_CLIENT_ID')
 OAUTH_CLIENT_SECRET = os.environ.get('OAUTH_CLIENT_SECRET')

e2e/requirements.txt

@@ -4,4 +4,5 @@ ddt==1.1.1
 django-nose==1.4.4
 edx-rest-api-client==1.7.1
 nose-ignore-docstring==0.2
+python-dotenv==0.6.4
 selenium==3.4.2