Add environ package to integration tests

This makes it easiert to manage environment variables in the tests.
With this we can configure them from tox.

tests/utils.py

-import os
 import unittest
 from urllib.parse import urljoin
 
+import environ
 import requests
 
-_DEFAULT_BASE_URL = 'http://hubapp'
-_DEFAULT_ADMIN_USERNAME = 'admin'
-_DEFAULT_ADMIN_PASSWORD = 'password'
+test_env = environ.FileAwareEnv(
+    SERVE_API=(bool, False),
+    SERVE_BACKOFFICE=(bool, False),
+    SERVE_FRONTEND=(bool, False),
+    BASE_URL=(str, 'http://hubapp'),
+    DJANGO_CREATE_ADMIN_USERNAME=(
+        str,
+        'admin',
+    ),
+    DJANGO_CREATE_ADMIN_PASSWORD=(str, 'password'),
+    API_BASE_URL=(str, '/api'),
+    BACKOFFICE_BASE_URL=(str, '/backoffice'),
+    PLAINUI_BASE_URL=(str, ''),
+)
 
 
 class BaseUrlSession(requests.Session):
@@ -28,7 +39,7 @@ class HubTestCase(unittest.TestCase):
         super().__init__(*args, **kwargs)
 
         # get base URL from environment variable
-        self.base_url = os.getenv('BASE_URL', _DEFAULT_BASE_URL)
+        self.base_url = test_env('BASE_URL')
 
         # ensure base_url ends with a slash
         if not self.base_url.endswith('/'):
@@ -38,11 +49,11 @@ class HubTestCase(unittest.TestCase):
 
     def setUp(self, *args, **kwargs):
         super().setUp(*args, **kwargs)
-        if self.require_api and os.getenv('SERVE_API') not in ['y', 'Y', 'yes']:
+        if self.require_api and not test_env('SERVE_API'):
             self.skipTest('environment: SERVE_API=no')
-        if self.require_backoffice and os.getenv('SERVE_BACKOFFICE') not in ['y', 'Y', 'yes']:
+        if self.require_backoffice and not test_env('SERVE_BACKOFFICE'):
             self.skipTest('environment: SERVE_BACKOFFICE=no')
-        if self.require_frontend and os.getenv('SERVE_FRONTEND') not in ['y', 'Y', 'yes']:
+        if self.require_frontend and not test_env('SERVE_FRONTEND'):
             self.skipTest('environment: SERVE_FRONTEND=no')
 
     def tearDown(self, *args, **kwargs):
@@ -73,11 +84,7 @@ class HubApiTestCase(HubTestCase):
 
         try:
             session = BaseUrlSession(base_url=self.base_url)
-            login_success = self.api_login(
-                session,
-                username=os.getenv('DJANGO_CREATE_ADMIN_USERNAME', _DEFAULT_ADMIN_USERNAME),
-                password=os.getenv('DJANGO_CREATE_ADMIN_PASSWORD', _DEFAULT_ADMIN_PASSWORD),
-            )
+            login_success = self.api_login(session, username=test_env('DJANGO_CREATE_ADMIN_USERNAME'), password=test_env('DJANGO_CREATE_ADMIN_PASSWORD'))
 
             if login_success:
                 self._admin_session = session