diff --git a/.coveragerc b/.coveragerc
deleted file mode 100644
index 3334c71..0000000
--- a/.coveragerc
+++ /dev/null
@@ -1,4 +0,0 @@
-[run]
-relative_files = True
-omit = admin_confirm/tests/*
-branch = True
diff --git a/.env b/.env
new file mode 100644
index 0000000..5802fdc
--- /dev/null
+++ b/.env
@@ -0,0 +1,2 @@
+PYTHON_VERSION=3.8
+DJANGO_VERSION=3.1.7
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 3b1ee26..d4fbd19 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -14,47 +14,41 @@ on:
       - created
 
 jobs:
+  lint:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+    - name: wemake-python-styleguide
+      uses: wemake-services/wemake-python-styleguide@0.15.2
+      with:
+        path: admin_confirm
+        reporter: 'github-pr-review'
+      env:
+        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+      continue-on-error: true
+
   test:
     runs-on: ubuntu-latest
     strategy:
       matrix:
         python-version: [3.6, 3.7, 3.8, 3.9]
         django-version: [2.2, 3.0]
+    env:
+      DJANGO_VERSION: ${{ matrix.django-version }}
+      PYTHON_VERSION: ${{ matrix.python-version }}
+      COMPOSE_INTERACTIVE_NO_CLI: 1
     steps:
     - uses: actions/checkout@v2
-    - name: Set up Python ${{ matrix.python-version }}
-      uses: actions/setup-python@v2
-      with:
-        python-version: ${{ matrix.python-version }}
-    - name: Install Django ${{ matrix.django-version }}
+    - name: Build Docker for Python 3.6
+      if: ${{ matrix.python-version == 3.6 }}
       run: |
-        pip install django==${{ matrix.django-version }}
-    - name: Install dependencies
+        export SELENIUM_VERSION=3.141.0
+        docker-compose build
+    - name: Build Docker for other Python versions
+      if: ${{ matrix.python-version != 3.6 }}
       run: |
-        python -m pip install --upgrade pip
-        pip install flake8 pytest
-        if [ -f requirements.txt ]; then pip install -r requirements.txt; fi
-    - name: Lint with flake8
-      run: |
-        # stop the build if there are Python syntax errors or undefined names
-        flake8 . --count --select=E9,F63,F7,F82 --show-source --statistics
-        # exit-zero treats all errors as warnings. The GitHub editor is 127 chars wide
-        flake8 . --count --exit-zero --max-complexity=10 --max-line-length=127 --statistics
-    - name: Unit Test
-      run: |
-        make test
-    - name: Coveralls
-      uses: AndreMiras/coveralls-python-action@develop
-      with:
-        parallel: true
-        flag-name: Unit Test
-
-  integration-test:
-    runs-on: ubuntu-latest
-    steps:
-    - uses: actions/checkout@v2
-    - name: Build Docker
-      run: docker-compose build
+        export SELENIUM_VERSION=4.0.0a7
+        docker-compose build
     - name: Start Docker
       run: docker-compose up -d
     - name: Integration Test
@@ -63,10 +57,9 @@ jobs:
       uses: AndreMiras/coveralls-python-action@develop
       with:
         parallel: true
-        flag-name: Integration Test
 
   coveralls:
-    needs: [test, integration-test]
+    needs: [test]
     runs-on: ubuntu-latest
     steps:
     - name: Coveralls Finished
diff --git a/Dockerfile b/Dockerfile
index d388347..f06a924 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,7 +1,12 @@
-FROM python:3
+ARG PYTHON_VERSION=3.8
+FROM python:${PYTHON_VERSION}
 ENV PYTHONUNBUFFERED=1
 ENV USE_DOCKER=true
 WORKDIR /code
-COPY requirements.txt /code/
-RUN pip install -r requirements.txt
 COPY . /code/
+ARG DJANGO_VERSION="3.1.7"
+RUN pip install django==${DJANGO_VERSION}
+RUN pip install -r requirements.txt
+RUN pip install -e .
+ARG SELENIUM_VERSION="4.0.0a7"
+RUN pip install selenium~=${SELENIUM_VERSION}
diff --git a/README.md b/README.md
index 7aa1232..5ae4eb3 100644
--- a/README.md
+++ b/README.md
@@ -153,6 +153,13 @@ pyenv vituralenv 3.8.0 django-admin-confirm-3.8.0
 
 Now your terminal should have `(django-admin-confirm-3.8.0)` prefix, because `.python-version` should have auto switch your virtual env
 
+Install requirements
+
+```
+pip install -r requirements.txt
+pip install -e .
+```
+
 Run **migrations** and create a superuser and run the server
 
 ```
@@ -237,7 +244,6 @@ pip uninstall django_admin_confirm
 make install-testpypi VERSION=<VERSION>
 ```
 
-Update version in `requirements.txt`
 Add test locally
 
 ```
diff --git a/admin_confirm/admin.py b/admin_confirm/admin.py
index 9286bec..615de0e 100644
--- a/admin_confirm/admin.py
+++ b/admin_confirm/admin.py
@@ -11,7 +11,6 @@ from django.forms import ModelForm
 from admin_confirm.utils import get_admin_change_url, snake_to_title_case
 from django.core.cache import cache
 from django.views.decorators.cache import cache_control
-from django.forms.formsets import all_valid
 from admin_confirm.constants import (
     CACHE_TIMEOUT,
     CONFIRMATION_RECEIVED,
@@ -139,7 +138,7 @@ class AdminConfirmMixin:
                 return [initial_value, new_value]
 
             if initial_value:
-                if new_value == False:
+                if new_value is False:
                     # Clear has been selected
                     return [initial_value.name, None]
                 elif new_value:
@@ -249,7 +248,7 @@ class AdminConfirmMixin:
             if CONFIRM_CHANGE in modified_post:
                 del modified_post[CONFIRM_CHANGE]
 
-            if object_id and not SAVE_AS_NEW in request.POST:
+            if object_id and SAVE_AS_NEW not in request.POST:
                 # Update the obj with the new uploaded files
                 # then pass rest of changes to Django
                 obj = self.model.objects.filter(id=object_id).first()
@@ -287,6 +286,20 @@ class AdminConfirmMixin:
         cache.delete_many(CACHE_KEYS.values())
         return super()._changeform_view(request, object_id, form_url, extra_context)
 
+    def _get_cleared_fields(self, request):
+        """
+        Checks for any ImageField or FileField which have been cleared by user.
+
+        Because the form that is generated by Django for the model, would not have the
+        `<field>-clear` inputs in them, they have to be injected into the hidden form
+        on the confirmation page.
+        """
+        return [
+            input_name.split("-clear")[0]
+            for input_name in request.POST.keys()
+            if input_name.endswith("-clear")
+        ]
+
     def _change_confirmation_view(self, request, object_id, form_url, extra_context):
         # This code is taken from super()._changeform_view
         # https://github.com/django/django/blob/master/django/contrib/admin/options.py#L1575-L1592
@@ -348,10 +361,14 @@ class AdminConfirmMixin:
                 save_action = key
                 break
 
+        cleared_fields = []
         if form.is_multipart():
             cache.set(CACHE_KEYS["post"], request.POST, timeout=CACHE_TIMEOUT)
             cache.set(CACHE_KEYS["object"], new_object, timeout=CACHE_TIMEOUT)
 
+            # Handle when files are cleared - since the `form` object would not hold that info
+            cleared_fields = self._get_cleared_fields(request)
+
         title_action = _("adding") if add_or_new else _("changing")
         context = {
             **self.admin_site.each_context(request),
@@ -368,6 +385,7 @@ class AdminConfirmMixin:
             "save_as_new": SAVE_AS_NEW in request.POST,
             "submit_name": save_action,
             "form": form,
+            "cleared_fields": cleared_fields,
             "formsets": formsets,
             **(extra_context or {}),
         }
diff --git a/admin_confirm/templates/admin/change_confirmation.html b/admin_confirm/templates/admin/change_confirmation.html
index 433c75d..ff21a0b 100644
--- a/admin_confirm/templates/admin/change_confirmation.html
+++ b/admin_confirm/templates/admin/change_confirmation.html
@@ -40,8 +40,11 @@
     {% include "admin/change_data.html" %}
 
     <form {% if form.is_multipart %}enctype="multipart/form-data"{% endif %} method="post" {% if add %}action="{% url opts|admin_urlname:'add'%}" {% else %}action="{% url opts|admin_urlname:'change' object_id|admin_urlquote %}"{% endif %}>{% csrf_token %}
-        <div class="hidden">
+        <div class="hidden" id="hidden-form">
             {{form.as_p}}
+            {% for cleared_field in cleared_fields %}
+                <input type="checkbox" name="{{ cleared_field }}-clear" checked>
+            {% endfor %}
             {% for formset in formsets %}
                 {{ formset.as_p }}
             {% endfor %}
diff --git a/admin_confirm/templatetags/formatting.py b/admin_confirm/templatetags/formatting.py
index 40bdbd2..2f579b4 100644
--- a/admin_confirm/templatetags/formatting.py
+++ b/admin_confirm/templatetags/formatting.py
@@ -1,5 +1,4 @@
 from django import template
-from django.db.models.query import QuerySet
 from django.utils.html import escape
 from django.utils.safestring import mark_safe
 
@@ -16,5 +15,5 @@ def format_change_data_field_value(field_value):
             output += "<li>" + escape(value) + "</li>"
         output += "</ul>"
         return mark_safe(output)
-    except:
+    except Exception:
         return field_value
diff --git a/admin_confirm/tests/README.md b/admin_confirm/tests/README.md
index bb7626e..7304bf5 100644
--- a/admin_confirm/tests/README.md
+++ b/admin_confirm/tests/README.md
@@ -8,6 +8,12 @@ You seem concerned about the stability and reliability of this package. You're p
 
 So if you want to include this package in your production codebase, be aware that AdminConfirmMixin works best with simple unmodified ModelAdmins.
 
+# Probable Issues
+
+These are some areas which might/probably have issues that are not currently tested. Use at your own risk!
+
+- [ ] Saving file/image changes on inlines when confirming change on parent model
+
 ## Save Options
 
 - [x] Save
@@ -71,10 +77,10 @@ Confirmation on inline changes is not a current feature of this project.
 
 Confirmation on add/change of ModelAdmin that includes inlines needs to be tested. Use AdminConfirmMixin with ModelAdmin containing inlines at your own risk.
 
-- [ ] .inlines
-- [ ] .get_inline_instances()
-- [ ] .get_inlines() (New in Django 3.0)
-- [ ] .get_formsets_with_inlines()
+- [x] .inlines
+- [x] .get_inline_instances()
+- [x] .get_inlines() (New in Django 3.0)
+- [ ] .get_formsets_with_inlines() ???
 
 #### Options for inlines
 
diff --git a/admin_confirm/tests/helpers.py b/admin_confirm/tests/helpers.py
index fe80c93..ded48d3 100644
--- a/admin_confirm/tests/helpers.py
+++ b/admin_confirm/tests/helpers.py
@@ -1,6 +1,12 @@
+import socket
+
 from django.core.cache import cache
 from django.test import TestCase, RequestFactory
 from django.contrib.auth.models import User
+from django.test import LiveServerTestCase
+from selenium import webdriver
+from selenium.webdriver.common.desired_capabilities import DesiredCapabilities
+
 
 class AdminConfirmTestCase(TestCase):
     """
@@ -62,16 +68,10 @@ class AdminConfirmTestCase(TestCase):
                 self.assertIn("apple", rendered_content)
 
 
-
-import socket
-from django.test import LiveServerTestCase
-from selenium import webdriver
-from selenium.webdriver.common.desired_capabilities import DesiredCapabilities
-
-
 class AdminConfirmIntegrationTestCase(LiveServerTestCase):
     @classmethod
     def setUpClass(cls):
+
         cls.host = socket.gethostbyname(socket.gethostname())
         cls.selenium = webdriver.Remote(
             command_executor="http://selenium:4444/wd/hub",
@@ -79,6 +79,25 @@ class AdminConfirmIntegrationTestCase(LiveServerTestCase):
         )
         super().setUpClass()
 
+    def setUp(self):
+        self.superuser = User.objects.create_superuser(
+            username="super", email="super@email.org", password="pass"
+        )
+        self.client.force_login(self.superuser)
+
+        cookie = self.client.cookies["sessionid"]
+        self.selenium.get(
+            self.live_server_url + "/admin/"
+        )  # selenium will set cookie domain based on current page domain
+        self.selenium.add_cookie(
+            {"name": "sessionid", "value": cookie.value, "secure": False, "path": "/"}
+        )
+        return super().setUp()
+
+    def tearDown(self):
+        cache.clear()
+        return super().tearDown()
+
     @classmethod
     def tearDownClass(cls):
         cls.selenium.quit()
diff --git a/admin_confirm/tests/integration/test_smoke.py b/admin_confirm/tests/integration/test_smoke.py
index d28a67d..ebfa441 100644
--- a/admin_confirm/tests/integration/test_smoke.py
+++ b/admin_confirm/tests/integration/test_smoke.py
@@ -3,5 +3,6 @@ from admin_confirm.tests.helpers import AdminConfirmIntegrationTestCase
 
 class SmokeTest(AdminConfirmIntegrationTestCase):
     def test_load_admin(self):
-        self.selenium.get(self.live_server_url+'/admin/')
-        self.assertIn('Django', self.selenium.title)
+        self.selenium.get(self.live_server_url + "/admin/")
+        self.assertIn("Django", self.selenium.title)
+        self.assertIn("Market", self.selenium.page_source)
diff --git a/admin_confirm/tests/integration/test_with_cache.py b/admin_confirm/tests/integration/test_with_cache.py
new file mode 100644
index 0000000..0567310
--- /dev/null
+++ b/admin_confirm/tests/integration/test_with_cache.py
@@ -0,0 +1,213 @@
+"""
+Tests confirmation of add/change
+on ModelAdmin that utilize caches
+"""
+import os
+import pytest
+import pkg_resources
+
+from importlib import reload
+from tests.factories import ShopFactory
+from tests.market.models import GeneralManager, Item, ShoppingMall, Town
+
+from admin_confirm.tests.helpers import AdminConfirmIntegrationTestCase
+from tests.market.admin import shoppingmall_admin
+
+from admin_confirm.constants import CONFIRM_CHANGE
+from selenium.webdriver.support.ui import Select
+from selenium.common.exceptions import NoSuchElementException
+from selenium.webdriver.remote.file_detector import LocalFileDetector
+from django.core.files.uploadedfile import SimpleUploadedFile
+from tempfile import NamedTemporaryFile
+
+
+class ConfirmWithInlinesTests(AdminConfirmIntegrationTestCase):
+    def setUp(self):
+        self.selenium.file_detector = LocalFileDetector()
+        super().setUp()
+
+    def tearDown(self):
+        reload(shoppingmall_admin)
+        super().tearDown()
+
+    def test_models_without_files_should_not_have_confirmation_received(self):
+        mall = ShoppingMall.objects.create(name="mall")
+        self.selenium.get(
+            self.live_server_url + f"/admin/market/shoppingmall/{mall.id}/change/"
+        )
+        # Should ask for confirmation of change
+        self.assertIn(CONFIRM_CHANGE, self.selenium.page_source)
+
+        # Change name
+        name = self.selenium.find_element_by_name("name")
+        name.send_keys("New Name")
+
+        self.selenium.find_element_by_name("_continue").click()
+
+        # Should have hidden form containing the updated name
+        self.assertIn("Confirm", self.selenium.page_source)
+        hidden_form = self.selenium.find_element_by_id("hidden-form")
+        name = hidden_form.find_element_by_name("name")
+        self.assertIn("New Name", name.get_attribute("value"))
+
+        with self.assertRaises(NoSuchElementException):
+            self.selenium.find_element_by_name("_confirmation_received")
+
+        self.selenium.find_element_by_name("_continue").click()
+
+        # Should persist change
+        mall.refresh_from_db()
+        self.assertIn("New Name", mall.name)
+
+    def test_models_with_files_should_have_confirmation_received(self):
+        item = Item.objects.create(name="item", price=1)
+        self.selenium.get(
+            self.live_server_url + f"/admin/market/item/{item.id}/change/"
+        )
+        # Should ask for confirmation of change
+        self.assertIn(CONFIRM_CHANGE, self.selenium.page_source)
+
+        # Change price
+        price = self.selenium.find_element_by_name("price")
+        price.send_keys(2)
+
+        self.selenium.find_element_by_name("_continue").click()
+
+        # Should have hidden form containing the updated price
+        self.assertIn("Confirm", self.selenium.page_source)
+        hidden_form = self.selenium.find_element_by_id("hidden-form")
+        price = hidden_form.find_element_by_name("price")
+        self.assertEqual("21.00", price.get_attribute("value"))
+
+        self.selenium.find_element_by_name("_confirmation_received")
+        self.selenium.find_element_by_name("_continue").click()
+
+        item.refresh_from_db()
+
+    def test_should_save_file_additions(self):
+        selenium_version = pkg_resources.get_distribution("selenium").parsed_version
+        if selenium_version.major < 4:
+            pytest.skip(
+                "Known issue `https://github.com/SeleniumHQ/selenium/issues/8762` with this selenium version."
+            )
+
+        item = Item.objects.create(
+            name="item", price=1, currency=Item.VALID_CURRENCIES[0][0]
+        )
+
+        self.selenium.get(
+            self.live_server_url + f"/admin/market/item/{item.id}/change/"
+        )
+        self.assertIn(CONFIRM_CHANGE, self.selenium.page_source)
+
+        # Make a change to trigger confirmation page
+        price = self.selenium.find_element_by_name("price")
+        price.send_keys(2)
+
+        # Upload a new file
+        self.selenium.find_element_by_id("id_file").send_keys(
+            os.getcwd() + "/screenshot.png"
+        )
+
+        self.selenium.find_element_by_name("_continue").click()
+
+        # Should have hidden form containing the updated price
+        self.assertIn("Confirm", self.selenium.page_source)
+        hidden_form = self.selenium.find_element_by_id("hidden-form")
+        price = hidden_form.find_element_by_name("price")
+        self.assertEqual("21.00", price.get_attribute("value"))
+
+        self.selenium.find_element_by_name("_confirmation_received")
+        self.selenium.find_element_by_name("_continue").click()
+
+        item.refresh_from_db()
+        self.assertEqual(21, int(item.price))
+        self.assertIn("screenshot.png", item.file.name)
+
+    def test_should_save_file_changes(self):
+        selenium_version = pkg_resources.get_distribution("selenium").parsed_version
+        if selenium_version.major < 4:
+            pytest.skip(
+                "Known issue `https://github.com/SeleniumHQ/selenium/issues/8762` with this selenium version."
+            )
+
+        file = SimpleUploadedFile(
+            name="old_file.jpg",
+            content=open("screenshot.png", "rb").read(),
+            content_type="image/jpeg",
+        )
+        item = Item.objects.create(
+            name="item", price=1, currency=Item.VALID_CURRENCIES[0][0], file=file
+        )
+
+        self.selenium.get(
+            self.live_server_url + f"/admin/market/item/{item.id}/change/"
+        )
+        self.assertIn(CONFIRM_CHANGE, self.selenium.page_source)
+
+        # Make a change to trigger confirmation page
+        price = self.selenium.find_element_by_name("price")
+        price.send_keys(2)
+
+        # Upload a new file
+        self.selenium.find_element_by_id("id_file").send_keys(
+            os.getcwd() + "/screenshot.png"
+        )
+
+        self.selenium.find_element_by_name("_continue").click()
+
+        # Should have hidden form containing the updated price
+        self.assertIn("Confirm", self.selenium.page_source)
+        hidden_form = self.selenium.find_element_by_id("hidden-form")
+        price = hidden_form.find_element_by_name("price")
+        self.assertEqual("21.00", price.get_attribute("value"))
+
+        self.selenium.find_element_by_name("_confirmation_received")
+        self.selenium.find_element_by_name("_continue").click()
+
+        item.refresh_from_db()
+        self.assertEqual(21, int(item.price))
+        self.assertIn("screenshot.png", item.file.name)
+
+    def test_should_remove_file_if_clear_selected(self):
+        file = SimpleUploadedFile(
+            name="old_file.jpg",
+            content=open("screenshot.png", "rb").read(),
+            content_type="image/jpeg",
+        )
+        item = Item.objects.create(
+            name="item", price=1, currency=Item.VALID_CURRENCIES[0][0], file=file
+        )
+
+        self.selenium.get(
+            self.live_server_url + f"/admin/market/item/{item.id}/change/"
+        )
+        self.assertIn(CONFIRM_CHANGE, self.selenium.page_source)
+
+        # Make a change to trigger confirmation page
+        price = self.selenium.find_element_by_name("price")
+        price.send_keys(2)
+
+        # Choose to clear the existing file
+        self.selenium.find_element_by_id("file-clear_id").click()
+        self.assertTrue(
+            self.selenium.find_element_by_xpath(
+                ".//*[@id='file-clear_id']"
+            ).get_attribute("checked")
+        )
+
+        self.selenium.find_element_by_name("_continue").click()
+
+        # Should have hidden form containing the updated price
+        self.assertIn("Confirm", self.selenium.page_source)
+        hidden_form = self.selenium.find_element_by_id("hidden-form")
+        price = hidden_form.find_element_by_name("price")
+        self.assertEqual("21.00", price.get_attribute("value"))
+
+        self.selenium.find_element_by_name("_confirmation_received")
+        self.selenium.find_element_by_name("_continue").click()
+
+        item.refresh_from_db()
+        self.assertEqual(21, int(item.price))
+        # Should have cleared `file` since clear was selected
+        self.assertFalse(item.file)
diff --git a/admin_confirm/tests/integration/test_with_inlines.py b/admin_confirm/tests/integration/test_with_inlines.py
new file mode 100644
index 0000000..ae24a2a
--- /dev/null
+++ b/admin_confirm/tests/integration/test_with_inlines.py
@@ -0,0 +1,202 @@
+"""
+Tests confirmation of add/change
+on ModelAdmin that includes inlines
+
+Does not test confirmation of inline changes
+"""
+import pytest
+import pkg_resources
+from importlib import reload
+from tests.factories import ShopFactory
+from tests.market.models import GeneralManager, ShoppingMall, Town
+
+from admin_confirm.tests.helpers import AdminConfirmIntegrationTestCase
+from tests.market.admin import shoppingmall_admin
+
+from admin_confirm.constants import CONFIRM_CHANGE
+from selenium.webdriver.support.ui import Select
+
+
+class ConfirmWithInlinesTests(AdminConfirmIntegrationTestCase):
+    def setUp(self):
+        self.admin = shoppingmall_admin.ShoppingMallAdmin
+        self.admin.inlines = [shoppingmall_admin.ShopInline]
+        super().setUp()
+
+    def tearDown(self):
+        reload(shoppingmall_admin)
+        super().tearDown()
+
+    def test_should_have_hidden_form(self):
+        mall = ShoppingMall.objects.create(name="mall")
+        self.selenium.get(
+            self.live_server_url + f"/admin/market/shoppingmall/{mall.id}/change/"
+        )
+        # Should ask for confirmation of change
+        self.assertIn(CONFIRM_CHANGE, self.selenium.page_source)
+
+        # Change name
+        name = self.selenium.find_element_by_name("name")
+        name.send_keys("New Name")
+
+        self.selenium.find_element_by_name("_continue").click()
+
+        # Should have hidden form containing the updated name
+        self.assertIn("Confirm", self.selenium.page_source)
+        hidden_form = self.selenium.find_element_by_id("hidden-form")
+        name = hidden_form.find_element_by_name("name")
+        self.assertIn("New Name", name.get_attribute("value"))
+
+        self.selenium.find_element_by_name("_continue").click()
+
+        # Should persist change
+        mall.refresh_from_db()
+        self.assertIn("New Name", mall.name)
+
+    def test_should_have_hidden_formsets(self):
+        # Not having formsets would cause a `ManagementForm tampered with` issue
+        gm = GeneralManager.objects.create(name="gm")
+        shops = [ShopFactory(name=i) for i in range(3)]
+        town = Town.objects.create(name="town")
+        mall = ShoppingMall.objects.create(name="mall", general_manager=gm, town=town)
+        mall.shops.set(shops)
+
+        self.selenium.get(
+            self.live_server_url + f"/admin/market/shoppingmall/{mall.id}/change/"
+        )
+        self.assertIn(CONFIRM_CHANGE, self.selenium.page_source)
+
+        # Make a change to trigger confirmation page
+        name = self.selenium.find_element_by_name("name")
+        name.send_keys("New Name")
+
+        self.selenium.find_element_by_name("_continue").click()
+
+        self.assertIn("Confirm", self.selenium.page_source)
+
+        hidden_form = self.selenium.find_element_by_id("hidden-form")
+        hidden_form.find_element_by_name("ShoppingMall_shops-TOTAL_FORMS")
+        self.selenium.find_element_by_name("_continue").click()
+
+        mall.refresh_from_db()
+        self.assertIn("New Name", mall.name)
+
+    def test_should_have_saved_inline_changes(self):
+        gm = GeneralManager.objects.create(name="gm")
+        town = Town.objects.create(name="town")
+        mall = ShoppingMall.objects.create(name="mall", general_manager=gm, town=town)
+
+        shops = [ShopFactory(name=i) for i in range(3)]
+
+        self.selenium.get(
+            self.live_server_url + f"/admin/market/shoppingmall/{mall.id}/change/"
+        )
+        self.assertIn(CONFIRM_CHANGE, self.selenium.page_source)
+
+        # Make a change to trigger confirmation page
+        name = self.selenium.find_element_by_name("name")
+        name.send_keys("New Name")
+
+        # Change shops via inline form
+        select_shop = Select(
+            self.selenium.find_element_by_name("ShoppingMall_shops-0-shop")
+        )
+        select_shop.select_by_value(str(shops[2].id))
+
+        self.selenium.find_element_by_name("_continue").click()
+
+        self.assertIn("Confirm", self.selenium.page_source)
+
+        hidden_form = self.selenium.find_element_by_id("hidden-form")
+        hidden_form.find_element_by_name("ShoppingMall_shops-TOTAL_FORMS")
+        self.selenium.find_element_by_name("_continue").click()
+
+        mall.refresh_from_db()
+        self.assertIn("New Name", mall.name)
+        self.assertIn(shops[2], mall.shops.all())
+
+    def test_should_respect_get_inlines(self):
+        # New in Django 3.0
+        django_version = pkg_resources.get_distribution("Django").parsed_version
+        if django_version.major < 3:
+            pytest.skip(
+                "get_inlines() introducted in Django 3.0, and is not in this version"
+            )
+
+        shoppingmall_admin.ShoppingMallAdmin.inlines = []
+        shoppingmall_admin.ShoppingMallAdmin.get_inlines = (
+            lambda self, request, obj=None: [shoppingmall_admin.ShopInline]
+        )
+
+        gm = GeneralManager.objects.create(name="gm")
+        town = Town.objects.create(name="town")
+        mall = ShoppingMall.objects.create(name="mall", general_manager=gm, town=town)
+
+        shops = [ShopFactory(name=i) for i in range(3)]
+
+        self.selenium.get(
+            self.live_server_url + f"/admin/market/shoppingmall/{mall.id}/change/"
+        )
+        self.assertIn(CONFIRM_CHANGE, self.selenium.page_source)
+
+        # Make a change to trigger confirmation page
+        name = self.selenium.find_element_by_name("name")
+        name.send_keys("New Name")
+
+        # Change shops via inline form
+        select_shop = Select(
+            self.selenium.find_element_by_name("ShoppingMall_shops-0-shop")
+        )
+        select_shop.select_by_value(str(shops[2].id))
+
+        self.selenium.find_element_by_name("_continue").click()
+
+        self.assertIn("Confirm", self.selenium.page_source)
+
+        hidden_form = self.selenium.find_element_by_id("hidden-form")
+        hidden_form.find_element_by_name("ShoppingMall_shops-TOTAL_FORMS")
+        self.selenium.find_element_by_name("_continue").click()
+
+        mall.refresh_from_db()
+        self.assertIn("New Name", mall.name)
+        self.assertIn(shops[2], mall.shops.all())
+
+    def test_should_respect_get_inline_instances(self):
+        shoppingmall_admin.ShoppingMallAdmin.inlines = []
+        shoppingmall_admin.ShoppingMallAdmin.get_inline_instances = (
+            lambda self, request, obj=None: shoppingmall_admin.ShopInline(
+                self.model, self.admin_site
+            )
+        )
+        gm = GeneralManager.objects.create(name="gm")
+        town = Town.objects.create(name="town")
+        mall = ShoppingMall.objects.create(name="mall", general_manager=gm, town=town)
+
+        shops = [ShopFactory(name=i) for i in range(3)]
+
+        self.selenium.get(
+            self.live_server_url + f"/admin/market/shoppingmall/{mall.id}/change/"
+        )
+        self.assertIn(CONFIRM_CHANGE, self.selenium.page_source)
+
+        # Make a change to trigger confirmation page
+        name = self.selenium.find_element_by_name("name")
+        name.send_keys("New Name")
+
+        # Change shops via inline form
+        select_shop = Select(
+            self.selenium.find_element_by_name("ShoppingMall_shops-0-shop")
+        )
+        select_shop.select_by_value(str(shops[2].id))
+
+        self.selenium.find_element_by_name("_continue").click()
+
+        self.assertIn("Confirm", self.selenium.page_source)
+
+        hidden_form = self.selenium.find_element_by_id("hidden-form")
+        hidden_form.find_element_by_name("ShoppingMall_shops-TOTAL_FORMS")
+        self.selenium.find_element_by_name("_continue").click()
+
+        mall.refresh_from_db()
+        self.assertIn("New Name", mall.name)
+        self.assertIn(shops[2], mall.shops.all())
diff --git a/admin_confirm/tests/unit/test_admin_options.py b/admin_confirm/tests/unit/test_admin_options.py
index 0f91a29..58c5e5d 100644
--- a/admin_confirm/tests/unit/test_admin_options.py
+++ b/admin_confirm/tests/unit/test_admin_options.py
@@ -21,8 +21,6 @@ class TestAdminOptions(AdminConfirmTestCase):
         mall.shops.set(shops)
 
         # new values
-        gm2 = GeneralManager.objects.create(name="gm2")
-        shops2 = [ShopFactory() for i in range(3)]
         town2 = Town.objects.create(name="town2")
 
         data = {
@@ -92,7 +90,6 @@ class TestAdminOptions(AdminConfirmTestCase):
 
         # new values
         gm2 = GeneralManager.objects.create(name="gm2")
-        shops2 = [ShopFactory() for i in range(3)]
         town2 = Town.objects.create(name="town2")
 
         data = {
@@ -164,7 +161,6 @@ class TestAdminOptions(AdminConfirmTestCase):
 
         # new values
         gm2 = GeneralManager.objects.create(name="gm2")
-        shops2 = [ShopFactory() for i in range(3)]
         town2 = Town.objects.create(name="town2")
 
         data = {
@@ -205,7 +201,6 @@ class TestAdminOptions(AdminConfirmTestCase):
 
         # new values
         gm2 = GeneralManager.objects.create(name="gm2")
-        shops2 = [ShopFactory() for i in range(3)]
         town2 = Town.objects.create(name="town2")
 
         data = {
@@ -246,7 +241,6 @@ class TestAdminOptions(AdminConfirmTestCase):
 
         # new values
         gm2 = GeneralManager.objects.create(name="gm2")
-        shops2 = [ShopFactory() for i in range(3)]
         town2 = Town.objects.create(name="town2")
 
         data = {
diff --git a/admin_confirm/tests/unit/test_confirm_change_and_add_m2m_field.py b/admin_confirm/tests/unit/test_confirm_change_and_add_m2m_field.py
index e564c94..6344454 100644
--- a/admin_confirm/tests/unit/test_confirm_change_and_add_m2m_field.py
+++ b/admin_confirm/tests/unit/test_confirm_change_and_add_m2m_field.py
@@ -1,5 +1,4 @@
 from unittest import mock
-from admin_confirm.admin import AdminConfirmMixin
 from django.urls import reverse
 
 from admin_confirm.tests.helpers import AdminConfirmTestCase
diff --git a/admin_confirm/tests/unit/test_file_cache.py b/admin_confirm/tests/unit/test_file_cache.py
index 1418c9d..adf59d6 100644
--- a/admin_confirm/tests/unit/test_file_cache.py
+++ b/admin_confirm/tests/unit/test_file_cache.py
@@ -170,7 +170,7 @@ class TestFileCache(AdminConfirmTestCase):
             self.assertNotIn("You may edit it again below.", message)
 
         # Should have redirected to changelist
-        self.assertEqual(response.url, f"/admin/market/item/")
+        self.assertEqual(response.url, "/admin/market/item/")
 
         # Should not have changed existing item
         item.refresh_from_db()
@@ -290,7 +290,7 @@ class TestFileCache(AdminConfirmTestCase):
         data[CONFIRMATION_RECEIVED] = True
 
         with mock.patch.object(ItemAdmin, "message_user") as message_user:
-            response = self.client.post(f"/admin/market/item/add/", data=data)
+            response = self.client.post("/admin/market/item/add/", data=data)
             # Should show message to user with correct obj and path
             message_user.assert_called_once()
             message = message_user.call_args[0][1]
@@ -299,7 +299,7 @@ class TestFileCache(AdminConfirmTestCase):
             self.assertNotIn("You may edit it again below.", message)
 
         # Should not have redirected to changelist
-        self.assertEqual(response.url, f"/admin/market/item/")
+        self.assertEqual(response.url, "/admin/market/item/")
 
         # Should not have changed existing item
         self.item.refresh_from_db()
@@ -353,7 +353,7 @@ class TestFileCache(AdminConfirmTestCase):
         data[CONFIRMATION_RECEIVED] = True
 
         with mock.patch.object(ItemAdmin, "message_user") as message_user:
-            response = self.client.post(f"/admin/market/item/add/", data=data)
+            response = self.client.post("/admin/market/item/add/", data=data)
             # Should show message to user with correct obj and path
             message_user.assert_called_once()
             message = message_user.call_args[0][1]
@@ -362,7 +362,7 @@ class TestFileCache(AdminConfirmTestCase):
             self.assertNotIn("You may edit it again below.", message)
 
         # Should not have redirected to changelist
-        self.assertEqual(response.url, f"/admin/market/item/")
+        self.assertEqual(response.url, "/admin/market/item/")
 
         # Should not have changed existing item
         self.item.refresh_from_db()
@@ -398,17 +398,6 @@ class TestFileCache(AdminConfirmTestCase):
             "_save": True,
         }
 
-        # Upload new file
-        f2 = SimpleUploadedFile(
-            name="test_file2.jpg",
-            content=open(self.image_path, "rb").read(),
-            content_type="image/jpeg",
-        )
-        # Set cache
-        cache_item = Item(
-            name=data["name"], price=data["price"], currency=data["currency"], file=f2
-        )
-
         # Make sure there's no post cached obj
         cache.delete(CACHE_KEYS["object"])
         cache.set(CACHE_KEYS["post"], data)
@@ -418,7 +407,7 @@ class TestFileCache(AdminConfirmTestCase):
         data[CONFIRMATION_RECEIVED] = True
 
         with mock.patch.object(ItemAdmin, "message_user") as message_user:
-            response = self.client.post(f"/admin/market/item/add/", data=data)
+            response = self.client.post("/admin/market/item/add/", data=data)
             # Should show message to user with correct obj and path
             message_user.assert_called_once()
             message = message_user.call_args[0][1]
@@ -427,7 +416,7 @@ class TestFileCache(AdminConfirmTestCase):
             self.assertNotIn("You may edit it again below.", message)
 
         # Should not have redirected to changelist
-        self.assertEqual(response.url, f"/admin/market/item/")
+        self.assertEqual(response.url, "/admin/market/item/")
 
         # Should not have changed existing item
         self.item.refresh_from_db()
@@ -463,17 +452,6 @@ class TestFileCache(AdminConfirmTestCase):
             "_save": True,
         }
 
-        # Upload new file
-        f2 = SimpleUploadedFile(
-            name="test_file2.jpg",
-            content=open(self.image_path, "rb").read(),
-            content_type="image/jpeg",
-        )
-        # Set cache
-        cache_item = Item(
-            name=data["name"], price=data["price"], currency=data["currency"], file=f2
-        )
-
         # Make sure there's no cache
         cache.delete(CACHE_KEYS["object"])
         cache.delete(CACHE_KEYS["post"])
@@ -483,7 +461,7 @@ class TestFileCache(AdminConfirmTestCase):
         data[CONFIRMATION_RECEIVED] = True
 
         with mock.patch.object(ItemAdmin, "message_user") as message_user:
-            response = self.client.post(f"/admin/market/item/add/", data=data)
+            response = self.client.post("/admin/market/item/add/", data=data)
             # Should show message to user with correct obj and path
             message_user.assert_called_once()
             message = message_user.call_args[0][1]
@@ -492,7 +470,7 @@ class TestFileCache(AdminConfirmTestCase):
             self.assertNotIn("You may edit it again below.", message)
 
         # Should not have redirected to changelist
-        self.assertEqual(response.url, f"/admin/market/item/")
+        self.assertEqual(response.url, "/admin/market/item/")
 
         # Should not have changed existing item
         self.item.refresh_from_db()
@@ -571,7 +549,7 @@ class TestFileCache(AdminConfirmTestCase):
             self.assertNotIn("You may edit it again below.", message)
 
         # Should have redirected to changelist
-        self.assertEqual(response.url, f"/admin/market/item/")
+        self.assertEqual(response.url, "/admin/market/item/")
 
         # Should not have changed existing item
         item.refresh_from_db()
@@ -601,12 +579,6 @@ class TestFileCache(AdminConfirmTestCase):
         # Load the Change Item Page
         ItemAdmin.save_as_continue = False
 
-        # Upload new image and remove file
-        i2 = SimpleUploadedFile(
-            name="test_image2.jpg",
-            content=open(self.image_path, "rb").read(),
-            content_type="image/jpeg",
-        )
         # Request.POST
         data = {
             "id": item.id,
@@ -619,14 +591,6 @@ class TestFileCache(AdminConfirmTestCase):
             "_saveasnew": True,
         }
 
-        # Set cache
-        cache_item = Item(
-            name=data["name"],
-            price=data["price"],
-            currency=data["currency"],
-            image=i2,
-        )
-
         # Ensure no cached obj
         cache.delete(CACHE_KEYS["object"])
         cache.set(CACHE_KEYS["post"], data)
@@ -647,7 +611,7 @@ class TestFileCache(AdminConfirmTestCase):
             self.assertNotIn("You may edit it again below.", message)
 
         # Should have redirected to changelist
-        self.assertEqual(response.url, f"/admin/market/item/")
+        self.assertEqual(response.url, "/admin/market/item/")
 
         # Should not have changed existing item
         item.refresh_from_db()
@@ -676,12 +640,6 @@ class TestFileCache(AdminConfirmTestCase):
         # Load the Change Item Page
         ItemAdmin.save_as_continue = False
 
-        # Upload new image and remove file
-        i2 = SimpleUploadedFile(
-            name="test_image2.jpg",
-            content=open(self.image_path, "rb").read(),
-            content_type="image/jpeg",
-        )
         # Request.POST
         data = {
             "id": item.id,
@@ -694,14 +652,6 @@ class TestFileCache(AdminConfirmTestCase):
             "_saveasnew": True,
         }
 
-        # Set cache
-        cache_item = Item(
-            name=data["name"],
-            price=data["price"],
-            currency=data["currency"],
-            image=i2,
-        )
-
         # Ensure no cache
         cache.delete(CACHE_KEYS["object"])
         cache.delete(CACHE_KEYS["post"])
@@ -722,7 +672,7 @@ class TestFileCache(AdminConfirmTestCase):
             self.assertNotIn("You may edit it again below.", message)
 
         # Should have redirected to changelist
-        self.assertEqual(response.url, f"/admin/market/item/")
+        self.assertEqual(response.url, "/admin/market/item/")
 
         # Should not have changed existing item
         item.refresh_from_db()
@@ -790,7 +740,7 @@ class TestFileCache(AdminConfirmTestCase):
             self.assertNotIn("You may edit it again below.", message)
 
         # Should have redirected to changelist
-        self.assertEqual(response.url, f"/admin/market/item/")
+        self.assertEqual(response.url, "/admin/market/item/")
 
         # Should have changed existing item
         self.assertEqual(Item.objects.count(), 1)
@@ -890,12 +840,6 @@ class TestFileCache(AdminConfirmTestCase):
         # Load the Change Item Page
         ItemAdmin.save_as_continue = False
 
-        # Upload new image and remove file
-        i2 = SimpleUploadedFile(
-            name="test_image2.jpg",
-            content=open(self.image_path, "rb").read(),
-            content_type="image/jpeg",
-        )
         # Request.POST
         data = {
             "id": item.id,
@@ -930,7 +874,7 @@ class TestFileCache(AdminConfirmTestCase):
             self.assertNotIn("You may edit it again below.", message)
 
         # Should have redirected to changelist
-        self.assertEqual(response.url, f"/admin/market/item/")
+        self.assertEqual(response.url, "/admin/market/item/")
 
         # Should have changed existing item
         self.assertEqual(Item.objects.count(), 1)
diff --git a/docker-compose.yml b/docker-compose.yml
index 5ea487e..f28f953 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -2,7 +2,13 @@ version: "3.9"
 
 services:
   web:
-    build: .
+    build:
+      context: .
+      dockerfile: Dockerfile
+      args:
+        PYTHON_VERSION: "$PYTHON_VERSION"
+        DJANGO_VERSION: "$DJANGO_VERSION"
+        SELENIUM_VERSION: "$SELENIUM_VERSION"
     command: python tests/manage.py runserver 0.0.0.0:8000
     volumes:
       - .:/code
@@ -16,3 +22,5 @@ services:
     ports:
       - "4444:4444"   # Selenium
       - "5900:5900"   # VNC
+    volumes:
+      - .:/code
diff --git a/pytest.ini b/pytest.ini
deleted file mode 100644
index 64cd31d..0000000
--- a/pytest.ini
+++ /dev/null
@@ -1,4 +0,0 @@
-[pytest]
-DJANGO_SETTINGS_MODULE=tests.test_project.settings.test
-addopts = --doctest-modules -ra -l --tb=short --show-capture=stdout --color=yes
-testpaths = admin_confirm
diff --git a/requirements.txt b/requirements.txt
index e056a77..9cc4d8f 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,6 +1,5 @@
 Django>=1.7.0
 factory-boy~=3.0.1
-django-admin-confirm~=0.2.2
 coverage~=5.4
 pytest~=6.2.2
 pytest-django~=4.1.0
@@ -8,4 +7,10 @@ readme-renderer~=28.0
 twine~=3.3.0
 coveralls~=3.0.0
 Pillow~=8.1.0 # For ImageField
-selenium~=3.141.0
+
+# Known issue: https://github.com/SeleniumHQ/selenium/issues/8762
+# Python 3.6 should use because selenium 4 doesn't work with py3.6
+# selenium~=3.141.0
+
+# Others should use
+selenium~=4.0.0.a5
diff --git a/setup.cfg b/setup.cfg
new file mode 100644
index 0000000..aed3ba5
--- /dev/null
+++ b/setup.cfg
@@ -0,0 +1,26 @@
+[flake8]
+max-complexity = 10
+max-line-length = 127
+paths = admin_confirm
+exclude =
+    admin_confirm/tests/*
+    tests/*
+ignore = 
+    C812 # missing trailing comma
+    I001 # isort found an import in the wrong position
+    I004 # sisort found an unexpected blank line in imports
+    Q000 # Remove bad quotes
+    WPS110 # Seems to require no one word variable names
+    WPS305 # Found f string
+    WPS336 # Explicit string concatination
+per-file-ignores =
+    admin_confirm/tests/*: D102, WPS118, WPS204
+[coverage:run]
+relative_files = True
+omit = admin_confirm/tests/*
+branch = True
+
+[tool:pytest]
+DJANGO_SETTINGS_MODULE=tests.test_project.settings.test
+addopts = --doctest-modules -ra -l --tb=short --show-capture=stdout --color=yes
+testpaths = admin_confirm
diff --git a/setup.py b/setup.py
index e2fc88a..3bfc8c1 100644
--- a/setup.py
+++ b/setup.py
@@ -1,4 +1,5 @@
 import os
+
 from setuptools import setup
 
 here = os.path.abspath(os.path.dirname(__file__))
@@ -8,7 +9,7 @@ setup(
     name="django-admin-confirm",
     version="0.2.3.dev9",
     packages=["admin_confirm"],
-    description="Adds confirmation to Django Admin changes, additions and actions",
+    description=("Adds confirmation to Django Admin changes, additions and actions"),
     long_description_content_type="text/markdown",
     long_description=README,
     author="Thu Trang Pham",
diff --git a/tests/market/migrations/0004_inventory_notes.py b/tests/market/migrations/0004_inventory_notes.py
index ab483c2..d314bda 100644
--- a/tests/market/migrations/0004_inventory_notes.py
+++ b/tests/market/migrations/0004_inventory_notes.py
@@ -6,13 +6,15 @@ from django.db import migrations, models
 class Migration(migrations.Migration):
 
     dependencies = [
-        ('market', '0003_auto_20201108_1717'),
+        ("market", "0003_auto_20201108_1717"),
     ]
 
     operations = [
         migrations.AddField(
-            model_name='inventory',
-            name='notes',
-            field=models.TextField(blank=True, default='This is the default', null=True),
+            model_name="inventory",
+            name="notes",
+            field=models.TextField(
+                blank=True, default="This is the default", null=True
+            ),
         ),
     ]
diff --git a/tests/market/migrations/0005_shoppingmall.py b/tests/market/migrations/0005_shoppingmall.py
index 8ec600e..d367a59 100644
--- a/tests/market/migrations/0005_shoppingmall.py
+++ b/tests/market/migrations/0005_shoppingmall.py
@@ -6,16 +6,24 @@ from django.db import migrations, models
 class Migration(migrations.Migration):
 
     dependencies = [
-        ('market', '0004_inventory_notes'),
+        ("market", "0004_inventory_notes"),
     ]
 
     operations = [
         migrations.CreateModel(
-            name='ShoppingMall',
+            name="ShoppingMall",
             fields=[
-                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
-                ('name', models.CharField(max_length=120)),
-                ('shops', models.ManyToManyField(to='market.Shop')),
+                (
+                    "id",
+                    models.AutoField(
+                        auto_created=True,
+                        primary_key=True,
+                        serialize=False,
+                        verbose_name="ID",
+                    ),
+                ),
+                ("name", models.CharField(max_length=120)),
+                ("shops", models.ManyToManyField(to="market.Shop")),
             ],
         ),
     ]
diff --git a/tests/market/migrations/0006_auto_20210222_0312.py b/tests/market/migrations/0006_auto_20210222_0312.py
index 484de32..103ac21 100644
--- a/tests/market/migrations/0006_auto_20210222_0312.py
+++ b/tests/market/migrations/0006_auto_20210222_0312.py
@@ -7,42 +7,68 @@ import django.db.models.deletion
 class Migration(migrations.Migration):
 
     dependencies = [
-        ('market', '0005_shoppingmall'),
+        ("market", "0005_shoppingmall"),
     ]
 
     operations = [
         migrations.CreateModel(
-            name='GeneralManager',
+            name="GeneralManager",
             fields=[
-                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
-                ('name', models.CharField(max_length=120)),
+                (
+                    "id",
+                    models.AutoField(
+                        auto_created=True,
+                        primary_key=True,
+                        serialize=False,
+                        verbose_name="ID",
+                    ),
+                ),
+                ("name", models.CharField(max_length=120)),
             ],
         ),
         migrations.CreateModel(
-            name='Town',
+            name="Town",
             fields=[
-                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
-                ('name', models.CharField(max_length=120)),
+                (
+                    "id",
+                    models.AutoField(
+                        auto_created=True,
+                        primary_key=True,
+                        serialize=False,
+                        verbose_name="ID",
+                    ),
+                ),
+                ("name", models.CharField(max_length=120)),
             ],
         ),
         migrations.AddField(
-            model_name='item',
-            name='file',
-            field=models.FileField(blank=True, null=True, upload_to='tmp/files'),
+            model_name="item",
+            name="file",
+            field=models.FileField(blank=True, null=True, upload_to="tmp/files"),
         ),
         migrations.AddField(
-            model_name='item',
-            name='image',
-            field=models.ImageField(blank=True, null=True, upload_to='tmp/items'),
+            model_name="item",
+            name="image",
+            field=models.ImageField(blank=True, null=True, upload_to="tmp/items"),
         ),
         migrations.AddField(
-            model_name='shoppingmall',
-            name='general_manager',
-            field=models.OneToOneField(blank=True, null=True, on_delete=django.db.models.deletion.CASCADE, to='market.generalmanager'),
+            model_name="shoppingmall",
+            name="general_manager",
+            field=models.OneToOneField(
+                blank=True,
+                null=True,
+                on_delete=django.db.models.deletion.CASCADE,
+                to="market.generalmanager",
+            ),
         ),
         migrations.AddField(
-            model_name='shoppingmall',
-            name='town',
-            field=models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.CASCADE, to='market.town'),
+            model_name="shoppingmall",
+            name="town",
+            field=models.ForeignKey(
+                blank=True,
+                null=True,
+                on_delete=django.db.models.deletion.CASCADE,
+                to="market.town",
+            ),
         ),
     ]
diff --git a/tests/market/migrations/0007_generalmanager_headshot.py b/tests/market/migrations/0007_generalmanager_headshot.py
index 645e815..574c287 100644
--- a/tests/market/migrations/0007_generalmanager_headshot.py
+++ b/tests/market/migrations/0007_generalmanager_headshot.py
@@ -6,13 +6,15 @@ from django.db import migrations, models
 class Migration(migrations.Migration):
 
     dependencies = [
-        ('market', '0006_auto_20210222_0312'),
+        ("market", "0006_auto_20210222_0312"),
     ]
 
     operations = [
         migrations.AddField(
-            model_name='generalmanager',
-            name='headshot',
-            field=models.ImageField(blank=True, null=True, upload_to='tmp/gm/headshots'),
+            model_name="generalmanager",
+            name="headshot",
+            field=models.ImageField(
+                blank=True, null=True, upload_to="tmp/gm/headshots"
+            ),
         ),
     ]
diff --git a/tests/market/migrations/0008_item_description.py b/tests/market/migrations/0008_item_description.py
index 8915db6..ea78c5c 100644
--- a/tests/market/migrations/0008_item_description.py
+++ b/tests/market/migrations/0008_item_description.py
@@ -6,13 +6,13 @@ from django.db import migrations, models
 class Migration(migrations.Migration):
 
     dependencies = [
-        ('market', '0007_generalmanager_headshot'),
+        ("market", "0007_generalmanager_headshot"),
     ]
 
     operations = [
         migrations.AddField(
-            model_name='item',
-            name='description',
+            model_name="item",
+            name="description",
             field=models.TextField(blank=True, null=True),
         ),
     ]
diff --git a/tests/market/migrations/0009_auto_20210304_0355.py b/tests/market/migrations/0009_auto_20210304_0355.py
new file mode 100644
index 0000000..9a73496
--- /dev/null
+++ b/tests/market/migrations/0009_auto_20210304_0355.py
@@ -0,0 +1,18 @@
+# Generated by Django 3.1.7 on 2021-03-04 03:55
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("market", "0008_item_description"),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name="shoppingmall",
+            name="shops",
+            field=models.ManyToManyField(blank=True, null=True, to="market.Shop"),
+        ),
+    ]
diff --git a/tests/market/models.py b/tests/market/models.py
index 9658aec..b4f1d04 100644
--- a/tests/market/models.py
+++ b/tests/market/models.py
@@ -49,7 +49,7 @@ class Town(models.Model):
 
 class ShoppingMall(models.Model):
     name = models.CharField(max_length=120)
-    shops = models.ManyToManyField(Shop)
+    shops = models.ManyToManyField(Shop, blank=True, null=True)
     general_manager = models.OneToOneField(
         GeneralManager, on_delete=models.CASCADE, null=True, blank=True
     )
diff --git a/tests/test_project/settings/base.py b/tests/test_project/settings/base.py
index 27009f9..682a8c8 100644
--- a/tests/test_project/settings/base.py
+++ b/tests/test_project/settings/base.py
@@ -24,13 +24,13 @@ SECRET_KEY = "=yddl-40388w3e2hl$e8)revce=n67_idi8pfejtn3!+2%!_qt"
 # SECURITY WARNING: don't run with debug turned on in production!
 DEBUG = True
 
-USE_DCOKER = os.environ.get("USE_DOCKER", '').lower() == "true"
+USE_DCOKER = os.environ.get("USE_DOCKER", "").lower() == "true"
 
 ALLOWED_HOSTS = ["127.0.0.1", "localhost"]
 if USE_DCOKER:
     import socket
 
-    ALLOWED_HOSTS = [socket.gethostbyname(socket.gethostname())]
+    ALLOWED_HOSTS += [socket.gethostbyname(socket.gethostname())]
 
 # Application definition
 
diff --git a/tests/test_project/settings/local.py b/tests/test_project/settings/local.py
index 80a24fc..178e709 100644
--- a/tests/test_project/settings/local.py
+++ b/tests/test_project/settings/local.py
@@ -1,5 +1,5 @@
 from .base import *
 
-INSTALLED_APPS = INSTALLED_APPS + ['market']
+INSTALLED_APPS = INSTALLED_APPS + ["market"]
 WSGI_APPLICATION = "test_project.wsgi.application"
 ROOT_URLCONF = "test_project.urls"
diff --git a/tests/test_project/settings/test.py b/tests/test_project/settings/test.py
index 2e221c3..8518949 100644
--- a/tests/test_project/settings/test.py
+++ b/tests/test_project/settings/test.py
@@ -1,5 +1,5 @@
 from .base import *
 
-INSTALLED_APPS = INSTALLED_APPS + ['tests.market']
+INSTALLED_APPS = INSTALLED_APPS + ["tests.market"]
 WSGI_APPLICATION = "tests.test_project.wsgi.application"
 ROOT_URLCONF = "tests.test_project.urls"