diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index cd2366d560..b9ef3dd693 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -9,7 +9,7 @@ repos:
     hooks:
       - id: isort
   - repo: https://github.com/PyCQA/flake8
-    rev: 4.0.1
+    rev: 5.0.0
     hooks:
       - id: flake8
   - repo: https://github.com/pre-commit/mirrors-eslint
diff --git a/django/contrib/contenttypes/management/commands/remove_stale_contenttypes.py b/django/contrib/contenttypes/management/commands/remove_stale_contenttypes.py
index 3002ceaf53..eccd3aa2c9 100644
--- a/django/contrib/contenttypes/management/commands/remove_stale_contenttypes.py
+++ b/django/contrib/contenttypes/management/commands/remove_stale_contenttypes.py
@@ -72,18 +72,18 @@ class Command(BaseCommand):
                                 )
                     content_type_display = "\n".join(ct_info)
                     self.stdout.write(
-                        """Some content types in your database are stale and can be deleted.
-Any objects that depend on these content types will also be deleted.
-The content types and dependent objects that would be deleted are:
-
-%s
-
-This list doesn't include any cascade deletions to data outside of Django's
-models (uncommon).
-
-Are you sure you want to delete these content types?
-If you're unsure, answer 'no'."""
-                        % content_type_display
+                        "Some content types in your database are stale and can be "
+                        "deleted.\n"
+                        "Any objects that depend on these content types will also be "
+                        "deleted.\n"
+                        "The content types and dependent objects that would be deleted "
+                        "are:\n\n"
+                        f"{content_type_display}\n\n"
+                        "This list doesn't include any cascade deletions to data "
+                        "outside of Django's\n"
+                        "models (uncommon).\n\n"
+                        "Are you sure you want to delete these content types?\n"
+                        "If you're unsure, answer 'no'."
                     )
                     ok_to_delete = input("Type 'yes' to continue, or 'no' to cancel: ")
                 else:
diff --git a/tests/admin_views/tests.py b/tests/admin_views/tests.py
index 11b8aff346..88468e883c 100644
--- a/tests/admin_views/tests.py
+++ b/tests/admin_views/tests.py
@@ -803,8 +803,9 @@ class AdminViewBasicTest(AdminViewBasicTestCase):
         self.assertIs(response.context["cl"].has_related_field_in_list_display(), False)
 
     def test_limited_filter(self):
-        """Ensure admin changelist filters do not contain objects excluded via limit_choices_to.
-        This also tests relation-spanning filters (e.g. 'color__value').
+        """
+        Admin changelist filters do not contain objects excluded via
+        limit_choices_to.
         """
         response = self.client.get(reverse("admin:admin_views_thing_changelist"))
         self.assertContains(
diff --git a/tests/forms_tests/tests/test_forms.py b/tests/forms_tests/tests/test_forms.py
index ec911ee961..6005472194 100644
--- a/tests/forms_tests/tests/test_forms.py
+++ b/tests/forms_tests/tests/test_forms.py
@@ -130,9 +130,12 @@ class FormsTestCase(SimpleTestCase):
 
         self.assertHTMLEqual(
             "\n".join(form_output),
-            """<input type="text" name="first_name" value="John" id="id_first_name" required>
-<input type="text" name="last_name" value="Lennon" id="id_last_name" required>
-<input type="text" name="birthday" value="1940-10-9" id="id_birthday" required>""",
+            '<input type="text" name="first_name" value="John" id="id_first_name" '
+            "required>"
+            '<input type="text" name="last_name" value="Lennon" id="id_last_name" '
+            "required>"
+            '<input type="text" name="birthday" value="1940-10-9" id="id_birthday" '
+            "required>",
         )
 
         form_output = []
@@ -893,10 +896,12 @@ class FormsTestCase(SimpleTestCase):
         f = BeatleForm(auto_id=False)
         self.assertHTMLEqual(
             "\n".join(str(bf) for bf in f["name"]),
-            """<label><input type="radio" name="name" value="john" required> John</label>
-<label><input type="radio" name="name" value="paul" required> Paul</label>
-<label><input type="radio" name="name" value="george" required> George</label>
-<label><input type="radio" name="name" value="ringo" required> Ringo</label>""",
+            '<label><input type="radio" name="name" value="john" required> John</label>'
+            '<label><input type="radio" name="name" value="paul" required> Paul</label>'
+            '<label><input type="radio" name="name" value="george" required> George'
+            "</label>"
+            '<label><input type="radio" name="name" value="ringo" required> Ringo'
+            "</label>",
         )
         self.assertHTMLEqual(
             "\n".join("<div>%s</div>" % bf for bf in f["name"]),
@@ -2229,8 +2234,10 @@ class FormsTestCase(SimpleTestCase):
         p = UserRegistration(auto_id=False)
         self.assertHTMLEqual(
             p.as_ul(),
-            """<li>Username: <input type="text" name="username" maxlength="10" required></li>
-<li>Password: <input type="password" name="password" maxlength="10" required></li>""",
+            '<li>Username: <input type="text" name="username" maxlength="10" required>'
+            "</li>"
+            '<li>Password: <input type="password" name="password" maxlength="10" '
+            "required></li>",
         )
 
     def test_specifying_labels(self):
@@ -2320,8 +2327,9 @@ class FormsTestCase(SimpleTestCase):
         p = UserRegistration(auto_id=False)
         self.assertHTMLEqual(
             p.as_ul(),
-            """<li>Username: <input type="text" name="username" maxlength="10" required></li>
-<li>Password: <input type="password" name="password" required></li>""",
+            '<li>Username: <input type="text" name="username" maxlength="10" required>'
+            "</li>"
+            '<li>Password: <input type="password" name="password" required></li>',
         )
         p = UserRegistration(auto_id="id_%s")
         self.assertHTMLEqual(
@@ -2945,11 +2953,12 @@ Options: <select multiple name="options" required>
         p = UserRegistration({"username": "foo"}, auto_id=False)
         self.assertHTMLEqual(
             p.as_ul(),
-            """<li>Username: <input type="text" name="username" value="foo" maxlength="10" required>
-<span class="helptext">e.g., user@example.com</span></li>
-<li><ul class="errorlist"><li>This field is required.</li></ul>
-Password: <input type="password" name="password" required>
-<span class="helptext">Wählen Sie mit Bedacht.</span></li>""",
+            '<li>Username: <input type="text" name="username" value="foo" '
+            'maxlength="10" required>'
+            '<span class="helptext">e.g., user@example.com</span></li>'
+            '<li><ul class="errorlist"><li>This field is required.</li></ul>'
+            'Password: <input type="password" name="password" required>'
+            '<span class="helptext">Wählen Sie mit Bedacht.</span></li>',
         )
 
         # help_text is not displayed for hidden fields. It can be used for documentation
diff --git a/tests/forms_tests/tests/test_formsets.py b/tests/forms_tests/tests/test_formsets.py
index d159409afa..96a2189d70 100644
--- a/tests/forms_tests/tests/test_formsets.py
+++ b/tests/forms_tests/tests/test_formsets.py
@@ -245,10 +245,11 @@ class FormsFormsetTestCase(SimpleTestCase):
         )
         self.assertHTMLEqual(
             "\n".join(form.as_ul() for form in formset.forms),
-            """<li>Choice: <input type="text" name="choices-0-choice" value="Calexico"></li>
-<li>Votes: <input type="number" name="choices-0-votes" value="100"></li>
-<li>Choice: <input type="text" name="choices-1-choice"></li>
-<li>Votes: <input type="number" name="choices-1-votes"></li>""",
+            '<li>Choice: <input type="text" name="choices-0-choice" value="Calexico">'
+            "</li>"
+            '<li>Votes: <input type="number" name="choices-0-votes" value="100"></li>'
+            '<li>Choice: <input type="text" name="choices-1-choice"></li>'
+            '<li>Votes: <input type="number" name="choices-1-votes"></li>',
         )
 
     def test_blank_form_unfilled(self):
@@ -564,14 +565,15 @@ class FormsFormsetTestCase(SimpleTestCase):
         formset = ChoiceFormSet(initial=initial, auto_id=False, prefix="choices")
         self.assertHTMLEqual(
             "\n".join(form.as_ul() for form in formset.forms),
-            """<li>Choice: <input type="text" name="choices-0-choice" value="Calexico"></li>
-<li>Votes: <input type="number" name="choices-0-votes" value="100"></li>
-<li>Choice: <input type="text" name="choices-1-choice"></li>
-<li>Votes: <input type="number" name="choices-1-votes"></li>
-<li>Choice: <input type="text" name="choices-2-choice"></li>
-<li>Votes: <input type="number" name="choices-2-votes"></li>
-<li>Choice: <input type="text" name="choices-3-choice"></li>
-<li>Votes: <input type="number" name="choices-3-votes"></li>""",
+            '<li>Choice: <input type="text" name="choices-0-choice" value="Calexico">'
+            "</li>"
+            '<li>Votes: <input type="number" name="choices-0-votes" value="100"></li>'
+            '<li>Choice: <input type="text" name="choices-1-choice"></li>'
+            '<li>Votes: <input type="number" name="choices-1-votes"></li>'
+            '<li>Choice: <input type="text" name="choices-2-choice"></li>'
+            '<li>Votes: <input type="number" name="choices-2-votes"></li>'
+            '<li>Choice: <input type="text" name="choices-3-choice"></li>'
+            '<li>Votes: <input type="number" name="choices-3-votes"></li>',
         )
         # Retrieving an empty form works. Tt shows up in the form list.
         self.assertTrue(formset.empty_form.empty_permitted)
@@ -595,15 +597,17 @@ class FormsFormsetTestCase(SimpleTestCase):
         formset = ChoiceFormSet(initial=initial, auto_id=False, prefix="choices")
         self.assertHTMLEqual(
             "\n".join(form.as_ul() for form in formset.forms),
-            """<li>Choice: <input type="text" name="choices-0-choice" value="Calexico"></li>
-<li>Votes: <input type="number" name="choices-0-votes" value="100"></li>
-<li>Delete: <input type="checkbox" name="choices-0-DELETE"></li>
-<li>Choice: <input type="text" name="choices-1-choice" value="Fergie"></li>
-<li>Votes: <input type="number" name="choices-1-votes" value="900"></li>
-<li>Delete: <input type="checkbox" name="choices-1-DELETE"></li>
-<li>Choice: <input type="text" name="choices-2-choice"></li>
-<li>Votes: <input type="number" name="choices-2-votes"></li>
-<li>Delete: <input type="checkbox" name="choices-2-DELETE"></li>""",
+            '<li>Choice: <input type="text" name="choices-0-choice" value="Calexico">'
+            "</li>"
+            '<li>Votes: <input type="number" name="choices-0-votes" value="100"></li>'
+            '<li>Delete: <input type="checkbox" name="choices-0-DELETE"></li>'
+            '<li>Choice: <input type="text" name="choices-1-choice" value="Fergie">'
+            "</li>"
+            '<li>Votes: <input type="number" name="choices-1-votes" value="900"></li>'
+            '<li>Delete: <input type="checkbox" name="choices-1-DELETE"></li>'
+            '<li>Choice: <input type="text" name="choices-2-choice"></li>'
+            '<li>Votes: <input type="number" name="choices-2-votes"></li>'
+            '<li>Delete: <input type="checkbox" name="choices-2-DELETE"></li>',
         )
         # To delete something, set that form's special delete field to 'on'.
         # Let's go ahead and delete Fergie.
@@ -738,15 +742,17 @@ class FormsFormsetTestCase(SimpleTestCase):
         formset = ChoiceFormSet(initial=initial, auto_id=False, prefix="choices")
         self.assertHTMLEqual(
             "\n".join(form.as_ul() for form in formset.forms),
-            """<li>Choice: <input type="text" name="choices-0-choice" value="Calexico"></li>
-<li>Votes: <input type="number" name="choices-0-votes" value="100"></li>
-<li>Order: <input type="number" name="choices-0-ORDER" value="1"></li>
-<li>Choice: <input type="text" name="choices-1-choice" value="Fergie"></li>
-<li>Votes: <input type="number" name="choices-1-votes" value="900"></li>
-<li>Order: <input type="number" name="choices-1-ORDER" value="2"></li>
-<li>Choice: <input type="text" name="choices-2-choice"></li>
-<li>Votes: <input type="number" name="choices-2-votes"></li>
-<li>Order: <input type="number" name="choices-2-ORDER"></li>""",
+            '<li>Choice: <input type="text" name="choices-0-choice" value="Calexico">'
+            "</li>"
+            '<li>Votes: <input type="number" name="choices-0-votes" value="100"></li>'
+            '<li>Order: <input type="number" name="choices-0-ORDER" value="1"></li>'
+            '<li>Choice: <input type="text" name="choices-1-choice" value="Fergie">'
+            "</li>"
+            '<li>Votes: <input type="number" name="choices-1-votes" value="900"></li>'
+            '<li>Order: <input type="number" name="choices-1-ORDER" value="2"></li>'
+            '<li>Choice: <input type="text" name="choices-2-choice"></li>'
+            '<li>Votes: <input type="number" name="choices-2-votes"></li>'
+            '<li>Order: <input type="number" name="choices-2-ORDER"></li>',
         )
         data = {
             "choices-TOTAL_FORMS": "3",  # the number of forms rendered
@@ -864,22 +870,25 @@ class FormsFormsetTestCase(SimpleTestCase):
         formset = ChoiceFormSet(initial=initial, auto_id=False, prefix="choices")
         self.assertHTMLEqual(
             "\n".join(form.as_ul() for form in formset.forms),
-            """<li>Choice: <input type="text" name="choices-0-choice" value="Calexico"></li>
-<li>Votes: <input type="number" name="choices-0-votes" value="100"></li>
-<li>Order: <input type="number" name="choices-0-ORDER" value="1"></li>
-<li>Delete: <input type="checkbox" name="choices-0-DELETE"></li>
-<li>Choice: <input type="text" name="choices-1-choice" value="Fergie"></li>
-<li>Votes: <input type="number" name="choices-1-votes" value="900"></li>
-<li>Order: <input type="number" name="choices-1-ORDER" value="2"></li>
-<li>Delete: <input type="checkbox" name="choices-1-DELETE"></li>
-<li>Choice: <input type="text" name="choices-2-choice" value="The Decemberists"></li>
-<li>Votes: <input type="number" name="choices-2-votes" value="500"></li>
-<li>Order: <input type="number" name="choices-2-ORDER" value="3"></li>
-<li>Delete: <input type="checkbox" name="choices-2-DELETE"></li>
-<li>Choice: <input type="text" name="choices-3-choice"></li>
-<li>Votes: <input type="number" name="choices-3-votes"></li>
-<li>Order: <input type="number" name="choices-3-ORDER"></li>
-<li>Delete: <input type="checkbox" name="choices-3-DELETE"></li>""",
+            '<li>Choice: <input type="text" name="choices-0-choice" value="Calexico">'
+            "</li>"
+            '<li>Votes: <input type="number" name="choices-0-votes" value="100"></li>'
+            '<li>Order: <input type="number" name="choices-0-ORDER" value="1"></li>'
+            '<li>Delete: <input type="checkbox" name="choices-0-DELETE"></li>'
+            '<li>Choice: <input type="text" name="choices-1-choice" value="Fergie">'
+            "</li>"
+            '<li>Votes: <input type="number" name="choices-1-votes" value="900"></li>'
+            '<li>Order: <input type="number" name="choices-1-ORDER" value="2"></li>'
+            '<li>Delete: <input type="checkbox" name="choices-1-DELETE"></li>'
+            '<li>Choice: <input type="text" name="choices-2-choice" '
+            'value="The Decemberists"></li>'
+            '<li>Votes: <input type="number" name="choices-2-votes" value="500"></li>'
+            '<li>Order: <input type="number" name="choices-2-ORDER" value="3"></li>'
+            '<li>Delete: <input type="checkbox" name="choices-2-DELETE"></li>'
+            '<li>Choice: <input type="text" name="choices-3-choice"></li>'
+            '<li>Votes: <input type="number" name="choices-3-votes"></li>'
+            '<li>Order: <input type="number" name="choices-3-ORDER"></li>'
+            '<li>Delete: <input type="checkbox" name="choices-3-DELETE"></li>',
         )
         # Let's delete Fergie, and put The Decemberists ahead of Calexico.
         data = {
diff --git a/tests/model_forms/tests.py b/tests/model_forms/tests.py
index eb9c2484dc..d2ce3348c5 100644
--- a/tests/model_forms/tests.py
+++ b/tests/model_forms/tests.py
@@ -1929,26 +1929,28 @@ class ModelFormBasicTests(TestCase):
         f = ArticleForm(auto_id=False)
         self.assertHTMLEqual(
             f.as_ul(),
-            """<li>Headline: <input type="text" name="headline" maxlength="50" required></li>
-<li>Slug: <input type="text" name="slug" maxlength="50" required></li>
-<li>Pub date: <input type="text" name="pub_date" required></li>
-<li>Writer: <select name="writer" required>
-<option value="" selected>---------</option>
-<option value="%s">Bob Woodward</option>
-<option value="%s">Mike Royko</option>
-</select></li>
-<li>Article: <textarea rows="10" cols="40" name="article" required></textarea></li>
-<li>Categories: <select multiple name="categories">
-<option value="%s">Entertainment</option>
-<option value="%s">It&#x27;s a test</option>
-<option value="%s">Third test</option>
-</select> </li>
-<li>Status: <select name="status">
-<option value="" selected>---------</option>
-<option value="1">Draft</option>
-<option value="2">Pending</option>
-<option value="3">Live</option>
-</select></li>"""
+            '<li>Headline: <input type="text" name="headline" maxlength="50" required>'
+            "</li>"
+            '<li>Slug: <input type="text" name="slug" maxlength="50" required></li>'
+            '<li>Pub date: <input type="text" name="pub_date" required></li>'
+            '<li>Writer: <select name="writer" required>'
+            '<option value="" selected>---------</option>'
+            '<option value="%s">Bob Woodward</option>'
+            '<option value="%s">Mike Royko</option>'
+            "</select></li>"
+            '<li>Article: <textarea rows="10" cols="40" name="article" required>'
+            "</textarea></li>"
+            '<li>Categories: <select multiple name="categories">'
+            '<option value="%s">Entertainment</option>'
+            '<option value="%s">It&#x27;s a test</option>'
+            '<option value="%s">Third test</option>'
+            "</select> </li>"
+            '<li>Status: <select name="status">'
+            '<option value="" selected>---------</option>'
+            '<option value="1">Draft</option>'
+            '<option value="2">Pending</option>'
+            '<option value="3">Live</option>'
+            "</select></li>"
             % (self.w_woodward.pk, self.w_royko.pk, self.c1.pk, self.c2.pk, self.c3.pk),
         )
 
@@ -1956,28 +1958,30 @@ class ModelFormBasicTests(TestCase):
         w_bernstein = Writer.objects.create(name="Carl Bernstein")
         self.assertHTMLEqual(
             f.as_ul(),
-            """<li>Headline: <input type="text" name="headline" maxlength="50" required></li>
-<li>Slug: <input type="text" name="slug" maxlength="50" required></li>
-<li>Pub date: <input type="text" name="pub_date" required></li>
-<li>Writer: <select name="writer" required>
-<option value="" selected>---------</option>
-<option value="%s">Bob Woodward</option>
-<option value="%s">Carl Bernstein</option>
-<option value="%s">Mike Royko</option>
-</select></li>
-<li>Article: <textarea rows="10" cols="40" name="article" required></textarea></li>
-<li>Categories: <select multiple name="categories">
-<option value="%s">Entertainment</option>
-<option value="%s">It&#x27;s a test</option>
-<option value="%s">Third test</option>
-<option value="%s">Fourth</option>
-</select></li>
-<li>Status: <select name="status">
-<option value="" selected>---------</option>
-<option value="1">Draft</option>
-<option value="2">Pending</option>
-<option value="3">Live</option>
-</select></li>"""
+            '<li>Headline: <input type="text" name="headline" maxlength="50" required>'
+            "</li>"
+            '<li>Slug: <input type="text" name="slug" maxlength="50" required></li>'
+            '<li>Pub date: <input type="text" name="pub_date" required></li>'
+            '<li>Writer: <select name="writer" required>'
+            '<option value="" selected>---------</option>'
+            '<option value="%s">Bob Woodward</option>'
+            '<option value="%s">Carl Bernstein</option>'
+            '<option value="%s">Mike Royko</option>'
+            "</select></li>"
+            '<li>Article: <textarea rows="10" cols="40" name="article" required>'
+            "</textarea></li>"
+            '<li>Categories: <select multiple name="categories">'
+            '<option value="%s">Entertainment</option>'
+            '<option value="%s">It&#x27;s a test</option>'
+            '<option value="%s">Third test</option>'
+            '<option value="%s">Fourth</option>'
+            "</select></li>"
+            '<li>Status: <select name="status">'
+            '<option value="" selected>---------</option>'
+            '<option value="1">Draft</option>'
+            '<option value="2">Pending</option>'
+            '<option value="3">Live</option>'
+            "</select></li>"
             % (
                 self.w_woodward.pk,
                 w_bernstein.pk,
diff --git a/tests/staticfiles_tests/test_forms.py b/tests/staticfiles_tests/test_forms.py
index d95fed43cc..ad662d7321 100644
--- a/tests/staticfiles_tests/test_forms.py
+++ b/tests/staticfiles_tests/test_forms.py
@@ -29,10 +29,11 @@ class StaticFilesFormsMediaTestCase(SimpleTestCase):
         )
         self.assertEqual(
             str(m),
-            """<link href="https://example.com/assets/path/to/css1" media="all" rel="stylesheet">
-<link href="/path/to/css2" media="all" rel="stylesheet">
-<script src="/path/to/js1"></script>
-<script src="http://media.other.com/path/to/js2"></script>
-<script src="https://secure.other.com/path/to/js3"></script>
-<script src="https://example.com/assets/relative/path/to/js4"></script>""",
+            '<link href="https://example.com/assets/path/to/css1" media="all" '
+            'rel="stylesheet">\n'
+            '<link href="/path/to/css2" media="all" rel="stylesheet">\n'
+            '<script src="/path/to/js1"></script>\n'
+            '<script src="http://media.other.com/path/to/js2"></script>\n'
+            '<script src="https://secure.other.com/path/to/js3"></script>\n'
+            '<script src="https://example.com/assets/relative/path/to/js4"></script>',
         )