diff --git a/tests/distinct_on_fields/tests.py b/tests/distinct_on_fields/tests.py
index e1365dab88..6bb518d2b1 100644
--- a/tests/distinct_on_fields/tests.py
+++ b/tests/distinct_on_fields/tests.py
@@ -1,6 +1,5 @@
 from django.db.models import Max
 from django.test import TestCase, skipUnlessDBFeature
-from django.test.utils import str_prefix
 
 from .models import Celebrity, Fan, Staff, StaffTag, Tag
 
@@ -78,8 +77,7 @@ class DistinctOnTests(TestCase):
             (
                 (Staff.objects.distinct('id').order_by('id', 'coworkers__name').
                     values_list('id', 'coworkers__name')),
-                [str_prefix("(1, %(_)s'p2')"), str_prefix("(2, %(_)s'p1')"),
-                 str_prefix("(3, %(_)s'p1')"), "(4, None)"]
+                ["(1, 'p2')", "(2, 'p1')", "(3, 'p1')", "(4, None)"]
             ),
         )
         for qset, expected in qsets:
diff --git a/tests/forms_tests/tests/test_forms.py b/tests/forms_tests/tests/test_forms.py
index dc70519dac..98c5ee8783 100644
--- a/tests/forms_tests/tests/test_forms.py
+++ b/tests/forms_tests/tests/test_forms.py
@@ -19,7 +19,6 @@ from django.forms.utils import ErrorList
 from django.http import QueryDict
 from django.template import Context, Template
 from django.test import SimpleTestCase
-from django.test.utils import str_prefix
 from django.utils.datastructures import MultiValueDict
 from django.utils.encoding import force_text
 from django.utils.html import format_html
@@ -2519,9 +2518,7 @@ Password: <input type="password" name="password" required />
         # Case 3: POST with valid data (the success message).)
         self.assertEqual(
             my_function('POST', {'username': 'adrian', 'password1': 'secret', 'password2': 'secret'}),
-            str_prefix(
-                "VALID: [('password1', %(_)s'secret'), ('password2', %(_)s'secret'), ('username', %(_)s'adrian')]"
-            )
+            "VALID: [('password1', 'secret'), ('password2', 'secret'), ('username', 'adrian')]"
         )
 
     def test_templates_with_forms(self):
diff --git a/tests/requests/tests.py b/tests/requests/tests.py
index 0dcaebbca5..ac331232aa 100644
--- a/tests/requests/tests.py
+++ b/tests/requests/tests.py
@@ -13,7 +13,7 @@ from django.http import (
 from django.http.request import split_domain_port
 from django.test import RequestFactory, SimpleTestCase, override_settings
 from django.test.client import FakePayload
-from django.test.utils import freeze_time, str_prefix
+from django.test.utils import freeze_time
 from django.utils.http import cookie_date, urlencode
 from django.utils.timezone import utc
 
@@ -57,17 +57,17 @@ class RequestsTests(SimpleTestCase):
         request.POST = {'post-key': 'post-value'}
         request.COOKIES = {'post-key': 'post-value'}
         request.META = {'post-key': 'post-value'}
-        self.assertEqual(repr(request), str_prefix("<HttpRequest: GET '/somepath/'>"))
+        self.assertEqual(repr(request), "<HttpRequest: GET '/somepath/'>")
 
     def test_httprequest_repr_invalid_method_and_path(self):
         request = HttpRequest()
-        self.assertEqual(repr(request), str_prefix("<HttpRequest>"))
+        self.assertEqual(repr(request), "<HttpRequest>")
         request = HttpRequest()
         request.method = "GET"
-        self.assertEqual(repr(request), str_prefix("<HttpRequest>"))
+        self.assertEqual(repr(request), "<HttpRequest>")
         request = HttpRequest()
         request.path = ""
-        self.assertEqual(repr(request), str_prefix("<HttpRequest>"))
+        self.assertEqual(repr(request), "<HttpRequest>")
 
     def test_wsgirequest(self):
         request = WSGIRequest({
@@ -156,13 +156,13 @@ class RequestsTests(SimpleTestCase):
 
     def test_wsgirequest_repr(self):
         request = WSGIRequest({'REQUEST_METHOD': 'get', 'wsgi.input': BytesIO(b'')})
-        self.assertEqual(repr(request), str_prefix("<WSGIRequest: GET '/'>"))
+        self.assertEqual(repr(request), "<WSGIRequest: GET '/'>")
         request = WSGIRequest({'PATH_INFO': '/somepath/', 'REQUEST_METHOD': 'get', 'wsgi.input': BytesIO(b'')})
         request.GET = {'get-key': 'get-value'}
         request.POST = {'post-key': 'post-value'}
         request.COOKIES = {'post-key': 'post-value'}
         request.META = {'post-key': 'post-value'}
-        self.assertEqual(repr(request), str_prefix("<WSGIRequest: GET '/somepath/'>"))
+        self.assertEqual(repr(request), "<WSGIRequest: GET '/somepath/'>")
 
     def test_wsgirequest_path_info(self):
         def wsgi_str(path_info, encoding='utf-8'):
diff --git a/tests/template_tests/filter_tests/test_make_list.py b/tests/template_tests/filter_tests/test_make_list.py
index 454b394d3b..17c4cac480 100644
--- a/tests/template_tests/filter_tests/test_make_list.py
+++ b/tests/template_tests/filter_tests/test_make_list.py
@@ -1,6 +1,5 @@
 from django.template.defaultfilters import make_list
 from django.test import SimpleTestCase
-from django.test.utils import str_prefix
 from django.utils.safestring import mark_safe
 
 from ..utils import setup
@@ -15,22 +14,22 @@ class MakeListTests(SimpleTestCase):
     @setup({'make_list01': '{% autoescape off %}{{ a|make_list }}{% endautoescape %}'})
     def test_make_list01(self):
         output = self.engine.render_to_string('make_list01', {"a": mark_safe("&")})
-        self.assertEqual(output, str_prefix("[%(_)s'&']"))
+        self.assertEqual(output, "['&']")
 
     @setup({'make_list02': '{{ a|make_list }}'})
     def test_make_list02(self):
         output = self.engine.render_to_string('make_list02', {"a": mark_safe("&")})
-        self.assertEqual(output, str_prefix("[%(_)s&#39;&amp;&#39;]"))
+        self.assertEqual(output, "[&#39;&amp;&#39;]")
 
     @setup({'make_list03': '{% autoescape off %}{{ a|make_list|stringformat:"s"|safe }}{% endautoescape %}'})
     def test_make_list03(self):
         output = self.engine.render_to_string('make_list03', {"a": mark_safe("&")})
-        self.assertEqual(output, str_prefix("[%(_)s'&']"))
+        self.assertEqual(output, "['&']")
 
     @setup({'make_list04': '{{ a|make_list|stringformat:"s"|safe }}'})
     def test_make_list04(self):
         output = self.engine.render_to_string('make_list04', {"a": mark_safe("&")})
-        self.assertEqual(output, str_prefix("[%(_)s'&']"))
+        self.assertEqual(output, "['&']")
 
 
 class FunctionTests(SimpleTestCase):
diff --git a/tests/test_client_regress/tests.py b/tests/test_client_regress/tests.py
index 4589ac33bd..d3263d07a6 100644
--- a/tests/test_client_regress/tests.py
+++ b/tests/test_client_regress/tests.py
@@ -15,7 +15,7 @@ from django.test import (
     Client, SimpleTestCase, TestCase, modify_settings, override_settings,
 )
 from django.test.client import RedirectCycleError, RequestFactory, encode_file
-from django.test.utils import ContextList, str_prefix
+from django.test.utils import ContextList
 from django.urls import NoReverseMatch, reverse
 from django.utils.translation import ugettext_lazy
 
@@ -595,21 +595,19 @@ class AssertFormErrorTests(SimpleTestCase):
             self.assertFormError(response, 'form', 'email', 'Some error.')
         except AssertionError as e:
             self.assertIn(
-                str_prefix(
-                    "The field 'email' on form 'form' in context 0 does not "
-                    "contain the error 'Some error.' (actual errors: "
-                    "[%(_)s'Enter a valid email address.'])"
-                ), str(e)
+                "The field 'email' on form 'form' in context 0 does not "
+                "contain the error 'Some error.' (actual errors: "
+                "['Enter a valid email address.'])",
+                str(e)
             )
         try:
             self.assertFormError(response, 'form', 'email', 'Some error.', msg_prefix='abc')
         except AssertionError as e:
             self.assertIn(
-                str_prefix(
-                    "abc: The field 'email' on form 'form' in context 0 does "
-                    "not contain the error 'Some error.' (actual errors: "
-                    "[%(_)s'Enter a valid email address.'])",
-                ), str(e)
+                "abc: The field 'email' on form 'form' in context 0 does "
+                "not contain the error 'Some error.' (actual errors: "
+                "['Enter a valid email address.'])",
+                str(e)
             )
 
     def test_unknown_nonfield_error(self):
@@ -719,10 +717,10 @@ class AssertFormsetErrorTests(SimpleTestCase):
     def test_unknown_error(self):
         "An assertion is raised if the field doesn't contain the specified error"
         for prefix, kwargs in self.msg_prefixes:
-            msg = str_prefix(
-                prefix + "The field 'email' on formset 'my_formset', form 0 "
+            msg = prefix + (
+                "The field 'email' on formset 'my_formset', form 0 "
                 "in context 0 does not contain the error 'Some error.' "
-                "(actual errors: [%(_)s'Enter a valid email address.'])"
+                "(actual errors: ['Enter a valid email address.'])"
             )
             with self.assertRaisesMessage(AssertionError, msg):
                 self.assertFormsetError(self.response_form_errors, 'my_formset', 0, 'email', 'Some error.', **kwargs)
@@ -743,10 +741,10 @@ class AssertFormsetErrorTests(SimpleTestCase):
     def test_unknown_nonfield_error(self):
         "An assertion is raised if the formsets non-field errors doesn't contain the provided error."
         for prefix, kwargs in self.msg_prefixes:
-            msg = str_prefix(
-                prefix + "The formset 'my_formset', form 0 in context 0 does not "
+            msg = prefix + (
+                "The formset 'my_formset', form 0 in context 0 does not "
                 "contain the non-field error 'Some error.' (actual errors: "
-                "[%(_)s'Non-field error.'])"
+                "['Non-field error.'])"
             )
             with self.assertRaisesMessage(AssertionError, msg):
                 self.assertFormsetError(self.response_form_errors, 'my_formset', 0, None, 'Some error.', **kwargs)
@@ -766,11 +764,10 @@ class AssertFormsetErrorTests(SimpleTestCase):
     def test_unknown_nonform_error(self):
         "An assertion is raised if the formsets non-form errors doesn't contain the provided error."
         for prefix, kwargs in self.msg_prefixes:
-            msg = str_prefix(
-                prefix +
+            msg = prefix + (
                 "The formset 'my_formset' in context 0 does not contain the "
-                "non-form error 'Some error.' (actual errors: [%(_)s'Forms "
-                "in a set must have distinct email addresses.'])"
+                "non-form error 'Some error.' (actual errors: ['Forms in a set "
+                "must have distinct email addresses.'])"
             )
             with self.assertRaisesMessage(AssertionError, msg):
                 self.assertFormsetError(
diff --git a/tests/validators/tests.py b/tests/validators/tests.py
index 124c2b1c68..ba7038094c 100644
--- a/tests/validators/tests.py
+++ b/tests/validators/tests.py
@@ -16,7 +16,6 @@ from django.core.validators import (
     validate_unicode_slug,
 )
 from django.test import SimpleTestCase
-from django.test.utils import str_prefix
 
 try:
     from PIL import Image  # noqa
@@ -314,18 +313,18 @@ def create_simple_test_method(validator, expected, value, num):
 class TestSimpleValidators(SimpleTestCase):
     def test_single_message(self):
         v = ValidationError('Not Valid')
-        self.assertEqual(str(v), str_prefix("[%(_)s'Not Valid']"))
-        self.assertEqual(repr(v), str_prefix("ValidationError([%(_)s'Not Valid'])"))
+        self.assertEqual(str(v), "['Not Valid']")
+        self.assertEqual(repr(v), "ValidationError(['Not Valid'])")
 
     def test_message_list(self):
         v = ValidationError(['First Problem', 'Second Problem'])
-        self.assertEqual(str(v), str_prefix("[%(_)s'First Problem', %(_)s'Second Problem']"))
-        self.assertEqual(repr(v), str_prefix("ValidationError([%(_)s'First Problem', %(_)s'Second Problem'])"))
+        self.assertEqual(str(v), "['First Problem', 'Second Problem']")
+        self.assertEqual(repr(v), "ValidationError(['First Problem', 'Second Problem'])")
 
     def test_message_dict(self):
         v = ValidationError({'first': ['First Problem']})
-        self.assertEqual(str(v), str_prefix("{%(_)s'first': [%(_)s'First Problem']}"))
-        self.assertEqual(repr(v), str_prefix("ValidationError({%(_)s'first': [%(_)s'First Problem']})"))
+        self.assertEqual(str(v), "{'first': ['First Problem']}")
+        self.assertEqual(repr(v), "ValidationError({'first': ['First Problem']})")
 
     def test_regex_validator_flags(self):
         with self.assertRaises(TypeError):