diff --git a/docs/conf.py b/docs/conf.py
index cb57d42..0d6ec28 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -9,87 +9,88 @@
 # All configuration values have a default; values that are commented out
 # serve to show the default.
 
-import sys, os
+import os
+import sys
 
 # If extensions (or modules to document with autodoc) are in another directory,
 # add these directories to sys.path here. If the directory is relative to the
 # documentation root, use os.path.abspath to make it absolute, like shown here.
-sys.path.insert(0, os.path.abspath('..'))
+sys.path.insert(0, os.path.abspath(".."))
 
 # -- General configuration -----------------------------------------------------
 
 # If your documentation needs a minimal Sphinx version, state it here.
-#needs_sphinx = '1.0'
+# needs_sphinx = '1.0'
 
 # Add any Sphinx extension module names here, as strings. They can be extensions
 # coming with Sphinx (named 'sphinx.ext.*') or your custom ones.
 extensions = [
-    'hoverxref.extension',
-    'notfound.extension',
-    'sphinx.ext.autodoc',
-    'sphinx.ext.doctest',
-    'sphinx.ext.intersphinx',
-    'sphinx.ext.viewcode',
+    "hoverxref.extension",
+    "notfound.extension",
+    "sphinx.ext.autodoc",
+    "sphinx.ext.doctest",
+    "sphinx.ext.intersphinx",
+    "sphinx.ext.viewcode",
 ]
 
 # Add any paths that contain templates here, relative to this directory.
-templates_path = ['_templates']
+templates_path = ["_templates"]
 
 # The suffix of source filenames.
-source_suffix = '.rst'
+source_suffix = ".rst"
 
 # The encoding of source files.
-#source_encoding = 'utf-8-sig'
+# source_encoding = 'utf-8-sig'
 
 # The master toctree document.
-master_doc = 'index'
+master_doc = "index"
 
 # General information about the project.
-project = 'w3lib'
-copyright = '2014, w3lib developers'
+project = "w3lib"
+copyright = "2014, w3lib developers"
 
 # The version info for the project you're documenting, acts as replacement for
 # |version| and |release|, also used in various other places throughout the
 # built documents.
 #
 # The full version, including alpha/beta/rc tags.
-release = '2.1.2'
+release = "2.1.2"
 # The short X.Y version.
-version = '.'.join(release.split('.')[:2])
+version = ".".join(release.split(".")[:2])
 
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.
-#language = None
+# language = None
 
 # There are two options for replacing |today|: either, you set today to some
 # non-false value, then it is used:
-#today = ''
+# today = ''
 # Else, today_fmt is used as the format for a strftime call.
-#today_fmt = '%B %d, %Y'
+# today_fmt = '%B %d, %Y'
 
 # List of patterns, relative to source directory, that match files and
 # directories to ignore when looking for source files.
-exclude_patterns = ['_build']
+exclude_patterns = ["_build"]
 
 # The reST default role (used for this markup: `text`) to use for all documents.
-#default_role = None
+# default_role = None
 
 # If true, '()' will be appended to :func: etc. cross-reference text.
-#add_function_parentheses = True
+# add_function_parentheses = True
 
 # If true, the current module name will be prepended to all description
 # unit titles (such as .. function::).
-#add_module_names = True
+# add_module_names = True
 
 # If true, sectionauthor and moduleauthor directives will be shown in the
 # output. They are ignored by default.
-#show_authors = False
+# show_authors = False
 
 # The name of the Pygments (syntax highlighting) style to use.
-pygments_style = 'sphinx'
+pygments_style = "sphinx"
 
 # A list of ignored prefixes for module index sorting.
-#modindex_common_prefix = []
+# modindex_common_prefix = []
 
 
 # -- Options for HTML output ---------------------------------------------------
@@ -101,26 +102,26 @@
 # Theme options are theme-specific and customize the look and feel of a theme
 # further.  For a list of options available for each theme, see the
 # documentation.
-#html_theme_options = {}
+# html_theme_options = {}
 
 # Add any paths that contain custom themes here, relative to this directory.
-#html_theme_path = []
+# html_theme_path = []
 
 # The name for this set of Sphinx documents.  If None, it defaults to
 # "<project> v<release> documentation".
-#html_title = None
+# html_title = None
 
 # A shorter title for the navigation bar.  Default is the same as html_title.
-#html_short_title = None
+# html_short_title = None
 
 # The name of an image file (relative to this directory) to place at the top
 # of the sidebar.
-#html_logo = None
+# html_logo = None
 
 # The name of an image file (within the static path) to use as favicon of the
 # docs.  This file should be a Windows icon file (.ico) being 16x16 or 32x32
 # pixels large.
-#html_favicon = None
+# html_favicon = None
 
 # Add any paths that contain custom static files (such as style sheets) here,
 # relative to this directory. They are copied after the builtin static files,
@@ -129,101 +130,95 @@
 
 # If not '', a 'Last updated on:' timestamp is inserted at every page bottom,
 # using the given strftime format.
-#html_last_updated_fmt = '%b %d, %Y'
+# html_last_updated_fmt = '%b %d, %Y'
 
 # If true, SmartyPants will be used to convert quotes and dashes to
 # typographically correct entities.
-#html_use_smartypants = True
+# html_use_smartypants = True
 
 # Custom sidebar templates, maps document names to template names.
-#html_sidebars = {}
+# html_sidebars = {}
 
 # Additional templates that should be rendered to pages, maps page names to
 # template names.
-#html_additional_pages = {}
+# html_additional_pages = {}
 
 # If false, no module index is generated.
-#html_domain_indices = True
+# html_domain_indices = True
 
 # If false, no index is generated.
-#html_use_index = True
+# html_use_index = True
 
 # If true, the index is split into individual pages for each letter.
-#html_split_index = False
+# html_split_index = False
 
 # If true, links to the reST sources are added to the pages.
-#html_show_sourcelink = True
+# html_show_sourcelink = True
 
 # If true, "Created using Sphinx" is shown in the HTML footer. Default is True.
-#html_show_sphinx = True
+# html_show_sphinx = True
 
 # If true, "(C) Copyright ..." is shown in the HTML footer. Default is True.
-#html_show_copyright = True
+# html_show_copyright = True
 
 # If true, an OpenSearch description file will be output, and all pages will
 # contain a <link> tag referring to it.  The value of this option must be the
 # base URL from which the finished HTML is served.
-#html_use_opensearch = ''
+# html_use_opensearch = ''
 
 # This is the file name suffix for HTML files (e.g. ".xhtml").
-#html_file_suffix = None
+# html_file_suffix = None
 
 # Output file base name for HTML help builder.
-htmlhelp_basename = 'w3libdoc'
+htmlhelp_basename = "w3libdoc"
 
 
 # -- Options for LaTeX output --------------------------------------------------
 
 latex_elements = {
-# The paper size ('letterpaper' or 'a4paper').
-#'papersize': 'letterpaper',
-
-# The font size ('10pt', '11pt' or '12pt').
-#'pointsize': '10pt',
-
-# Additional stuff for the LaTeX preamble.
-#'preamble': '',
+    # The paper size ('letterpaper' or 'a4paper').
+    # 'papersize': 'letterpaper',
+    # The font size ('10pt', '11pt' or '12pt').
+    # 'pointsize': '10pt',
+    # Additional stuff for the LaTeX preamble.
+    # 'preamble': '',
 }
 
 # Grouping the document tree into LaTeX files. List of tuples
 # (source start file, target name, title, author, documentclass [howto/manual]).
 latex_documents = [
-  ('index', 'w3lib.tex', 'w3lib Documentation',
-   'w3lib developers', 'manual'),
+    ("index", "w3lib.tex", "w3lib Documentation", "w3lib developers", "manual"),
 ]
 
 # The name of an image file (relative to this directory) to place at the top of
 # the title page.
-#latex_logo = None
+# latex_logo = None
 
 # For "manual" documents, if this is true, then toplevel headings are parts,
 # not chapters.
-#latex_use_parts = False
+# latex_use_parts = False
 
 # If true, show page references after internal links.
-#latex_show_pagerefs = False
+# latex_show_pagerefs = False
 
 # If true, show URL addresses after external links.
-#latex_show_urls = False
+# latex_show_urls = False
 
 # Documents to append as an appendix to all manuals.
-#latex_appendices = []
+# latex_appendices = []
 
 # If false, no module index is generated.
-#latex_domain_indices = True
+# latex_domain_indices = True
 
 
 # -- Options for manual page output --------------------------------------------
 
 # One entry per manual page. List of tuples
 # (source start file, name, description, authors, manual section).
-man_pages = [
-    ('index', 'w3lib', 'w3lib Documentation',
-     ['w3lib developers'], 1)
-]
+man_pages = [("index", "w3lib", "w3lib Documentation", ["w3lib developers"], 1)]
 
 # If true, show URL addresses after external links.
-#man_show_urls = False
+# man_show_urls = False
 
 
 # -- Options for Texinfo output ------------------------------------------------
@@ -232,27 +227,33 @@
 # (source start file, target name, title, author,
 #  dir menu entry, description, category)
 texinfo_documents = [
-  ('index', 'w3lib', 'w3lib Documentation',
-   'w3lib developers', 'w3lib', 'One line description of project.',
-   'Miscellaneous'),
+    (
+        "index",
+        "w3lib",
+        "w3lib Documentation",
+        "w3lib developers",
+        "w3lib",
+        "One line description of project.",
+        "Miscellaneous",
+    ),
 ]
 
 # Documents to append as an appendix to all manuals.
-#texinfo_appendices = []
+# texinfo_appendices = []
 
 # If false, no module index is generated.
-#texinfo_domain_indices = True
+# texinfo_domain_indices = True
 
 # How to display URL addresses: 'footnote', 'no', or 'inline'.
-#texinfo_show_urls = 'footnote'
+# texinfo_show_urls = 'footnote'
 
 
 # Example configuration for intersphinx: refer to the Python standard library.
 intersphinx_mapping = {
-    'pytest': ('https://docs.pytest.org/en/latest', None),
-    'python': ('https://docs.python.org/3', None),
-    'scrapy': ('https://scrapy.readthedocs.io/en/latest', None),
-    'tox': ('https://tox.readthedocs.io/en/latest', None),
+    "pytest": ("https://docs.pytest.org/en/latest", None),
+    "python": ("https://docs.python.org/3", None),
+    "scrapy": ("https://scrapy.readthedocs.io/en/latest", None),
+    "tox": ("https://tox.readthedocs.io/en/latest", None),
 }
 
 
diff --git a/setup.py b/setup.py
index c8728de..9825882 100644
--- a/setup.py
+++ b/setup.py
@@ -1,5 +1,4 @@
-from setuptools import setup, find_packages
-
+from setuptools import find_packages, setup
 
 setup(
     name="w3lib",
diff --git a/tests/test_encoding.py b/tests/test_encoding.py
index 0389e78..2f59e28 100644
--- a/tests/test_encoding.py
+++ b/tests/test_encoding.py
@@ -1,11 +1,11 @@
 import codecs
 import unittest
-from typing import Optional, Union, List, Any
+from typing import Any, List, Optional, Union
 
 from w3lib.encoding import (
     html_body_declared_encoding,
-    http_content_type_encoding,
     html_to_unicode,
+    http_content_type_encoding,
     read_bom,
     resolve_encoding,
     to_unicode,
@@ -39,17 +39,17 @@ def test_bom(self):
         utf32le = b"\xff\xfe\x00\x00\x34\x6c\x00\x00"
         for string in (utf16be, utf16le, utf32be, utf32le):
             bom_encoding, bom = read_bom(string)
-            assert bom_encoding is not None
-            assert bom is not None
+            self.assertIsNotNone(bom_encoding)
+            self.assertIsNotNone(bom)
             decoded = string[len(bom) :].decode(bom_encoding)
             self.assertEqual(water_unicode, decoded)
         # Body without BOM
         enc, bom = read_bom(b"foo")
-        self.assertEqual(enc, None)
-        self.assertEqual(bom, None)
+        self.assertIsNone(enc)
+        self.assertIsNone(bom)
         # Empty body
         enc, bom = read_bom(b"")
-        self.assertEqual(enc, None)
+        self.assertIsNone(enc)
         self.assertEqual(bom, None)
 
     def test_http_encoding_header(self):
@@ -146,7 +146,8 @@ def _assert_encoding(
         expected_encoding: str,
         expected_unicode: Union[str, List[str]],
     ) -> None:
-        assert not isinstance(body, str)
+        if isinstance(body, str):
+            raise AssertionError("body must not be an instance of str")
         encoding, body_unicode = html_to_unicode(ct(content_type), body)
         self.assertTrue(isinstance(body_unicode, str))
         self.assertEqual(norm_encoding(encoding), norm_encoding(expected_encoding))
@@ -208,13 +209,13 @@ def test_replace_wrong_encoding(self):
         encoding, body_unicode = html_to_unicode(ct("utf-8"), b"PREFIX\xe3\xabSUFFIX")
         # XXX: Policy for replacing invalid chars may suffer minor variations
         # but it should always contain the unicode replacement char ('\ufffd')
-        assert "\ufffd" in body_unicode, repr(body_unicode)
-        assert "PREFIX" in body_unicode, repr(body_unicode)
-        assert "SUFFIX" in body_unicode, repr(body_unicode)
+        self.assertIn("\ufffd", body_unicode)
+        self.assertIn("PREFIX", body_unicode)
+        self.assertIn("SUFFIX", body_unicode)
 
         # Do not destroy html tags due to encoding bugs
         encoding, body_unicode = html_to_unicode(ct("utf-8"), b"\xf0<span>value</span>")
-        assert "<span>value</span>" in body_unicode, repr(body_unicode)
+        self.assertIn("<span>value</span>", body_unicode)
 
     def _assert_encoding_detected(
         self,
@@ -223,7 +224,8 @@ def _assert_encoding_detected(
         body: bytes,
         **kwargs: Any,
     ) -> None:
-        assert not isinstance(body, str)
+        if isinstance(body, str):
+            raise AssertionError("body must not be an instance of str")
         encoding, body_unicode = html_to_unicode(ct(content_type), body, **kwargs)
         self.assertTrue(isinstance(body_unicode, str))
         self.assertEqual(norm_encoding(encoding), norm_encoding(expected_encoding))
@@ -272,7 +274,7 @@ def test_python_crash(self):
         random.seed(42)
         buf = BytesIO()
         for i in range(150000):
-            buf.write(bytes([random.randint(0, 255)]))
+            buf.write(bytes([random.randint(0, 255)]))  # nosec
         to_unicode(buf.getvalue(), "utf-16-le")
         to_unicode(buf.getvalue(), "utf-16-be")
         to_unicode(buf.getvalue(), "utf-32-le")
diff --git a/tests/test_html.py b/tests/test_html.py
index cf4ec03..3fe42d6 100644
--- a/tests/test_html.py
+++ b/tests/test_html.py
@@ -16,10 +16,14 @@
 class RemoveEntitiesTest(unittest.TestCase):
     def test_returns_unicode(self):
         # make sure it always return uncode
-        assert isinstance(replace_entities(b"no entities"), str)
-        assert isinstance(replace_entities(b"Price: &pound;100!"), str)
-        assert isinstance(replace_entities("no entities"), str)
-        assert isinstance(replace_entities("Price: &pound;100!"), str)
+        if not isinstance(replace_entities(b"no entities"), str):
+            raise AssertionError()
+        if not isinstance(replace_entities(b"Price: &pound;100!"), str):
+            raise AssertionError()
+        if not isinstance(replace_entities("no entities"), str):
+            raise AssertionError()
+        if not isinstance(replace_entities("Price: &pound;100!"), str):
+            raise AssertionError()
 
     def test_regular(self):
         # regular conversions
@@ -105,8 +109,8 @@ def test_encoding(self):
 class ReplaceTagsTest(unittest.TestCase):
     def test_returns_unicode(self):
         # make sure it always return uncode
-        assert isinstance(replace_tags(b"no entities"), str)
-        assert isinstance(replace_tags("no entities"), str)
+        self.assertEqual(isinstance(replace_tags(b"no entities"), str), True)
+        self.assertEqual(isinstance(replace_tags("no entities"), str), True)
 
     def test_replace_tags(self):
         self.assertEqual(
@@ -127,10 +131,14 @@ def test_replace_tags_multiline(self):
 class RemoveCommentsTest(unittest.TestCase):
     def test_returns_unicode(self):
         # make sure it always return unicode
-        assert isinstance(remove_comments(b"without comments"), str)
-        assert isinstance(remove_comments(b"<!-- with comments -->"), str)
-        assert isinstance(remove_comments("without comments"), str)
-        assert isinstance(remove_comments("<!-- with comments -->"), str)
+        self.assertEqual(isinstance(remove_comments(b"without comments"), str), True)
+        self.assertEqual(
+            isinstance(remove_comments(b"<!-- with comments -->"), str), True
+        )
+        self.assertEqual(isinstance(remove_comments("without comments"), str), True)
+        self.assertEqual(
+            isinstance(remove_comments("<!-- with comments -->"), str), True
+        )
 
     def test_no_comments(self):
         # text without comments
@@ -157,16 +165,28 @@ def test_remove_comments(self):
 class RemoveTagsTest(unittest.TestCase):
     def test_returns_unicode(self):
         # make sure it always return unicode
-        assert isinstance(remove_tags(b"no tags"), str)
-        assert isinstance(remove_tags(b"no tags", which_ones=("p",)), str)
-        assert isinstance(remove_tags(b"<p>one tag</p>"), str)
-        assert isinstance(remove_tags(b"<p>one tag</p>", which_ones=("p",)), str)
-        assert isinstance(remove_tags(b"<a>link</a>", which_ones=("b",)), str)
-        assert isinstance(remove_tags("no tags"), str)
-        assert isinstance(remove_tags("no tags", which_ones=("p",)), str)
-        assert isinstance(remove_tags("<p>one tag</p>"), str)
-        assert isinstance(remove_tags("<p>one tag</p>", which_ones=("p",)), str)
-        assert isinstance(remove_tags("<a>link</a>", which_ones=("b",)), str)
+        self.assertEqual(isinstance(remove_tags(b"no tags"), str), True)
+        self.assertEqual(
+            isinstance(remove_tags(b"no tags", which_ones=("p",)), str), True
+        )
+        self.assertEqual(isinstance(remove_tags(b"<p>one tag</p>"), str), True)
+        self.assertEqual(
+            isinstance(remove_tags(b"<p>one tag</p>", which_ones=("p",)), str), True
+        )
+        self.assertEqual(
+            isinstance(remove_tags(b"<a>link</a>", which_ones=("b",)), str), True
+        )
+        self.assertEqual(isinstance(remove_tags("no tags"), str), True)
+        self.assertEqual(
+            isinstance(remove_tags("no tags", which_ones=("p",)), str), True
+        )
+        self.assertEqual(isinstance(remove_tags("<p>one tag</p>"), str), True)
+        self.assertEqual(
+            isinstance(remove_tags("<p>one tag</p>", which_ones=("p",)), str), True
+        )
+        self.assertEqual(
+            isinstance(remove_tags("<a>link</a>", which_ones=("b",)), str), True
+        )
 
     def test_remove_tags_without_tags(self):
         # text without tags
@@ -232,21 +252,37 @@ def test_uppercase_tags(self):
 class RemoveTagsWithContentTest(unittest.TestCase):
     def test_returns_unicode(self):
         # make sure it always return unicode
-        assert isinstance(remove_tags_with_content(b"no tags"), str)
-        assert isinstance(remove_tags_with_content(b"no tags", which_ones=("p",)), str)
-        assert isinstance(
-            remove_tags_with_content(b"<p>one tag</p>", which_ones=("p",)), str
+        self.assertEqual(isinstance(remove_tags_with_content(b"no tags"), str), True)
+        self.assertEqual(
+            isinstance(remove_tags_with_content(b"no tags", which_ones=("p",)), str),
+            True,
+        )
+        self.assertEqual(
+            isinstance(
+                remove_tags_with_content(b"<p>one tag</p>", which_ones=("p",)), str
+            ),
+            True,
         )
-        assert isinstance(
-            remove_tags_with_content(b"<a>link</a>", which_ones=("b",)), str
+        self.assertEqual(
+            isinstance(
+                remove_tags_with_content(b"<a>link</a>", which_ones=("b",)), str
+            ),
+            True,
         )
-        assert isinstance(remove_tags_with_content("no tags"), str)
-        assert isinstance(remove_tags_with_content("no tags", which_ones=("p",)), str)
-        assert isinstance(
-            remove_tags_with_content("<p>one tag</p>", which_ones=("p",)), str
+        self.assertEqual(isinstance(remove_tags_with_content("no tags"), str), True)
+        self.assertEqual(
+            isinstance(remove_tags_with_content("no tags", which_ones=("p",)), str),
+            True,
+        )
+        self.assertEqual(
+            isinstance(
+                remove_tags_with_content("<p>one tag</p>", which_ones=("p",)), str
+            ),
+            True,
         )
-        assert isinstance(
-            remove_tags_with_content("<a>link</a>", which_ones=("b",)), str
+        self.assertEqual(
+            isinstance(remove_tags_with_content("<a>link</a>", which_ones=("b",)), str),
+            True,
         )
 
     def test_without_tags(self):
@@ -289,13 +325,25 @@ def test_tags_with_shared_prefix(self):
 class ReplaceEscapeCharsTest(unittest.TestCase):
     def test_returns_unicode(self):
         # make sure it always return unicode
-        assert isinstance(replace_escape_chars(b"no ec"), str)
-        assert isinstance(replace_escape_chars(b"no ec", replace_by="str"), str)
-        assert isinstance(replace_escape_chars(b"no ec", replace_by="str"), str)
-        assert isinstance(replace_escape_chars(b"no ec", which_ones=("\n", "\t")), str)
-        assert isinstance(replace_escape_chars("no ec"), str)
-        assert isinstance(replace_escape_chars("no ec", replace_by="str"), str)
-        assert isinstance(replace_escape_chars("no ec", which_ones=("\n", "\t")), str)
+        self.assertEqual(isinstance(replace_escape_chars(b"no ec"), str), True)
+        self.assertEqual(
+            isinstance(replace_escape_chars(b"no ec", replace_by="str"), str), True
+        )
+        self.assertEqual(
+            isinstance(replace_escape_chars(b"no ec", replace_by="str"), str), True
+        )
+        self.assertEqual(
+            isinstance(replace_escape_chars(b"no ec", which_ones=("\n", "\t")), str),
+            True,
+        )
+        self.assertEqual(isinstance(replace_escape_chars("no ec"), str), True)
+        self.assertEqual(
+            isinstance(replace_escape_chars("no ec", replace_by="str"), str), True
+        )
+        self.assertEqual(
+            isinstance(replace_escape_chars("no ec", which_ones=("\n", "\t")), str),
+            True,
+        )
 
     def test_without_escape_chars(self):
         # text without escape chars
@@ -325,7 +373,6 @@ def test_with_escape_chars(self):
 
 
 class UnquoteMarkupTest(unittest.TestCase):
-
     sample_txt1 = """<node1>hi, this is sample text with entities: &amp; &copy;
 <![CDATA[although this is inside a cdata! &amp; &quot;]]></node1>"""
     sample_txt2 = (
@@ -335,8 +382,10 @@ class UnquoteMarkupTest(unittest.TestCase):
 
     def test_returns_unicode(self):
         # make sure it always return unicode
-        assert isinstance(unquote_markup(self.sample_txt1.encode("latin-1")), str)
-        assert isinstance(unquote_markup(self.sample_txt2), str)
+        self.assertEqual(
+            isinstance(unquote_markup(self.sample_txt1.encode("latin-1")), str), True
+        )
+        self.assertEqual(isinstance(unquote_markup(self.sample_txt2), str), True)
 
     def test_unquote_markup(self):
         self.assertEqual(
diff --git a/tests/test_http.py b/tests/test_http.py
index 76a1ff1..2125e9e 100644
--- a/tests/test_http.py
+++ b/tests/test_http.py
@@ -1,5 +1,6 @@
 import unittest
 from collections import OrderedDict
+
 from w3lib.http import (
     HeadersDictInput,
     basic_auth_header,
diff --git a/tests/test_url.py b/tests/test_url.py
index 2960d5e..a6c01e6 100644
--- a/tests/test_url.py
+++ b/tests/test_url.py
@@ -1,8 +1,8 @@
-import sys
 import os
+import sys
 import unittest
 from inspect import isclass
-from typing import Optional, Union, Type, Callable, Tuple, List
+from typing import Callable, List, Optional, Tuple, Type, Union
 from urllib.parse import urlparse
 
 import pytest
@@ -27,8 +27,8 @@
     path_to_file_uri,
     safe_download_url,
     safe_url_string,
-    url_query_parameter,
     url_query_cleaner,
+    url_query_parameter,
 )
 
 # Test cases for URL-to-safe-URL conversions with a URL and an encoding as
@@ -327,12 +327,18 @@ def _test_safe_url_func(
     if encoding is not None:
         kwargs["encoding"] = encoding
     if isclass(output) and issubclass(output, Exception):
-        with pytest.raises(output):
+        try:
             func(url, **kwargs)
+        except output:
+            pass
+        else:
+            raise AssertionError(f"Expected exception {output} was not raised.")
         return
     actual = func(url, **kwargs)
-    assert actual == output
-    assert func(actual, **kwargs) == output  # Idempotency
+    if actual != output:
+        raise AssertionError(f"Expected {output}, but got {actual}.")
+    if func(actual, **kwargs) != output:
+        raise AssertionError("Idempotency check failed.")
 
 
 def _test_safe_url_string(
@@ -364,9 +370,11 @@ def _test_safe_url_string(
 @pytest.mark.parametrize(
     "encoding,url,output",
     tuple(
-        case
-        if case[:2] not in KNOWN_SAFE_URL_STRING_ENCODING_ISSUES
-        else pytest.param(*case, marks=pytest.mark.xfail(strict=True))
+        (
+            case
+            if case[:2] not in KNOWN_SAFE_URL_STRING_ENCODING_ISSUES
+            else pytest.param(*case, marks=pytest.mark.xfail(strict=True))
+        )
         for case in SAFE_URL_ENCODING_CASES
     ),
 )
@@ -425,9 +433,11 @@ def test_safe_url_string_encoding(
 @pytest.mark.parametrize(
     "url,output",
     tuple(
-        case
-        if case[0] not in KNOWN_SAFE_URL_STRING_URL_ISSUES
-        else pytest.param(*case, marks=pytest.mark.xfail(strict=True))
+        (
+            case
+            if case[0] not in KNOWN_SAFE_URL_STRING_URL_ISSUES
+            else pytest.param(*case, marks=pytest.mark.xfail(strict=True))
+        )
         for case in SAFE_URL_URL_CASES
     ),
 )
@@ -713,7 +723,8 @@ def test_safe_url_string_preserve_nonfragment_hash(self):
 
     def test_safe_url_string_encode_idna_domain_with_port(self):
         self.assertEqual(
-            safe_url_string("http://新华网.中国:80"), "http://xn--xkrr14bows.xn--fiqs8s:80"
+            safe_url_string("http://新华网.中国:80"),
+            "http://xn--xkrr14bows.xn--fiqs8s:80",
         )
 
     def test_safe_url_string_encode_idna_domain_with_username_password_and_port_number(
@@ -1134,8 +1145,12 @@ def test_canonicalize_url(self):
         )
 
     def test_return_str(self):
-        assert isinstance(canonicalize_url("http://www.example.com"), str)
-        assert isinstance(canonicalize_url(b"http://www.example.com"), str)
+        self.assertEqual(
+            isinstance(canonicalize_url("http://www.example.com"), str), True
+        )
+        self.assertEqual(
+            isinstance(canonicalize_url(b"http://www.example.com"), str), True
+        )
 
     def test_append_missing_path(self):
         self.assertEqual(
diff --git a/w3lib/encoding.py b/w3lib/encoding.py
index 7d46d78..c5c7526 100644
--- a/w3lib/encoding.py
+++ b/w3lib/encoding.py
@@ -1,13 +1,14 @@
 """
 Functions for handling encoding of web pages
 """
-import re
+
 import codecs
 import encodings
+import re
 from typing import Callable, Match, Optional, Tuple, Union, cast
 
-from w3lib._types import AnyUnicodeError, StrOrBytes
 import w3lib.util
+from w3lib._types import AnyUnicodeError, StrOrBytes
 
 _HEADER_ENCODING_RE = re.compile(r"charset=([\w-]+)", re.I)
 
@@ -51,7 +52,13 @@ def http_content_type_encoding(content_type: Optional[str]) -> Optional[str]:
 # pylint: disable=consider-using-f-string
 _BODY_ENCODING_PATTERN = (
     r"<\s*(?:meta%s(?:(?:\s+%s|\s+%s){2}|\s+%s)|\?xml\s[^>]+%s|body)"
-    % (_SKIP_ATTRS, _HTTPEQUIV_RE, _CONTENT_RE, _CONTENT2_RE, _XML_ENCODING_RE)
+    % (
+        _SKIP_ATTRS,
+        _HTTPEQUIV_RE,
+        _CONTENT_RE,
+        _CONTENT2_RE,
+        _XML_ENCODING_RE,
+    )
 )
 _BODY_ENCODING_STR_RE = re.compile(_BODY_ENCODING_PATTERN, re.I | re.VERBOSE)
 _BODY_ENCODING_BYTES_RE = re.compile(
diff --git a/w3lib/html.py b/w3lib/html.py
index f0f0184..760c0da 100644
--- a/w3lib/html.py
+++ b/w3lib/html.py
@@ -4,12 +4,12 @@
 
 import re
 from html.entities import name2codepoint
-from typing import Iterable, Match, AnyStr, Optional, Pattern, Tuple, Union
+from typing import AnyStr, Iterable, Match, Optional, Pattern, Tuple, Union
 from urllib.parse import urljoin
 
-from w3lib.util import to_unicode
-from w3lib.url import safe_url_string
 from w3lib._types import StrOrBytes
+from w3lib.url import safe_url_string
+from w3lib.util import to_unicode
 
 _ent_re = re.compile(
     r"&((?P<named>[a-z\d]+)|#(?P<dec>\d+)|#x(?P<hex>[a-f\d]+))(?P<semicolon>;?)",
diff --git a/w3lib/http.py b/w3lib/http.py
index a3e4e17..bdb3f66 100644
--- a/w3lib/http.py
+++ b/w3lib/http.py
@@ -1,5 +1,6 @@
 from base64 import b64encode
-from typing import Any, List, MutableMapping, Optional, AnyStr, Sequence, Union, Mapping
+from typing import Any, AnyStr, List, Mapping, MutableMapping, Optional, Sequence, Union
+
 from w3lib.util import to_bytes, to_unicode
 
 HeadersDictInput = Mapping[bytes, Union[Any, Sequence[bytes]]]
diff --git a/w3lib/url.py b/w3lib/url.py
index 485e694..52cf6ad 100644
--- a/w3lib/url.py
+++ b/w3lib/url.py
@@ -2,6 +2,7 @@
 This module contains general purpose URL functions not found in the standard
 library.
 """
+
 import base64
 import codecs
 import os
@@ -9,7 +10,6 @@
 import re
 import string
 from typing import (
-    cast,
     Callable,
     Dict,
     List,
@@ -18,12 +18,15 @@
     Sequence,
     Tuple,
     Union,
+    cast,
 )
+from urllib.parse import _coerce_args  # type: ignore
 from urllib.parse import (
+    ParseResult,
     parse_qs,
     parse_qsl,
-    ParseResult,
     quote,
+    unquote,
     unquote_to_bytes,
     urldefrag,
     urlencode,
@@ -31,15 +34,13 @@
     urlsplit,
     urlunparse,
     urlunsplit,
-    unquote,
 )
-from urllib.parse import _coerce_args  # type: ignore
 from urllib.request import pathname2url, url2pathname
 
-from .util import to_unicode
 from ._infra import _ASCII_TAB_OR_NEWLINE, _C0_CONTROL_OR_SPACE
 from ._types import AnyUnicodeError, StrOrBytes
 from ._url import _SPECIAL_SCHEMES
+from .util import to_unicode
 
 
 # error handling function for bytes-to-Unicode decoding errors with URLs
diff --git a/w3lib/util.py b/w3lib/util.py
index 70f4ef5..61426e8 100644
--- a/w3lib/util.py
+++ b/w3lib/util.py
@@ -1,5 +1,5 @@
-from warnings import warn
 from typing import Optional
+from warnings import warn
 
 from w3lib._types import StrOrBytes