New upstream version 1.6.2

23 files changed, 204 insertions, 312 deletions

diff --git a/.github/CODEOWNERS b/.github/CODEOWNERS
new file mode 100644
index 0000000..553ceec
--- /dev/null
+++ b/.github/CODEOWNERS
@@ -0,0 +1,2 @@
+# Automatically request reviews from the synapse-core team when a pull request comes in.
+* @matrix-org/synapse-core
diff --git a/.github/workflows/tests.yaml b/.github/workflows/tests.yaml
new file mode 100644
index 0000000..c4bfa98
--- /dev/null
+++ b/.github/workflows/tests.yaml
@@ -0,0 +1,65 @@
+name: Tests
+on: [push, pull_request]
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        toxenv:
+          - "pep8"
+          - "black"
+          - "mypy"
+
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-python@v2
+        with:
+          python-version: '3.7'
+      - run: pip install tox
+      - run: tox -e ${{ matrix.toxenv }}
+
+  unittest:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python-version: ['3.7', '3.8', '3.9', '3.10', 'pypy-3.7']
+
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-python@v2
+        with:
+          python-version: ${{ matrix.python-version }}
+      - run: pip install tox
+      - run: tox -e py
+
+  packaging:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest, macos-latest]
+
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-python@v2
+      - run: python -m pip install tox
+      - run: tox -e packaging
+
+  macos-tests:
+    runs-on: macos-latest
+    strategy:
+      matrix:
+        python-version: ["3.8", "3.9", "3.10"]
+
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-python@v2
+        with:
+          python-version: ${{ matrix.python-version }}
+      - run: pip install tox
+      - run: tox -e py
+
diff --git a/.travis.yml b/.travis.yml
deleted file mode 100644
index a110082..0000000
--- a/.travis.yml
+++ /dev/null
@@ -1,40 +0,0 @@
-language: python
-
-# tell travis to cache ~/.cache/pip
-cache: pip
-
-matrix:
-  include:
-    - python: 3.6
-      env: TOXENV=packaging
-
-    - python: 3.6
-      env: TOXENV=pep8
-
-    - python: 3.6
-      env: TOXENV=black
-
-    - python: 3.5
-      env: TOXENV=py35
-
-    - python: 3.6
-      env: TOXENV=py36
-
-    - python: 3.7
-      env: TOXENV=py37
-
-    - python: 3.8
-      env: TOXENV=py38
-
-    - os: osx
-      language: generic
-      env: TOXENV=py38
-
-    - python: pypy3
-      env: TOXENV=pypy3
-
-install:
-- ./.travis/install.sh
-
-script:
-- tox
diff --git a/.travis/install.sh b/.travis/install.sh
deleted file mode 100755
index 6d55809..0000000
--- a/.travis/install.sh
+++ /dev/null
@@ -1,21 +0,0 @@
-#!/bin/bash
-
-set -xe
-
-if [[ $TRAVIS_OS_NAME == 'osx' ]]; then
-    # osx build uses a 'generic' language which doesn't come with pip
-    case "${TOXENV}" in
-        py38)
-            # for py38, use homebrew python, which comes with pip.
-            # see also https://docs.brew.sh/Homebrew-and-Python
-            brew upgrade python
-            pip3 install tox
-            ;;
-        *)
-            echo "TOXENV ${TOXENV} not supported on osx" >&2
-            exit 1
-            ;;
-    esac
-else
-    pip install tox
-fi
diff --git a/CHANGES.md b/CHANGES.md
index aaa9eb8..e652bb9 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,3 +1,14 @@
+Version 1.6.0 released 2022-03-04
+
+* `frozendict` is now an optional dependency; it is no longer required.
+
+Version 1.5.0 released 2021-10-20
+
+* Switch CI from Travis to Github Actions
+* Add code to handle frozendict implementations using c-extension
+* Add tests for Python 3.10
+* Remove outdated Debian packaging code
+
 Version 1.4.0 released 2020-09-03
 
 * Fix producing non-standard JSON for Infinity, -Infinity, and NaN. This could
diff --git a/MANIFEST.in b/MANIFEST.in
index 0ac1524..63f6c5b 100644
--- a/MANIFEST.in
+++ b/MANIFEST.in
@@ -3,5 +3,6 @@ include *.py
 include *.md
 include LICENSE
 include tox.ini
+include pyproject.toml
 prune .travis
 prune debian
diff --git a/README.rst b/README.rst
index a6887d6..af0c212 100644
--- a/README.rst
+++ b/README.rst
@@ -5,9 +5,6 @@ Canonical JSON
     :target: https://pypi.python.org/pypi/canonicaljson/
     :alt: Latest Version
 
-.. image:: https://img.shields.io/travis/matrix-org/python-canonicaljson.svg
-   :target: https://travis-ci.org/matrix-org/python-canonicaljson
-
 Features
 --------
 
@@ -20,7 +17,7 @@ Features
 * Encodes the JSON as UTF-8.
 * Can encode ``frozendict`` immutable dictionaries.
 
-Supports Python versions 3.5 and newer.
+Supports Python versions 3.7 and newer.
 
 .. _`RFC 7159`: https://tools.ietf.org/html/rfc7159
 
diff --git a/canonicaljson.py b/canonicaljson.py
index 8dee682..a2d8148 100644
--- a/canonicaljson.py
+++ b/canonicaljson.py
@@ -16,29 +16,53 @@
 # limitations under the License.
 
 import platform
+from typing import Any, Generator, Optional, Type
 
-from frozendict import frozendict
+try:
+    from typing import Protocol
+except ImportError:  # pragma: no cover
+    from typing_extensions import Protocol  # type: ignore[misc]
 
-__version__ = "1.4.0"
+frozendict_type: Optional[Type[Any]]
+try:
+    from frozendict import frozendict as frozendict_type
+except ImportError:
+    frozendict_type = None  # pragma: no cover
 
+__version__ = "1.6.2"
 
-def _default(obj):
-    if type(obj) is frozendict:
-        # fishing the protected dict out of the object is a bit nasty,
-        # but we don't really want the overhead of copying the dict.
-        return obj._dict
+
+def _default(obj: object) -> object:  # pragma: no cover
+    if type(obj) is frozendict_type:
+        # If frozendict is available and used, cast `obj` into a dict
+        return dict(obj)  # type: ignore[call-overload]
     raise TypeError(
         "Object of type %s is not JSON serializable" % obj.__class__.__name__
     )
 
 
+class Encoder(Protocol):  # pragma: no cover
+    def encode(self, data: object) -> str:
+        pass
+
+    def iterencode(self, data: object) -> Generator[str, None, None]:
+        pass
+
+    def __call__(self, *args: Any, **kwargs: Any) -> "Encoder":
+        pass
+
+
+class JsonLibrary(Protocol):
+    JSONEncoder: Encoder
+
+
 # Declare these in the module scope, but they get configured in
 # set_json_library.
-_canonical_encoder = None
-_pretty_encoder = None
+_canonical_encoder: Encoder = None  # type: ignore[assignment]
+_pretty_encoder: Encoder = None  # type: ignore[assignment]
 
 
-def set_json_library(json_lib):
+def set_json_library(json_lib: JsonLibrary) -> None:
     """
     Set the underlying JSON library that canonicaljson uses to json_lib.
 
@@ -57,59 +81,52 @@ def set_json_library(json_lib):
 
     global _pretty_encoder
     _pretty_encoder = json_lib.JSONEncoder(
-        ensure_ascii=False, allow_nan=False, indent=4, sort_keys=True, default=_default,
+        ensure_ascii=False,
+        allow_nan=False,
+        indent=4,
+        sort_keys=True,
+        default=_default,
     )
 
 
-def encode_canonical_json(json_object):
-    """Encodes the shortest UTF-8 JSON encoding with dictionary keys
-    lexicographically sorted by unicode code point.
-
-    Args:
-        json_object (dict): The JSON object to encode.
-
-    Returns:
-        bytes encoding the JSON object"""
-    s = _canonical_encoder.encode(json_object)
-    return s.encode("utf-8")
-
+def encode_canonical_json(data: object) -> bytes:
+    """Encodes the given `data` as a UTF-8 canonical JSON bytestring.
 
-def iterencode_canonical_json(json_object):
-    """Encodes the shortest UTF-8 JSON encoding with dictionary keys
+    This encoding is the shortest possible. Dictionary keys are
     lexicographically sorted by unicode code point.
+    """
+    s = _canonical_encoder.encode(data)
+    return s.encode("utf-8")
 
-    Args:
-        json_object (dict): The JSON object to encode.
 
-    Returns:
-        generator which yields bytes encoding the JSON object"""
-    for chunk in _canonical_encoder.iterencode(json_object):
-        yield chunk.encode("utf-8")
+def iterencode_canonical_json(data: object) -> Generator[bytes, None, None]:
+    """Iteratively encodes the given `data` as a UTF-8 canonical JSON bytestring.
 
+    This yields one or more bytestrings; concatenating them all together yields the
+    full encoding of `data`. Building up the encoding gradually in this way allows us to
+    encode large pieces of `data` without blocking other tasks.
 
-def encode_pretty_printed_json(json_object):
+    This encoding is the shortest possible. Dictionary keys are
+    lexicographically sorted by unicode code point.
     """
-    Encodes the JSON object dict as human readable UTF-8 bytes.
-
-    Args:
-        json_object (dict): The JSON object to encode.
-
-    Returns:
-        bytes encoding the JSON object"""
+    for chunk in _canonical_encoder.iterencode(data):
+        yield chunk.encode("utf-8")
 
-    return _pretty_encoder.encode(json_object).encode("utf-8")
 
+def encode_pretty_printed_json(data: object) -> bytes:
+    """Encodes the given `data` as a UTF-8 human-readable JSON bytestring."""
 
-def iterencode_pretty_printed_json(json_object):
-    """Encodes the JSON object dict as human readable UTF-8 bytes.
+    return _pretty_encoder.encode(data).encode("utf-8")
 
-    Args:
-        json_object (dict): The JSON object to encode.
 
-    Returns:
-        generator which yields bytes encoding the JSON object"""
+def iterencode_pretty_printed_json(data: object) -> Generator[bytes, None, None]:
+    """Iteratively encodes the given `data` as a UTF-8 human-readable JSON bytestring.
 
-    for chunk in _pretty_encoder.iterencode(json_object):
+    This yields one or more bytestrings; concatenating them all together yields the
+    full encoding of `data`. Building up the encoding gradually in this way allows us to
+    encode large pieces of `data` without blocking other tasks.
+    """
+    for chunk in _pretty_encoder.iterencode(data):
         yield chunk.encode("utf-8")
 
 
@@ -124,7 +141,7 @@ else:  # pragma: no cover
     #
     # Note that it seems performance is on par or better using json from the
     # standard library as of Python 3.7.
-    import simplejson as json
+    import simplejson as json  # type: ignore[no-redef]
 
 # Set the JSON library to the backwards compatible version.
 set_json_library(json)
diff --git a/debian/changelog b/debian/changelog
deleted file mode 100644
index 5178787..0000000
--- a/debian/changelog
+++ /dev/null
@@ -1,42 +0,0 @@
-python-canonicaljson (1.1.4) stable; urgency=medium
-
-  * Fix error when encoding non-BMP characters on UCS-2 python builds
-    (fixes issue #12).
-
- -- Richard van der Hoff <richard@matrix.org>  Wed, 23 May 2018 09:07:26 +0100
-
-python-canonicaljson (1.1.3) stable; urgency=medium
-
-  * Bump depencency on frozendict to >=1.0, to fix conflicts with older
-    versions.
-
- -- Richard van der Hoff <richard@matrix.org>  Fri, 13 Apr 2018 09:51:24 +0100
-
-python-canonicaljson (1.1.2) stable; urgency=medium
-
-  * Fix escaping of control characters U+0000 to U+001F AGAIN, which was STILL
-    broken in the previous release
-
- -- Richard van der Hoff <richard@matrix.org>  Thu, 12 Apr 2018 15:53:56 +0100
-
-python-canonicaljson (1.1.1) stable; urgency=medium
-
-  * Fix escaping of control characters U+0000 to U+001F, which was broken in
-    the previous release
-
- -- Richard van der Hoff <richard@matrix.org>  Wed, 11 Apr 2018 18:01:50 +0100
-
-python-canonicaljson (1.1.0) stable; urgency=medium
-
-  * Significant performance improvements
-    (https://github.com/matrix-org/python-canonicaljson/pull/7,
-    https://github.com/matrix-org/python-canonicaljson/pull/8,
-    https://github.com/matrix-org/python-canonicaljson/pull/9)
-
- -- Richard van der Hoff <richard@matrix.org>  Tue, 10 Apr 2018 16:42:19 +0100
-
-canonicaljson (1.0.0-1) wheezy; urgency=low
-
-  * source package automatically created by stdeb 0.6.0+git
-
- -- Erik Johnston <erikj@matrix.org>  Fri, 13 Nov 2015 14:47:18 +0000
diff --git a/debian/clean b/debian/clean
deleted file mode 100644
index 45149aa..0000000
--- a/debian/clean
+++ /dev/null
@@ -1 +0,0 @@
-*.egg-info/*
diff --git a/debian/compat b/debian/compat
deleted file mode 100644
index ec63514..0000000
--- a/debian/compat
+++ /dev/null
@@ -1 +0,0 @@
-9
diff --git a/debian/control b/debian/control
deleted file mode 100644
index e45aec8..0000000
--- a/debian/control
+++ /dev/null
@@ -1,56 +0,0 @@
-Source: python-canonicaljson
-Maintainer: Richard van der Hoff <richard@matrix.org>
-Section: python
-Priority: optional
-Build-Depends:
- debhelper (>= 9),
- dh-python,
- python-all (>= 2.6.6-3),
- python-setuptools (>= 0.6.24),
- python3-all,
- python3-setuptools (>= 0.6.24),
- python-frozendict (>= 0.4),
- python-simplejson (>= 3.6.5),
- python3-frozendict (>= 0.4),
- python3-simplejson (>= 3.6.5)
-Standards-Version: 3.9.7
-X-Python-Version: >= 2.7
-
-Package: python-canonicaljson
-Architecture: all
-Depends:
- python-frozendict (>= 0.4),
- python-simplejson (>= 3.6.5),
- ${misc:Depends},
- ${python:Depends}
-Provides: ${python:Provides}
-Description: canonical JSON implementation for Python 2
- Canonical JSON implementation for Python 2.
- .
- * Encodes objects and arrays as RFC 7159 JSON.
- * Sorts object keys so that you get the same result each time.
- * Has no inignificant whitespace to make the output as small as possible.
- * Escapes only the characters that must be escaped, U+0000 to U+0019 / U+0022 /
-   U+0056, to keep the output as small as possible.
- * Uses the shortest escape sequence for each escaped character.
- * Encodes the JSON as UTF-8.
- * Can encode frozendict immutable dictionaries.
-
-Package: python3-canonicaljson
-Architecture: all
-Depends:
- python3-frozendict (>= 0.4),
- python3-simplejson (>= 3.6.5),
- ${misc:Depends},
- ${python3:Depends}
-Description: canonical JSON implementation for Python 3
- Canonical JSON implementation for Python 3.
- .
- * Encodes objects and arrays as RFC 7159 JSON.
- * Sorts object keys so that you get the same result each time.
- * Has no inignificant whitespace to make the output as small as possible.
- * Escapes only the characters that must be escaped, U+0000 to U+0019 / U+0022 /
-   U+0056, to keep the output as small as possible.
- * Uses the shortest escape sequence for each escaped character.
- * Encodes the JSON as UTF-8.
- * Can encode frozendict immutable dictionaries.
diff --git a/debian/copyright b/debian/copyright
deleted file mode 100644
index a6ccf35..0000000
--- a/debian/copyright
+++ /dev/null
@@ -1,29 +0,0 @@
-Format: http://www.debian.org/doc/packaging-manuals/copyright-format/1.0/
-Upstream-Contact: Richard van der Hoff <richard@matrix.org>
-
-Files: *
-Copyright: 2014-2015 OpenMarket Ltd
-    2018 New Vector Ltd
-License: Apache-2.0
-
-Files: debian/*
-Copyright: 2014-2015 OpenMarket Ltd
-    2017 Andrew Shadura <andrewsh@debian.org>
-    2018 New Vector Ltd
-License: Apache-2.0
-
-License: Apache-2.0
- Licensed under the Apache License, Version 2.0 (the "License");
- you may not use this file except in compliance with the License.
- You may obtain a copy of the License at
- .
-     http://www.apache.org/licenses/LICENSE-2.0
- .
- Unless required by applicable law or agreed to in writing, software
- distributed under the License is distributed on an "AS IS" BASIS,
- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- See the License for the specific language governing permissions and
- limitations under the License.
- .
- On Debian systems, the complete text of the Apache License,
- version 2.0 can be found in ‘/usr/share/common-licenses/Apache-2.0’.
diff --git a/debian/python-canonicaljson.docs b/debian/python-canonicaljson.docs
deleted file mode 100644
index a1320b1..0000000
--- a/debian/python-canonicaljson.docs
+++ /dev/null
@@ -1 +0,0 @@
-README.rst
diff --git a/debian/python3-canonicaljson.docs b/debian/python3-canonicaljson.docs
deleted file mode 100644
index a1320b1..0000000
--- a/debian/python3-canonicaljson.docs
+++ /dev/null
@@ -1 +0,0 @@
-README.rst
diff --git a/debian/rules b/debian/rules
deleted file mode 100755
index f9fe4f0..0000000
--- a/debian/rules
+++ /dev/null
@@ -1,6 +0,0 @@
-#!/usr/bin/make -f
-
-export PYBUILD_NAME=canonicaljson
-
-%:
-	dh $@ --with python2,python3 --buildsystem=pybuild
diff --git a/debian/source/format b/debian/source/format
deleted file mode 100644
index 89ae9db..0000000
--- a/debian/source/format
+++ /dev/null
@@ -1 +0,0 @@
-3.0 (native)
diff --git a/debian/source/options b/debian/source/options
deleted file mode 100644
index 4d82e22..0000000
--- a/debian/source/options
+++ /dev/null
@@ -1 +0,0 @@
-extend-diff-ignore="\.egg-info"
\ No newline at end of file
diff --git a/pyproject.toml b/pyproject.toml
new file mode 100644
index 0000000..bd1d867
--- /dev/null
+++ b/pyproject.toml
@@ -0,0 +1,6 @@
+[tool.mypy]
+show_error_codes = true
+strict = true
+
+files = ["."]
+exclude = "setup.py"
diff --git a/releasing.md b/releasing.md
index a127f1b..73cb3ed 100644
--- a/releasing.md
+++ b/releasing.md
@@ -3,42 +3,10 @@ Releasing python-canonicaljson
 
 * bump version in `canonicaljson.py`
 * update changelog
-* update debian changelog:
-  * Add new entry: `dch -v <ver>`
-  * Mark as released: `dch --distribution stable -r`
 * Build and upload to pypi:
   * `rm -r dist`
   * `python setup.py sdist bdist_wheel`
   * `twine upload -s dist/*`
 * `git tag -s v<ver>`
 * `git push`
-* `git push --tags`
-* Follow instructions below to release debian packaging.
-
-Prerequisites for debian packaging
-----------------------------------
-
-```
-sudo apt-get install sbuild
-sudo apt-get install ubuntu-dev-tools # for mk-sbuild
-sudo sbuild-adduser $LOGNAME
-
-newgrp sbuild
-mk-sbuild stretch
-```
-
-If your kernel doesn't support `aufs`, you'll need to set `union-type=overlay`
-in `/etc/schroot/chroot.d/sbuild-stretch-amd64`.
-
-Debian release
---------------
-
-```
-# We need to build from a pristine copy of the repo (otherwise you end up with
-# your whole working copy in the source tarball), so:
-git clone git@github.com:matrix-org/python-canonicaljson.git -b v<ver> python-canonicaljson-clean
-
-cd python-canonicaljson-clean
-sbuild -s --arch-all -d stretch
-debsign
-```
+* `git push --tags`
\ No newline at end of file
diff --git a/setup.py b/setup.py
index 1c2cc94..fec43db 100755
--- a/setup.py
+++ b/setup.py
@@ -49,8 +49,13 @@ setup(
         # simplerjson versions before 3.14.0 had a bug with some characters
         # (e.g. \u2028) if ensure_ascii was set to false.
         "simplejson>=3.14.0",
-        "frozendict>=1.0",
+        # typing.Protocol was only added to the stdlib in Python 3.8
+        "typing_extensions>=4.0.0; python_version < '3.8'",
     ],
+    extras_require={
+        # frozendict support can be enabled using the `canonicaljson[frozendict]` syntax
+        "frozendict": ["frozendict>=1.0"],
+    },
     zip_safe=True,
     long_description=read_file(("README.rst",)),
     keywords="json",
@@ -58,7 +63,7 @@ setup(
     author_email="team@matrix.org",
     url="https://github.com/matrix-org/python-canonicaljson",
     license="Apache License, Version 2.0",
-    python_requires="~=3.5",
+    python_requires="~=3.7",
     classifiers=[
         "Development Status :: 5 - Production/Stable",
         "Intended Audience :: Developers",
diff --git a/test_canonicaljson.py b/test_canonicaljson.py
index 003d108..fc19922 100644
--- a/test_canonicaljson.py
+++ b/test_canonicaljson.py
@@ -14,34 +14,36 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+
 from math import inf, nan
 
 from canonicaljson import (
     encode_canonical_json,
     encode_pretty_printed_json,
+    frozendict_type,
     iterencode_canonical_json,
     iterencode_pretty_printed_json,
     set_json_library,
 )
 
-from frozendict import frozendict
-
 import unittest
 from unittest import mock
 
 
 class TestCanonicalJson(unittest.TestCase):
-    def test_encode_canonical(self):
+    def test_encode_canonical(self) -> None:
         self.assertEqual(encode_canonical_json({}), b"{}")
 
         # ctrl-chars should be encoded.
         self.assertEqual(
-            encode_canonical_json(u"text\u0003\r\n"), b'"text\\u0003\\r\\n"',
+            encode_canonical_json(u"text\u0003\r\n"),
+            b'"text\\u0003\\r\\n"',
         )
 
         # quotes and backslashes should be escaped.
         self.assertEqual(
-            encode_canonical_json(r'"\ test'), b'"\\"\\\\ test"',
+            encode_canonical_json(r'"\ test'),
+            b'"\\"\\\\ test"',
         )
 
         # non-ascii should come out utf8-encoded.
@@ -59,13 +61,14 @@ class TestCanonicalJson(unittest.TestCase):
         # but we need to watch out for 'u1234' after backslash, which should
         # get encoded to an escaped backslash, followed by u1234
         self.assertEqual(
-            encode_canonical_json(u"\\u1234"), b'"\\\\u1234"',
+            encode_canonical_json(u"\\u1234"),
+            b'"\\\\u1234"',
         )
 
         # Iteratively encoding should work.
         self.assertEqual(list(iterencode_canonical_json({})), [b"{}"])
 
-    def test_ascii(self):
+    def test_ascii(self) -> None:
         """
         Ensure the proper ASCII characters are escaped.
 
@@ -92,10 +95,10 @@ class TestCanonicalJson(unittest.TestCase):
         # And other characters are passed unescaped.
         unescaped = [0x20, 0x21] + list(range(0x23, 0x5C)) + list(range(0x5D, 0x7E))
         for c in unescaped:
-            c = chr(c)
-            self.assertEqual(encode_canonical_json(c), b'"' + c.encode("ascii") + b'"')
+            s = chr(c)
+            self.assertEqual(encode_canonical_json(s), b'"' + s.encode("ascii") + b'"')
 
-    def test_encode_pretty_printed(self):
+    def test_encode_pretty_printed(self) -> None:
         self.assertEqual(encode_pretty_printed_json({}), b"{}")
         self.assertEqual(list(iterencode_pretty_printed_json({})), [b"{}"])
 
@@ -105,15 +108,23 @@ class TestCanonicalJson(unittest.TestCase):
             b'{\n    "la merde amus\xc3\xa9e": "\xF0\x9F\x92\xA9"\n}',
         )
 
-    def test_frozen_dict(self):
+    @unittest.skipIf(
+        frozendict_type is None,
+        "If `frozendict` is not available, skip test",
+    )
+    def test_frozen_dict(self) -> None:
+        # For mypy's benefit:
+        assert frozendict_type is not None
         self.assertEqual(
-            encode_canonical_json(frozendict({"a": 1})), b'{"a":1}',
+            encode_canonical_json(frozendict_type({"a": 1})),
+            b'{"a":1}',
         )
         self.assertEqual(
-            encode_pretty_printed_json(frozendict({"a": 1})), b'{\n    "a": 1\n}'
+            encode_pretty_printed_json(frozendict_type({"a": 1})),
+            b'{\n    "a": 1\n}',
         )
 
-    def test_unknown_type(self):
+    def test_unknown_type(self) -> None:
         class Unknown(object):
             pass
 
@@ -124,9 +135,8 @@ class TestCanonicalJson(unittest.TestCase):
         with self.assertRaises(Exception):
             encode_pretty_printed_json(unknown_object)
 
-    def test_invalid_float_values(self):
-        """Infinity/-Infinity/NaN are not allowed in canonicaljson.
-        """
+    def test_invalid_float_values(self) -> None:
+        """Infinity/-Infinity/NaN are not allowed in canonicaljson."""
 
         with self.assertRaises(ValueError):
             encode_canonical_json(inf)
@@ -146,7 +156,7 @@ class TestCanonicalJson(unittest.TestCase):
         with self.assertRaises(ValueError):
             encode_pretty_printed_json(nan)
 
-    def test_set_json(self):
+    def test_set_json(self) -> None:
         """Ensure that changing the underlying JSON implementation works."""
         mock_json = mock.Mock(spec=["JSONEncoder"])
         mock_json.JSONEncoder.return_value.encode.return_value = "sentinel"
@@ -155,6 +165,6 @@ class TestCanonicalJson(unittest.TestCase):
             self.assertEqual(encode_canonical_json({}), b"sentinel")
         finally:
             # Reset the JSON library to whatever was originally set.
-            from canonicaljson import json
+            from canonicaljson import json  # type: ignore[attr-defined]
 
             set_json_library(json)
diff --git a/tox.ini b/tox.ini
index 74d6a79..00ae34c 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,13 +1,13 @@
 [tox]
-envlist = packaging, pep8, py35, py36, py37, py38, pypy3
+envlist = packaging, pep8, black, py37, py38, py39, py310, pypy3
 
 [testenv]
 deps =
     coverage
-    nose
+    nose2
 
 commands =
-    coverage run --source canonicaljson -m nose
+    coverage run --source canonicaljson -m nose2
     coverage report -m --fail-under 100
 
 [testenv:packaging]
@@ -16,13 +16,23 @@ deps =
 commands = check-manifest
 
 [testenv:pep8]
-basepython = python3.6
+basepython = python3.7
 deps =
     flake8
 commands = flake8 .
 
 [testenv:black]
-basepython = python3.6
+basepython = python3.7
 deps =
-    black
+    black==21.9b0
+    # Workaround black+click incompatability, see https://github.com/psf/black/issues/2964
+    click==8.0.4
 commands = python -m black --check --diff .
+
+[testenv:mypy]
+deps =
+    mypy==0.942
+    types-frozendict==2.0.8
+    types-simplejson==3.17.5
+    types-setuptools==57.4.14
+commands = mypy