Support Python 3.10

Fixes #1124.

5 files changed, 16 insertions, 12 deletions

diff --git a/.github/workflows/tox.yml b/.github/workflows/tox.yml
index e7e8afc..18306f7 100644
--- a/.github/workflows/tox.yml
+++ b/.github/workflows/tox.yml
@@ -20,20 +20,22 @@ jobs:
       fail-fast: false
       max-parallel: 4
       matrix:
-        tox-env: [py36, py37, py38, py39, pypy3, pygments]
+        tox-env: [py36, py37, py38, py39, py310, pypy3, pygments]
         include:
           - tox-env: py36
-            python-version: 3.6
+            python-version: '3.6'
           - tox-env: py37
-            python-version: 3.7
+            python-version: '3.7'
           - tox-env: py38
-            python-version: 3.8
+            python-version: '3.8'
           - tox-env: py39
-            python-version: 3.9
+            python-version: '3.9'
+          - tox-env: py310
+            python-version: '3.10'
           - tox-env: pypy3
             python-version: pypy3
           - tox-env: pygments
-            python-version: 3.7
+            python-version: '3.7'
 
     env:
       TOXENV: ${{ matrix.tox-env }}
diff --git a/docs/change_log/index.md b/docs/change_log/index.md
index 9700832..cec78ab 100644
--- a/docs/change_log/index.md
+++ b/docs/change_log/index.md
@@ -11,6 +11,7 @@ Under development: version 3.3.5 (a bug-fix release).
 * Don't process shebangs in fenced code blocks when using CodeHilite (#1156).
 * Improve email address validation for Automatic Links (#1165).
 * Ensure `<summary>` tags are parsed correctly (#1079).
+* Support Python 3.10 (#1124).
 
 Feb 24, 2021: version 3.3.4 (a bug-fix release).
 
diff --git a/markdown/util.py b/markdown/util.py
index b443e37..98cfbf7 100644
--- a/markdown/util.py
+++ b/markdown/util.py
@@ -29,10 +29,10 @@ from itertools import count
 
 from .pep562 import Pep562
 
-try:
+if sys.version_info >= (3, 10):
     from importlib import metadata
-except ImportError:
-    # <PY38 use backport
+else:
+    # <PY310 use backport
     import importlib_metadata as metadata
 
 PY37 = (3, 7) <= sys.version_info
@@ -85,7 +85,7 @@ Constants you probably do not need to change
 """
 
 # Only load extension entry_points once.
-INSTALLED_EXTENSIONS = metadata.entry_points().get('markdown.extensions', ())
+INSTALLED_EXTENSIONS = metadata.entry_points(group='markdown.extensions')
 RTL_BIDI_RANGES = (
     ('\u0590', '\u07FF'),
     # Hebrew (0590-05FF), Arabic (0600-06FF),
diff --git a/setup.py b/setup.py
index d18c1a7..7928d0b 100755
--- a/setup.py
+++ b/setup.py
@@ -74,7 +74,7 @@ setup(
     license='BSD License',
     packages=['markdown', 'markdown.extensions'],
     python_requires='>=3.6',
-    install_requires=["importlib-metadata;python_version<'3.8'"],
+    install_requires=["importlib-metadata>='4.4';python_version<'3.10'"],
     extras_require={
         'testing': [
             'coverage',
@@ -117,6 +117,7 @@ setup(
         'Programming Language :: Python :: 3.7',
         'Programming Language :: Python :: 3.8',
         'Programming Language :: Python :: 3.9',
+        'Programming Language :: Python :: 3.10',
         'Programming Language :: Python :: 3 :: Only',
         'Programming Language :: Python :: Implementation :: CPython',
         'Programming Language :: Python :: Implementation :: PyPy',
diff --git a/tox.ini b/tox.ini
index 851826a..62523f9 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,5 +1,5 @@
 [tox]
-envlist = py36, py37, py38, py39, pypy3, pygments, flake8, checkspelling, pep517check, checklinks
+envlist = py36, py37, py38, py39, py310, pypy3, pygments, flake8, checkspelling, pep517check, checklinks
 isolated_build = True
 
 [testenv]