Merge pull request #896 from fredrikt/ft-enable_mypy

Bump Python to 3.9, enable mypy configuration, and fix initial issues reported.

10 files changed, 196 insertions, 246 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0aa41dbd..dfe114b7 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,11 @@
 # Changelog
 
+## 7.4.0 (2023-XX-XX)
+
+- Add mypy configuration
+- Bump Python to 3.9
+
+
 ## 7.3.0 (2023-02-14)
 
 - During metadata generation, render extensions both for EntityDescriptor and IdPSSODescriptor
diff --git a/poetry.lock b/poetry.lock
index e70158eb..334b3eb4 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -116,12 +116,10 @@ files = [
 
 [package.dependencies]
 click = ">=8.0.0"
-dataclasses = {version = ">=0.6", markers = "python_version < \"3.7\""}
 mypy-extensions = ">=0.4.3"
 pathspec = ">=0.9.0"
 platformdirs = ">=2"
 tomli = {version = ">=1.1.0", markers = "python_full_version < \"3.11.0a7\""}
-typed-ast = {version = ">=1.4.2", markers = "python_version < \"3.8\" and implementation_name == \"cpython\""}
 typing-extensions = {version = ">=3.10.0.0", markers = "python_version < \"3.10\""}
 
 [package.extras]
@@ -248,7 +246,6 @@ files = [
 
 [package.dependencies]
 colorama = {version = "*", markers = "platform_system == \"Windows\""}
-importlib-metadata = {version = "*", markers = "python_version < \"3.8\""}
 
 [[package]]
 name = "colorama"
@@ -372,18 +369,6 @@ test-randomorder = ["pytest-randomly"]
 tox = ["tox"]
 
 [[package]]
-name = "dataclasses"
-version = "0.8"
-description = "A backport of the dataclasses module for Python 3.6"
-category = "dev"
-optional = false
-python-versions = ">=3.6, <3.7"
-files = [
-    {file = "dataclasses-0.8-py3-none-any.whl", hash = "sha256:0201d89fa866f68c8ebd9d08ee6ff50c0b255f8ec63a71c16fda7af82bb887bf"},
-    {file = "dataclasses-0.8.tar.gz", hash = "sha256:8479067f342acf957dc82ec415d355ab5edb7e7646b90dc6e2fd1d96ad084c97"},
-]
-
-[[package]]
 name = "decorator"
 version = "5.1.1"
 description = "Decorators for Humans"
@@ -475,7 +460,6 @@ files = [
 ]
 
 [package.dependencies]
-importlib-metadata = {version = ">=1.1.0,<4.3", markers = "python_version < \"3.8\""}
 mccabe = ">=0.7.0,<0.8.0"
 pycodestyle = ">=2.9.0,<2.10.0"
 pyflakes = ">=2.5.0,<2.6.0"
@@ -527,10 +511,7 @@ files = [
 
 [package.dependencies]
 Flake8 = ">=5"
-TOMLi = [
-    {version = "*", markers = "python_version < \"3.11\""},
-    {version = "<2", markers = "python_version < \"3.7\""},
-]
+TOMLi = {version = "*", markers = "python_version < \"3.11\""}
 
 [package.extras]
 dev = ["pyTest", "pyTest-cov"]
@@ -560,45 +541,6 @@ files = [
 ]
 
 [[package]]
-name = "importlib-metadata"
-version = "4.2.0"
-description = "Read metadata from Python packages"
-category = "main"
-optional = false
-python-versions = ">=3.6"
-files = [
-    {file = "importlib_metadata-4.2.0-py3-none-any.whl", hash = "sha256:057e92c15bc8d9e8109738a48db0ccb31b4d9d5cfbee5a8670879a30be66304b"},
-    {file = "importlib_metadata-4.2.0.tar.gz", hash = "sha256:b7e52a1f8dec14a75ea73e0891f3060099ca1d8e6a462a4dff11c3e119ea1b31"},
-]
-
-[package.dependencies]
-typing-extensions = {version = ">=3.6.4", markers = "python_version < \"3.8\""}
-zipp = ">=0.5"
-
-[package.extras]
-docs = ["jaraco.packaging (>=8.2)", "rst.linker (>=1.9)", "sphinx"]
-testing = ["flufl.flake8", "importlib-resources (>=1.3)", "packaging", "pep517", "pyfakefs", "pytest (>=4.6)", "pytest-black (>=0.3.7)", "pytest-checkdocs (>=2.4)", "pytest-cov", "pytest-enabler (>=1.0.1)", "pytest-flake8", "pytest-mypy"]
-
-[[package]]
-name = "importlib-resources"
-version = "5.4.0"
-description = "Read resources from Python packages"
-category = "main"
-optional = false
-python-versions = ">=3.6"
-files = [
-    {file = "importlib_resources-5.4.0-py3-none-any.whl", hash = "sha256:33a95faed5fc19b4bc16b29a6eeae248a3fe69dd55d4d229d2b480e23eeaad45"},
-    {file = "importlib_resources-5.4.0.tar.gz", hash = "sha256:d756e2f85dd4de2ba89be0b21dba2a3bbec2e871a42a3a16719258a11f87506b"},
-]
-
-[package.dependencies]
-zipp = {version = ">=3.1.0", markers = "python_version < \"3.10\""}
-
-[package.extras]
-docs = ["jaraco.packaging (>=8.2)", "rst.linker (>=1.9)", "sphinx"]
-testing = ["pytest (>=6)", "pytest-black (>=0.3.7)", "pytest-checkdocs (>=2.4)", "pytest-cov", "pytest-enabler (>=1.0.1)", "pytest-flake8", "pytest-mypy"]
-
-[[package]]
 name = "iniconfig"
 version = "1.1.1"
 description = "iniconfig: brain-dead simple config-ini parsing"
@@ -623,48 +565,9 @@ files = [
 ]
 
 [package.dependencies]
-decorator = {version = "*", markers = "python_version >= \"3.6\""}
-ipython = [
-    {version = ">=7.16.3,<7.17.0", markers = "python_version == \"3.6\""},
-    {version = ">=7.31.1", markers = "python_version > \"3.6\""},
-]
-tomli = {version = "*", markers = "python_version >= \"3.6\" and python_version < \"3.11\""}
-
-[[package]]
-name = "ipython"
-version = "7.16.3"
-description = "IPython: Productive Interactive Computing"
-category = "dev"
-optional = false
-python-versions = ">=3.6"
-files = [
-    {file = "ipython-7.16.3-py3-none-any.whl", hash = "sha256:c0427ed8bc33ac481faf9d3acf7e84e0010cdaada945e0badd1e2e74cc075833"},
-    {file = "ipython-7.16.3.tar.gz", hash = "sha256:5ac47dc9af66fc2f5530c12069390877ae372ac905edca75a92a6e363b5d7caa"},
-]
-
-[package.dependencies]
-appnope = {version = "*", markers = "sys_platform == \"darwin\""}
-backcall = "*"
-colorama = {version = "*", markers = "sys_platform == \"win32\""}
-decorator = "*"
-jedi = ">=0.10,<=0.17.2"
-pexpect = {version = "*", markers = "sys_platform != \"win32\""}
-pickleshare = "*"
-prompt-toolkit = ">=2.0.0,<3.0.0 || >3.0.0,<3.0.1 || >3.0.1,<3.1.0"
-pygments = "*"
-setuptools = ">=18.5"
-traitlets = ">=4.2"
-
-[package.extras]
-all = ["Sphinx (>=1.3)", "ipykernel", "ipyparallel", "ipywidgets", "nbconvert", "nbformat", "nose (>=0.10.1)", "notebook", "numpy (>=1.14)", "pygments", "qtconsole", "requests", "testpath"]
-doc = ["Sphinx (>=1.3)"]
-kernel = ["ipykernel"]
-nbconvert = ["nbconvert"]
-nbformat = ["nbformat"]
-notebook = ["ipywidgets", "notebook"]
-parallel = ["ipyparallel"]
-qtconsole = ["qtconsole"]
-test = ["ipykernel", "nbformat", "nose (>=0.10.1)", "numpy (>=1.14)", "pygments", "requests", "testpath"]
+decorator = {version = "*", markers = "python_version > \"3.6\""}
+ipython = {version = ">=7.31.1", markers = "python_version > \"3.6\""}
+tomli = {version = "*", markers = "python_version > \"3.6\" and python_version < \"3.11\""}
 
 [[package]]
 name = "ipython"
@@ -704,18 +607,6 @@ qtconsole = ["qtconsole"]
 test = ["ipykernel", "nbformat", "nose (>=0.10.1)", "numpy (>=1.17)", "pygments", "requests", "testpath"]
 
 [[package]]
-name = "ipython-genutils"
-version = "0.2.0"
-description = "Vestigial utilities from IPython"
-category = "dev"
-optional = false
-python-versions = "*"
-files = [
-    {file = "ipython_genutils-0.2.0-py2.py3-none-any.whl", hash = "sha256:72dd37233799e619666c9f639a9da83c34013a73e8bbc79a7a6348d93c61fab8"},
-    {file = "ipython_genutils-0.2.0.tar.gz", hash = "sha256:eb2e116e75ecef9d4d228fdc66af54269afa26ab4463042e33785b887c628ba8"},
-]
-
-[[package]]
 name = "isort"
 version = "5.10.1"
 description = "A Python utility / library to sort Python imports."
@@ -735,25 +626,6 @@ requirements-deprecated-finder = ["pip-api", "pipreqs"]
 
 [[package]]
 name = "jedi"
-version = "0.17.2"
-description = "An autocompletion tool for Python that can be used for text editors."
-category = "dev"
-optional = false
-python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.*"
-files = [
-    {file = "jedi-0.17.2-py2.py3-none-any.whl", hash = "sha256:98cc583fa0f2f8304968199b01b6b4b94f469a1f4a74c1560506ca2a211378b5"},
-    {file = "jedi-0.17.2.tar.gz", hash = "sha256:86ed7d9b750603e4ba582ea8edc678657fb4007894a12bcf6f4bb97892f31d20"},
-]
-
-[package.dependencies]
-parso = ">=0.7.0,<0.8.0"
-
-[package.extras]
-qa = ["flake8 (==3.7.9)"]
-testing = ["Django (<3.1)", "colorama", "docopt", "pytest (>=3.9.0,<5.0.0)"]
-
-[[package]]
-name = "jedi"
 version = "0.18.2"
 description = "An autocompletion tool for Python that can be used for text editors."
 category = "dev"
@@ -897,6 +769,53 @@ files = [
 ]
 
 [[package]]
+name = "mypy"
+version = "1.0.0"
+description = "Optional static typing for Python"
+category = "dev"
+optional = false
+python-versions = ">=3.7"
+files = [
+    {file = "mypy-1.0.0-cp310-cp310-macosx_10_9_x86_64.whl", hash = "sha256:e0626db16705ab9f7fa6c249c017c887baf20738ce7f9129da162bb3075fc1af"},
+    {file = "mypy-1.0.0-cp310-cp310-macosx_11_0_arm64.whl", hash = "sha256:1ace23f6bb4aec4604b86c4843276e8fa548d667dbbd0cb83a3ae14b18b2db6c"},
+    {file = "mypy-1.0.0-cp310-cp310-manylinux_2_17_x86_64.manylinux2014_x86_64.whl", hash = "sha256:87edfaf344c9401942883fad030909116aa77b0fa7e6e8e1c5407e14549afe9a"},
+    {file = "mypy-1.0.0-cp310-cp310-musllinux_1_1_x86_64.whl", hash = "sha256:0ab090d9240d6b4e99e1fa998c2d0aa5b29fc0fb06bd30e7ad6183c95fa07593"},
+    {file = "mypy-1.0.0-cp310-cp310-win_amd64.whl", hash = "sha256:7cc2c01dfc5a3cbddfa6c13f530ef3b95292f926329929001d45e124342cd6b7"},
+    {file = "mypy-1.0.0-cp311-cp311-macosx_10_9_x86_64.whl", hash = "sha256:14d776869a3e6c89c17eb943100f7868f677703c8a4e00b3803918f86aafbc52"},
+    {file = "mypy-1.0.0-cp311-cp311-macosx_11_0_arm64.whl", hash = "sha256:bb2782a036d9eb6b5a6efcdda0986774bf798beef86a62da86cb73e2a10b423d"},
+    {file = "mypy-1.0.0-cp311-cp311-manylinux_2_17_x86_64.manylinux2014_x86_64.whl", hash = "sha256:5cfca124f0ac6707747544c127880893ad72a656e136adc935c8600740b21ff5"},
+    {file = "mypy-1.0.0-cp311-cp311-musllinux_1_1_x86_64.whl", hash = "sha256:8845125d0b7c57838a10fd8925b0f5f709d0e08568ce587cc862aacce453e3dd"},
+    {file = "mypy-1.0.0-cp311-cp311-win_amd64.whl", hash = "sha256:01b1b9e1ed40544ef486fa8ac022232ccc57109f379611633ede8e71630d07d2"},
+    {file = "mypy-1.0.0-cp37-cp37m-macosx_10_9_x86_64.whl", hash = "sha256:c7cf862aef988b5fbaa17764ad1d21b4831436701c7d2b653156a9497d92c83c"},
+    {file = "mypy-1.0.0-cp37-cp37m-manylinux_2_17_x86_64.manylinux2014_x86_64.whl", hash = "sha256:5cd187d92b6939617f1168a4fe68f68add749902c010e66fe574c165c742ed88"},
+    {file = "mypy-1.0.0-cp37-cp37m-musllinux_1_1_x86_64.whl", hash = "sha256:4e5175026618c178dfba6188228b845b64131034ab3ba52acaffa8f6c361f805"},
+    {file = "mypy-1.0.0-cp37-cp37m-win_amd64.whl", hash = "sha256:2f6ac8c87e046dc18c7d1d7f6653a66787a4555085b056fe2d599f1f1a2a2d21"},
+    {file = "mypy-1.0.0-cp38-cp38-macosx_10_9_x86_64.whl", hash = "sha256:7306edca1c6f1b5fa0bc9aa645e6ac8393014fa82d0fa180d0ebc990ebe15964"},
+    {file = "mypy-1.0.0-cp38-cp38-macosx_11_0_arm64.whl", hash = "sha256:3cfad08f16a9c6611e6143485a93de0e1e13f48cfb90bcad7d5fde1c0cec3d36"},
+    {file = "mypy-1.0.0-cp38-cp38-manylinux_2_17_x86_64.manylinux2014_x86_64.whl", hash = "sha256:67cced7f15654710386e5c10b96608f1ee3d5c94ca1da5a2aad5889793a824c1"},
+    {file = "mypy-1.0.0-cp38-cp38-musllinux_1_1_x86_64.whl", hash = "sha256:a86b794e8a56ada65c573183756eac8ac5b8d3d59daf9d5ebd72ecdbb7867a43"},
+    {file = "mypy-1.0.0-cp38-cp38-win_amd64.whl", hash = "sha256:50979d5efff8d4135d9db293c6cb2c42260e70fb010cbc697b1311a4d7a39ddb"},
+    {file = "mypy-1.0.0-cp39-cp39-macosx_10_9_x86_64.whl", hash = "sha256:3ae4c7a99e5153496243146a3baf33b9beff714464ca386b5f62daad601d87af"},
+    {file = "mypy-1.0.0-cp39-cp39-macosx_11_0_arm64.whl", hash = "sha256:5e398652d005a198a7f3c132426b33c6b85d98aa7dc852137a2a3be8890c4072"},
+    {file = "mypy-1.0.0-cp39-cp39-manylinux_2_17_x86_64.manylinux2014_x86_64.whl", hash = "sha256:be78077064d016bc1b639c2cbcc5be945b47b4261a4f4b7d8923f6c69c5c9457"},
+    {file = "mypy-1.0.0-cp39-cp39-musllinux_1_1_x86_64.whl", hash = "sha256:92024447a339400ea00ac228369cd242e988dd775640755fa4ac0c126e49bb74"},
+    {file = "mypy-1.0.0-cp39-cp39-win_amd64.whl", hash = "sha256:fe523fcbd52c05040c7bee370d66fee8373c5972171e4fbc323153433198592d"},
+    {file = "mypy-1.0.0-py3-none-any.whl", hash = "sha256:2efa963bdddb27cb4a0d42545cd137a8d2b883bd181bbc4525b568ef6eca258f"},
+    {file = "mypy-1.0.0.tar.gz", hash = "sha256:f34495079c8d9da05b183f9f7daec2878280c2ad7cc81da686ef0b484cea2ecf"},
+]
+
+[package.dependencies]
+mypy-extensions = ">=0.4.3"
+tomli = {version = ">=1.1.0", markers = "python_version < \"3.11\""}
+typing-extensions = ">=3.10"
+
+[package.extras]
+dmypy = ["psutil (>=4.0)"]
+install-types = ["pip"]
+python2 = ["typed-ast (>=1.4.0,<2)"]
+reports = ["lxml"]
+
+[[package]]
 name = "mypy-extensions"
 version = "1.0.0"
 description = "Type system extensions for programs checked with the mypy type checker."
@@ -925,21 +844,6 @@ pyparsing = ">=2.0.2,<3.0.5 || >3.0.5"
 
 [[package]]
 name = "parso"
-version = "0.7.1"
-description = "A Python Parser"
-category = "dev"
-optional = false
-python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*"
-files = [
-    {file = "parso-0.7.1-py2.py3-none-any.whl", hash = "sha256:97218d9159b2520ff45eb78028ba8b50d2bc61dcc062a9682666f2dc4bd331ea"},
-    {file = "parso-0.7.1.tar.gz", hash = "sha256:caba44724b994a8a5e086460bb212abc5a8bc46951bf4a9a1210745953622eb9"},
-]
-
-[package.extras]
-testing = ["docopt", "pytest (>=3.0.7)"]
-
-[[package]]
-name = "parso"
 version = "0.8.3"
 description = "A Python Parser"
 category = "dev"
@@ -1041,9 +945,6 @@ files = [
     {file = "pluggy-1.0.0.tar.gz", hash = "sha256:4224373bacce55f955a878bf9cfa763c1e360858e330072059e10bad68531159"},
 ]
 
-[package.dependencies]
-importlib-metadata = {version = ">=0.12", markers = "python_version < \"3.8\""}
-
 [package.extras]
 dev = ["pre-commit", "tox"]
 testing = ["pytest", "pytest-benchmark"]
@@ -1313,7 +1214,6 @@ files = [
 atomicwrites = {version = ">=1.0", markers = "sys_platform == \"win32\""}
 attrs = ">=19.2.0"
 colorama = {version = "*", markers = "sys_platform == \"win32\""}
-importlib-metadata = {version = ">=0.12", markers = "python_version < \"3.8\""}
 iniconfig = "*"
 packaging = "*"
 pluggy = ">=0.12,<2.0"
@@ -1641,7 +1541,6 @@ files = [
 [package.dependencies]
 colorama = {version = ">=0.4.1", markers = "platform_system == \"Windows\""}
 filelock = ">=3.0.0"
-importlib-metadata = {version = ">=0.12", markers = "python_version < \"3.8\""}
 packaging = ">=14"
 pluggy = ">=0.12.0"
 py = ">=1.4.17"
@@ -1655,79 +1554,130 @@ testing = ["flaky (>=3.4.0)", "freezegun (>=0.3.11)", "pathlib2 (>=2.3.3)", "psu
 
 [[package]]
 name = "traitlets"
-version = "4.3.3"
-description = "Traitlets Python config system"
+version = "5.9.0"
+description = "Traitlets Python configuration system"
+category = "dev"
+optional = false
+python-versions = ">=3.7"
+files = [
+    {file = "traitlets-5.9.0-py3-none-any.whl", hash = "sha256:9e6ec080259b9a5940c797d58b613b5e31441c2257b87c2e795c5228ae80d2d8"},
+    {file = "traitlets-5.9.0.tar.gz", hash = "sha256:f6cde21a9c68cf756af02035f72d5a723bf607e862e7be33ece505abf4a3bad9"},
+]
+
+[package.extras]
+docs = ["myst-parser", "pydata-sphinx-theme", "sphinx"]
+test = ["argcomplete (>=2.0)", "pre-commit", "pytest", "pytest-mock"]
+
+[[package]]
+name = "types-docutils"
+version = "0.19.1.3"
+description = "Typing stubs for docutils"
 category = "dev"
 optional = false
 python-versions = "*"
 files = [
-    {file = "traitlets-4.3.3-py2.py3-none-any.whl", hash = "sha256:70b4c6a1d9019d7b4f6846832288f86998aa3b9207c6821f3578a6a6a467fe44"},
-    {file = "traitlets-4.3.3.tar.gz", hash = "sha256:d023ee369ddd2763310e4c3eae1ff649689440d4ae59d7485eb4cfbbe3e359f7"},
+    {file = "types-docutils-0.19.1.3.tar.gz", hash = "sha256:36fe30de56f1ece1a9f7a990d47daa781b5af831d2b3f2dcb7dfd01b857cc3d4"},
+    {file = "types_docutils-0.19.1.3-py3-none-any.whl", hash = "sha256:d608e6b91ccf0e8e01c586a0af5b0e0462382d3be65b734af82d40c9d010735d"},
+]
+
+[[package]]
+name = "types-pyopenssl"
+version = "23.0.0.3"
+description = "Typing stubs for pyOpenSSL"
+category = "dev"
+optional = false
+python-versions = "*"
+files = [
+    {file = "types-pyOpenSSL-23.0.0.3.tar.gz", hash = "sha256:6ca54d593f8b946f9570f9ed7457c41da3b518feff5e344851941a6209bea62b"},
+    {file = "types_pyOpenSSL-23.0.0.3-py3-none-any.whl", hash = "sha256:847ab17a16475a882dc29898648a6a35ad0d3e11a5bba5aa8ab2f3435a8647cb"},
 ]
 
 [package.dependencies]
-decorator = "*"
-ipython-genutils = "*"
-six = "*"
+cryptography = ">=35.0.0"
 
-[package.extras]
-test = ["mock", "pytest"]
+[[package]]
+name = "types-python-dateutil"
+version = "2.8.19.6"
+description = "Typing stubs for python-dateutil"
+category = "dev"
+optional = false
+python-versions = "*"
+files = [
+    {file = "types-python-dateutil-2.8.19.6.tar.gz", hash = "sha256:4a6f4cc19ce4ba1a08670871e297bf3802f55d4f129e6aa2443f540b6cf803d2"},
+    {file = "types_python_dateutil-2.8.19.6-py3-none-any.whl", hash = "sha256:cfb7d31021c6bce6f3362c69af6e3abb48fe3e08854f02487e844ff910deec2a"},
+]
 
 [[package]]
-name = "traitlets"
-version = "5.9.0"
-description = "Traitlets Python configuration system"
+name = "types-pytz"
+version = "2022.7.1.0"
+description = "Typing stubs for pytz"
 category = "dev"
 optional = false
-python-versions = ">=3.7"
+python-versions = "*"
 files = [
-    {file = "traitlets-5.9.0-py3-none-any.whl", hash = "sha256:9e6ec080259b9a5940c797d58b613b5e31441c2257b87c2e795c5228ae80d2d8"},
-    {file = "traitlets-5.9.0.tar.gz", hash = "sha256:f6cde21a9c68cf756af02035f72d5a723bf607e862e7be33ece505abf4a3bad9"},
+    {file = "types-pytz-2022.7.1.0.tar.gz", hash = "sha256:918f9c3e7a950ba7e7d6f84b18a7cacabc8886cb7125fb1927ff1c752b4b59de"},
+    {file = "types_pytz-2022.7.1.0-py3-none-any.whl", hash = "sha256:10ec7d009a02340f1cecd654ac03f0c29b6088a03b63d164401fc52df45936b2"},
 ]
 
-[package.extras]
-docs = ["myst-parser", "pydata-sphinx-theme", "sphinx"]
-test = ["argcomplete (>=2.0)", "pre-commit", "pytest", "pytest-mock"]
+[[package]]
+name = "types-requests"
+version = "2.28.11.12"
+description = "Typing stubs for requests"
+category = "dev"
+optional = false
+python-versions = "*"
+files = [
+    {file = "types-requests-2.28.11.12.tar.gz", hash = "sha256:fd530aab3fc4f05ee36406af168f0836e6f00f1ee51a0b96b7311f82cb675230"},
+    {file = "types_requests-2.28.11.12-py3-none-any.whl", hash = "sha256:dbc2933635860e553ffc59f5e264264981358baffe6342b925e3eb8261f866ee"},
+]
+
+[package.dependencies]
+types-urllib3 = "<1.27"
 
 [[package]]
-name = "typed-ast"
-version = "1.5.4"
-description = "a fork of Python 2 and 3 ast modules with type comment support"
+name = "types-setuptools"
+version = "67.2.0.1"
+description = "Typing stubs for setuptools"
 category = "dev"
 optional = false
-python-versions = ">=3.6"
+python-versions = "*"
+files = [
+    {file = "types-setuptools-67.2.0.1.tar.gz", hash = "sha256:07648088bc2cbf0f2745107d394e619ba2a747f68a5904e6e4089c0cb8322065"},
+    {file = "types_setuptools-67.2.0.1-py3-none-any.whl", hash = "sha256:f15b2924122dca5f99a9f6a96a872145721373fe1bb6d656cf269c2a8b73a74b"},
+]
+
+[package.dependencies]
+types-docutils = "*"
+
+[[package]]
+name = "types-six"
+version = "1.16.21.4"
+description = "Typing stubs for six"
+category = "dev"
+optional = false
+python-versions = "*"
+files = [
+    {file = "types-six-1.16.21.4.tar.gz", hash = "sha256:daaf1b506137d37257fad7a747857c57d5331611919d0d94b8195a06bdbc02af"},
+    {file = "types_six-1.16.21.4-py3-none-any.whl", hash = "sha256:3849354bd07b9274436aaa7d5d834594d8f0aa74581f88c632188c58f2abed23"},
+]
+
+[[package]]
+name = "types-urllib3"
+version = "1.26.25.5"
+description = "Typing stubs for urllib3"
+category = "dev"
+optional = false
+python-versions = "*"
 files = [
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-    {file = "typed_ast-1.5.4-cp39-cp39-macosx_10_9_x86_64.whl", hash = "sha256:4879da6c9b73443f97e731b617184a596ac1235fe91f98d279a7af36c796da35"},
-    {file = "typed_ast-1.5.4-cp39-cp39-macosx_11_0_arm64.whl", hash = "sha256:3e123d878ba170397916557d31c8f589951e353cc95fb7f24f6bb69adc1a8a97"},
-    {file = "typed_ast-1.5.4-cp39-cp39-manylinux_2_17_aarch64.manylinux2014_aarch64.whl", hash = "sha256:ebd9d7f80ccf7a82ac5f88c521115cc55d84e35bf8b446fcd7836eb6b98929a3"},
-    {file = "typed_ast-1.5.4-cp39-cp39-manylinux_2_5_x86_64.manylinux1_x86_64.manylinux_2_12_x86_64.manylinux2010_x86_64.whl", hash = "sha256:98f80dee3c03455e92796b58b98ff6ca0b2a6f652120c263efdba4d6c5e58f72"},
-    {file = "typed_ast-1.5.4-cp39-cp39-win_amd64.whl", hash = "sha256:0fdbcf2fef0ca421a3f5912555804296f0b0960f0418c440f5d6d3abb549f3e1"},
-    {file = "typed_ast-1.5.4.tar.gz", hash = "sha256:39e21ceb7388e4bb37f4c679d72707ed46c2fbf2a5609b8b8ebc4b067d977df2"},
+    {file = "types-urllib3-1.26.25.5.tar.gz", hash = "sha256:5630e578246d170d91ebe3901788cd28d53c4e044dc2e2488e3b0d55fb6895d8"},
+    {file = "types_urllib3-1.26.25.5-py3-none-any.whl", hash = "sha256:e8f25c8bb85cde658c72ee931e56e7abd28803c26032441eea9ff4a4df2b0c31"},
 ]
 
 [[package]]
 name = "typing-extensions"
 version = "4.1.1"
 description = "Backported and Experimental Type Hints for Python 3.6+"
-category = "main"
+category = "dev"
 optional = false
 python-versions = ">=3.6"
 files = [
@@ -1767,8 +1717,6 @@ files = [
 [package.dependencies]
 distlib = ">=0.3.1,<1"
 filelock = ">=3.2,<4"
-importlib-metadata = {version = ">=0.12", markers = "python_version < \"3.8\""}
-importlib-resources = {version = ">=1.0", markers = "python_version < \"3.7\""}
 platformdirs = ">=2,<3"
 
 [package.extras]
@@ -1824,22 +1772,6 @@ dev = ["Sphinx", "coverage", "elementpath (>=2.4.0,<3.0.0)", "flake8", "jinja2",
 docs = ["Sphinx", "elementpath (>=2.4.0,<3.0.0)", "jinja2", "sphinx-rtd-theme"]
 
 [[package]]
-name = "zipp"
-version = "3.6.0"
-description = "Backport of pathlib-compatible object wrapper for zip files"
-category = "main"
-optional = false
-python-versions = ">=3.6"
-files = [
-    {file = "zipp-3.6.0-py3-none-any.whl", hash = "sha256:9fe5ea21568a0a70e50f273397638d39b03353731e6cbbb3fd8502a33fec40bc"},
-    {file = "zipp-3.6.0.tar.gz", hash = "sha256:71c644c5369f4a6e07636f0aa966270449561fcea2e3d6747b8d23efaa9d7832"},
-]
-
-[package.extras]
-docs = ["jaraco.packaging (>=8.2)", "rst.linker (>=1.9)", "sphinx"]
-testing = ["func-timeout", "jaraco.itertools", "pytest (>=4.6)", "pytest-black (>=0.3.7)", "pytest-checkdocs (>=2.4)", "pytest-cov", "pytest-enabler (>=1.0.1)", "pytest-flake8", "pytest-mypy"]
-
-[[package]]
 name = "zope-interface"
 version = "5.5.2"
 description = "Interfaces for Python"
@@ -1898,5 +1830,5 @@ s2repoze = ["paste", "repoze.who", "zope.interface"]
 
 [metadata]
 lock-version = "2.0"
-python-versions = "^3.6.2"
-content-hash = "35d49afe7b4c13990ebf30816368f5cf12c651c22ae9c882b1a922d4a7e12c0f"
+python-versions = "^3.9"
+content-hash = "a13573a313282527140c0f524bf455edcffa750e7c3da6a0e9c601a9b1e351df"
diff --git a/pyproject.toml b/pyproject.toml
index e7d66b9a..0a1785ff 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -37,7 +37,7 @@ merge_metadata = "saml2.tools.merge_metadata:main"
 parse_xsd2 = "saml2.tools.parse_xsd2:main"
 
 [tool.poetry.dependencies]
-python = "^3.6.2"
+python = "^3.9"
 cryptography = ">=3.1"
 defusedxml = "*"
 importlib-metadata = {version = ">=1.7.0", python = "<3.8"}
@@ -66,6 +66,13 @@ Flake8-pyproject = "^1.1.0.post0"
 flake8-bugbear = "^22.8.23"
 flake8-logging-format = "^0.7.5"
 ipdb = "^0.13.9"
+mypy = "^1.0.0"
+types-pyopenssl = "^23.0.0.3"
+types-python-dateutil = "^2.8.19.6"
+types-pytz = "^2022.7.1.0"
+types-setuptools = "^67.2.0.1"
+types-six = "^1.16.21.4"
+types-requests = "^2.28.11.12"
 
 [tool.poetry.group.test]
 optional = true
@@ -225,15 +232,16 @@ src_paths = [
     'test',
 ]
 
-# XXX TODO
-#[tool.mypy]
-#pretty = true
-#check_untyped_defs = true
-#ignore_errors = false
-#ignore_missing_imports = true
-#show_error_codes = true
-#strict_optional = true
-#warn_unused_ignores = true
-#warn_redundant_casts = true
-#warn_unused_configs = true
-#warn_unreachable = true
+[tool.mypy]
+pretty = true
+check_untyped_defs = false
+ignore_errors = false
+ignore_missing_imports = true
+show_error_codes = true
+strict_optional = true
+warn_unused_ignores = true
+warn_redundant_casts = true
+warn_unused_configs = true
+warn_unreachable = true
+install_types = true
+non_interactive = true
diff --git a/src/saml2/__init__.py b/src/saml2/__init__.py
index 0397a365..01067b4b 100644
--- a/src/saml2/__init__.py
+++ b/src/saml2/__init__.py
@@ -17,6 +17,9 @@
 """
 
 import logging
+from typing import Any
+from typing import Optional
+from typing import Union
 from xml.etree import ElementTree
 
 import defusedxml.ElementTree
@@ -433,14 +436,14 @@ class SamlBase(ExtensionContainer):
     nodes into ExtensionElements.
     """
 
-    c_children = {}
-    c_attributes = {}
-    c_attribute_type = {}
-    c_child_order = []
-    c_cardinality = {}
-    c_any = None
-    c_any_attribute = None
-    c_value_type = None
+    c_children: Any = {}
+    c_attributes: Any = {}
+    c_attribute_type: Any = {}
+    c_child_order: list[str] = []
+    c_cardinality: dict[str, dict[str, int]] = {}
+    c_any: Optional[dict[str, str]] = None
+    c_any_attribute: Optional[dict[str, str]] = None
+    c_value_type: Any = None
     c_ns_prefix = None
 
     def _get_all_c_children_with_order(self):
diff --git a/src/saml2/authn.py b/src/saml2/authn.py
index dfd0a925..9a2eef51 100644
--- a/src/saml2/authn.py
+++ b/src/saml2/authn.py
@@ -269,5 +269,5 @@ try:
 
 except ImportError:
 
-    class LDAPAuthn(UserAuthnMethod):
+    class LDAPAuthn(UserAuthnMethod):  # type: ignore[no-redef]
         pass
diff --git a/src/saml2/entity.py b/src/saml2/entity.py
index 8016b481..f167a08a 100644
--- a/src/saml2/entity.py
+++ b/src/saml2/entity.py
@@ -1583,7 +1583,7 @@ class Entity(HTTPBase):
 
         typecode = _art[:2]
         if typecode != ARTIFACT_TYPECODE:
-            raise ValueError(f"Invalid artifact typecode '{typecode}' should be {ARTIFACT_TYPECODE}")
+            raise ValueError(f"Invalid artifact typecode {repr(typecode)} should be {repr(ARTIFACT_TYPECODE)}")
 
         try:
             endpoint_index = str(int(_art[2:4]))
diff --git a/src/saml2/httputil.py b/src/saml2/httputil.py
index 7217b147..3ad668b7 100644
--- a/src/saml2/httputil.py
+++ b/src/saml2/httputil.py
@@ -4,6 +4,7 @@ import hmac
 from http.cookies import SimpleCookie
 import logging
 import time
+from typing import Optional
 from urllib.parse import parse_qs
 from urllib.parse import quote
 
@@ -22,7 +23,7 @@ logger = logging.getLogger(__name__)
 
 
 class Response:
-    _template = None
+    _template: Optional[str] = None
     _status = "200 OK"
     _content_type = "text/html"
     _mako_template = None
diff --git a/src/saml2/pack.py b/src/saml2/pack.py
index 0e6923df..99c32476 100644
--- a/src/saml2/pack.py
+++ b/src/saml2/pack.py
@@ -13,7 +13,7 @@ import base64
 try:
     import html
 except Exception:
-    import cgi as html
+    import cgi as html  # type: ignore[no-redef]
 
 import logging
 from urllib.parse import urlencode
diff --git a/src/saml2/s_utils.py b/src/saml2/s_utils.py
index 2e8b4406..04a19c9e 100644
--- a/src/saml2/s_utils.py
+++ b/src/saml2/s_utils.py
@@ -343,7 +343,7 @@ def do_attribute(val, typ, key):
             friendly = ""
         if name:
             attr.name = name
-        if format:
+        if nformat:
             attr.name_format = nformat
         if friendly:
             attr.friendly_name = friendly
diff --git a/src/saml2/version.py b/src/saml2/version.py
index fa5670a9..281fab9f 100644
--- a/src/saml2/version.py
+++ b/src/saml2/version.py
@@ -1,7 +1,7 @@
 try:
     from importlib.metadata import version as _resolve_package_version
 except ImportError:
-    from importlib_metadata import version as _resolve_package_version
+    from importlib_metadata import version as _resolve_package_version  # type: ignore[no-redef]
 
 
 def _parse_version():