Enable mypy.

.mypy.ini

@@ -0,0 +1,23 @@
+# Copyright (c) Ansible Project
+# GNU General Public License v3.0+ (see LICENSES/GPL-3.0-or-later.txt or https://www.gnu.org/licenses/gpl-3.0.txt)
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+[mypy]
+check_untyped_defs = True
+disallow_untyped_defs = True
+
+# strict = True -- only try to enable once everything (including dependencies!) is typed
+strict_equality = True
+strict_bytes = True
+
+warn_redundant_casts = True
+# warn_return_any = True
+warn_unreachable = True
+
+[mypy-ansible.*]
+# ansible-core has partial typing information
+follow_untyped_imports = True
+
+[mypy-ansible_collections.community.internal_test_tools.*]
+# community.internal_test_tools has no typing information
+ignore_missing_imports = True

antsibull-nox.toml

@@ -25,7 +25,9 @@ run_yamllint = true
 yamllint_config = ".yamllint"
 yamllint_config_plugins = ".yamllint-docs"
 yamllint_config_plugins_examples = ".yamllint-examples"
-run_mypy = false
+run_mypy = true
+mypy_ansible_core_package = "ansible-core>=2.19.0"
+mypy_config = ".mypy.ini"
 
 [sessions.docs_check]
 validate_collection_refs="all"