[tests] refactor python tests

* try to adapt a more modern python style
* add flake8 linting and mypy type checking
  * add many type hints
  * dataclasses
  * various refactorings to make proper type hints possible
* use f-strings for formatting instead of `%` and `.format`
* get rid of `Env` global; pass it explicitly or use a ContextVar
* use metaclass to automatically register test cases

Change-Id: I19d6223157b769cb6491c032d3ec9eb2cd70ef44

Author: stbuehler

.flake8

@@ -0,0 +1,8 @@
+[flake8]
+# E266 too many leading '#' for block comment [ I like marking disabled code blocks with '### ' ]
+# E402 module level import not at top of file [ usually on purpose. might use individual overrides instead? ]
+# E713 test for membership should be ‘not in’ [ disagree: want `not a in x` ]
+# E714 test for object identity should be 'is not' [ disagree: want `not a is x` ]
+# W503 line break before binary operator [ gotta pick one way ]
+extend-ignore = E266,E402,E713,E714,W503
+max-line-length = 120

.gitignore

@@ -15,3 +15,5 @@ install-sh
 ltmain.sh
 missing
 CMakeLists.txt.user
+.vscode
+.mypy_cache

pyproject.toml

@@ -0,0 +1,13 @@
+[tool.pyright]
+include = ["tests"]
+
+[[tool.pyright.executionEnvironments]]
+root = "tests"
+
+[tool.mypy]
+warn_unused_configs = true
+mypy_path = "tests"
+files = "tests"
+implicit_reexport = false
+show_error_codes = true
+follow_imports = "silent"

tests/CONTRIBUTE.md

@@ -0,0 +1 @@
+Please run `mypy` and `flake8 tests` in project root and fix errors/lints.