Bump the minimum required python version to 3.10

Drop support of EoL python versions for running system tests. The
maintenance cost of supporting end of life ecosystem, especially Python
3.6 on EL8 and the related outdated packages (pytest, dnspython, ...),
has become unreasonable.

bin/tests/system/README.md

@@ -46,16 +46,11 @@ nameserver and is listed in the hints file of the others.
 
 To run system tests, make sure you have the following dependencies installed:
 
-- python3
-- pytest
+- python3 (3.10 and newer)
 - perl
-- dnspython
-- pytest-xdist (for parallel execution)
-- python-jinja2
 
-Individual system tests might also require additional dependencies. If those
-are missing, the affected tests will be skipped and should produce a message
-specifying what additional prerequisites they expect.
+List of required python packages and their versions can be found in
+requirements.txt (can be installed with `pip3 install -r requirements.txt`).
 
 ### Network Setup
 

bin/tests/system/conftest.py

@@ -17,6 +17,7 @@ import shutil
 import subprocess
 import tempfile
 import time
+import sys
 
 import pytest
 
@@ -29,6 +30,8 @@ from isctest.vars.build import SYSTEM_TEST_DIR_GIT_PATH
 # Silence warnings caused by passing a pytest fixture to another fixture.
 # pylint: disable=redefined-outer-name
 
+if sys.version_info[1] < 10:
+    raise RuntimeError("Python 3.10 or newer is required to run system tests.")
 
 isctest.log.init_conftest_logger()
 isctest.log.avoid_duplicated_logs()
@@ -359,12 +362,6 @@ def system_test_dir(request, system_test_name, expected_artifacts):
         assert all(res.outcome == "passed" for res in test_results.values())
         return "passed"
 
-    def unlink(path):
-        try:
-            path.unlink()  # missing_ok=True isn't available on Python 3.6
-        except FileNotFoundError:
-            pass
-
     def check_artifacts(source_dir, run_dir):
         def check_artifacts_recursive(dcmp):
             def artifact_expected(path, expected):
@@ -409,7 +406,7 @@ def system_test_dir(request, system_test_name, expected_artifacts):
     # Create a convenience symlink with a stable and predictable name
     module_name = SYMLINK_REPLACEMENT_RE.sub(r"\1", str(request.node.path))
     symlink_dst = system_test_root / module_name
-    unlink(symlink_dst)
+    symlink_dst.unlink(missing_ok=True)
     symlink_dst.symlink_to(os.path.relpath(testdir, start=system_test_root))
 
     isctest.log.init_module_logger(system_test_name, testdir)
@@ -461,7 +458,7 @@ def system_test_dir(request, system_test_name, expected_artifacts):
         isctest.log.deinit_module_logger()
         if not keep:
             shutil.rmtree(testdir)
-            unlink(symlink_dst)
+            symlink_dst.unlink(missing_ok=True)
 
 
 @pytest.fixture(scope="module")