feat(tests): add subtests to framework tests as an example

Added a new test class `TestSubtests` to verify outcomes using subtests.

framework_tests/test_subtests.py

@@ -0,0 +1,26 @@
+import pytest
+import pytest_subtests
+
+
+class TestSubtests:
+    def test_outcomes(
+        self,
+        subtests: pytest_subtests.SubTests,
+    ):
+        xfail_msgs = []
+
+        # In subtest, don't return any other outcome than success or failure.
+        # Allure doesn't work well with subtests. It will use outcome of the first non-successful
+        # subtest as the overall test outcome.
+        # Therefore skiped / xfailed subtests could mask subtest failures. As a workaround,
+        # record the outcome of the subtest and use it as the outcome of the main test.
+        def _subtest(num: int) -> None:
+            if num > 200:
+                xfail_msgs.append(f"{num} > 200")
+
+        for n in (100, 200, 300, 500):
+            with subtests.test(msg="check num", num=n):
+                _subtest(n)
+
+        if xfail_msgs:
+            pytest.xfail("; ".join(xfail_msgs))