Implement unpacking nested pytest.param objects

- Merge nested ids (if parent pytest.param don't have id)
- Merge nested marks with parent

AUTHORS

@@ -334,6 +334,7 @@ Virgil Dupras
 Vitaly Lashmanov
 Vlad Dragos
 Vlad Radziuk
+Vladimir Gorkavenko
 Vladyslav Rachek
 Volodymyr Piskun
 Wei Lin

changelog/9074.improvement.rst

@@ -0,0 +1,17 @@
+Now ``pytest`` do unpack nested ``pytest.param`` values and merge their ids and marks.
+If parent ``pytest.param`` has an id - it rewrites nested ids.
+For example, now such a construction is possible::
+
+        @pytest.mark.parametrize(
+            "a,b,c", [
+                pytest.param(
+                    pytest.param(1, id="one", marks=pytest.mark.one),
+                    pytest.param(2, id="two", marks=pytest.mark.two),
+                    pytest.param(3, id="three", marks=pytest.mark.three),
+                    marks=pytest.mark.full
+                )
+            ]
+        )
+
+
+Earlier in this case the values ``a, b, c`` in test are a ``ParameterSet`` objects

src/_pytest/python.py

@@ -1126,9 +1126,21 @@ class Metafunc:
         # Create the new calls: if we are parametrize() multiple times (by applying the decorator
         # more than once) then we accumulate those calls generating the cartesian product
         # of all calls.
+        # If we parametrize the test using values that contained nested pytest.param objects,
+        # then we unpack them values and merge marks.
         newcalls = []
         for callspec in self._calls or [CallSpec2()]:
             for param_index, (param_id, param_set) in enumerate(zip(ids, parameters)):
+                normalized_values = []
+                merged_marks = list(param_set.marks) if param_set.marks else []
+                for param_value in param_set.values:
+                    if not isinstance(param_value, ParameterSet):
+                        normalized_values.append(param_value)
+                    else:
+                        normalized_values.append(*param_value.values)
+                        if param_value.marks:
+                            merged_marks.append(*param_value.marks)
+                param_set = ParameterSet(values=tuple(normalized_values), marks=merged_marks, id=None)
                 newcallspec = callspec.setmulti(
                     valtypes=arg_values_types,
                     argnames=argnames,
@@ -1385,10 +1397,15 @@ def _idvalset(
         return parameterset.id
     id = None if ids is None or idx >= len(ids) else ids[idx]
     if id is None:
-        this_id = [
-            _idval(val, argname, idx, idfn, nodeid=nodeid, config=config)
-            for val, argname in zip(parameterset.values, argnames)
-        ]
+        this_id = []
+        for val, argname in zip(parameterset.values, argnames):
+            to_get_idval = val
+            if isinstance(val, ParameterSet):
+                if val.id:
+                    this_id.append(val.id)
+                    continue
+                to_get_idval = (val.values[0] if len(val.values) == 1 else val.values)
+            this_id.append(_idval(to_get_idval, argname, idx, idfn, nodeid=nodeid, config=config))
         return "-".join(this_id)
     else:
         return _ascii_escaped_by_config(id, config)

testing/test_mark.py

@@ -1,6 +1,6 @@
 import os
 import sys
-from typing import List
+from typing import List, NamedTuple, Tuple, Any
 from typing import Optional
 from unittest import mock
 
@@ -344,6 +344,61 @@ def test_parametrize_with_module(pytester: Pytester) -> None:
     assert passed[0].nodeid.split("::")[-1] == expected_id
 
 
+@pytest.fixture()
+def pytester_internal_test_values():
+    pytest.internal_test_values = []  # type: ignore[attr-defined]
+    yield pytest.internal_test_values  # type: ignore[attr-defined]
+    del pytest.internal_test_values  # type: ignore[attr-defined]
+
+
+def test_parametrize_with_nested_paramsets(pytester: Pytester, pytester_internal_test_values: List[Any]) -> None:
+    """Test parametrize with nested pytest.param objects in value"""
+    case = NamedTuple(
+        "case",
+        [
+            ("expected_test_id", str),
+            ("expected_value", Tuple[Any, ...]),
+            ("expected_marks", Tuple[str, ...]),
+        ],
+    )
+    cases = (
+        case("1-nested_2-3", (1, 2, 3), ("parametrize",)),
+        case("one_two_three", (1, 2, 3), ("parametrize",)),
+        case("1-nested_2-tuple_value", (1, 2, (3, 3)), ("parametrize",)),
+        case("1-2-3", (1, 2, 3), ("parametrize", "a", "b", "c", "all",)),
+    )
+    pytester.makepyfile(
+        """
+        import pytest
+        @pytest.mark.parametrize(
+            "a, b, c", 
+            [
+                (1, pytest.param(2, id="nested_2"), pytest.param(3)),
+                pytest.param(1, pytest.param(2, id="nested_2"), pytest.param(3), id="one_two_three"),
+                (1, pytest.param(2, id="nested_2"), pytest.param((3, 3), id="tuple_value")),
+                pytest.param(
+                    pytest.param(1, marks=pytest.mark.a),
+                    pytest.param(2, marks=pytest.mark.b),
+                    pytest.param(3, marks=pytest.mark.c),
+                    marks=pytest.mark.all
+                ),
+            ]
+        )
+        def test_func(a, b, c):
+            pytest.internal_test_values.append((a, b, c))
+    """
+    )
+    rec = pytester.inline_run()
+    items = [x.item for x in rec.getcalls("pytest_itemcollected")]
+    passed, _, _ = rec.listoutcomes()
+    for i, case_ in enumerate(cases):
+        markers = {m.name for m in (items[i].iter_markers() or ())}
+        expected_id = "test_func[" + case_.expected_test_id + "]"
+        assert markers == set(case_.expected_marks)
+        assert passed[i].nodeid.split("::")[-1] == expected_id
+        assert pytester_internal_test_values[i] == case_.expected_value
+
+
 @pytest.mark.parametrize(
     ("expr", "expected_error"),
     [