Use saferepr right after constructing SubtestContext

Author: nicoddemus

src/_pytest/subtests.py

@@ -11,7 +11,6 @@
 from contextlib import ExitStack
 from contextlib import nullcontext
 import dataclasses
-import pickle
 import time
 from types import TracebackType
 from typing import Any
@@ -62,17 +61,19 @@ class SubtestContext:
     msg: str | None
     kwargs: Mapping[str, Any]
 
+    def __post_init__(self) -> None:
+        # Brute-force the returned kwargs dict to be JSON serializable (pytest-dev/pytest-xdist#1273).
+        object.__setattr__(
+            self, "kwargs", {k: saferepr(v) for (k, v) in self.kwargs.items()}
+        )
+
     def _to_json(self) -> dict[str, Any]:
         result = dataclasses.asdict(self)
-        # Use protocol 0 because it is human-readable and guaranteed to be not-binary.
-        protocol = 0
-        data = pickle.dumps(result["kwargs"], protocol=protocol)
-        result["kwargs"] = data.decode("UTF-8")
         return result
 
     @classmethod
     def _from_json(cls, d: dict[str, Any]) -> Self:
-        return cls(msg=d["msg"], kwargs=pickle.loads(d["kwargs"].encode("UTF-8")))
+        return cls(msg=d["msg"], kwargs=d["kwargs"])
 
 
 @dataclasses.dataclass(init=False)

testing/test_subtests.py

@@ -5,6 +5,7 @@
 import sys
 from typing import Literal
 
+from _pytest._io.saferepr import saferepr
 from _pytest.subtests import SubtestContext
 from _pytest.subtests import SubtestReport
 import pytest
@@ -304,10 +305,10 @@ def test_foo(subtests, x):
     result = pytester.runpytest("-v")
     result.stdout.fnmatch_lines(
         [
-            "*.py::test_foo[[]0[]] SUBFAILED[[]custom[]] (i=1) *[[] 50%[]]",
-            "*.py::test_foo[[]0[]] FAILED                      *[[] 50%[]]",
-            "*.py::test_foo[[]1[]] SUBFAILED[[]custom[]] (i=1) *[[]100%[]]",
-            "*.py::test_foo[[]1[]] FAILED                      *[[]100%[]]",
+            "*.py::test_foo[[]0[]] SUBFAILED[[]custom[]] (i='1') *[[] 50%[]]",
+            "*.py::test_foo[[]0[]] FAILED                        *[[] 50%[]]",
+            "*.py::test_foo[[]1[]] SUBFAILED[[]custom[]] (i='1') *[[]100%[]]",
+            "*.py::test_foo[[]1[]] FAILED                        *[[]100%[]]",
             "contains 1 failed subtest",
             "* 4 failed, 4 subtests passed in *",
         ]
@@ -322,10 +323,10 @@ def test_foo(subtests, x):
     result = pytester.runpytest("-v")
     result.stdout.fnmatch_lines(
         [
-            "*.py::test_foo[[]0[]] SUBFAILED[[]custom[]] (i=1) *[[] 50%[]]",
-            "*.py::test_foo[[]0[]] FAILED                      *[[] 50%[]]",
-            "*.py::test_foo[[]1[]] SUBFAILED[[]custom[]] (i=1) *[[]100%[]]",
-            "*.py::test_foo[[]1[]] FAILED                      *[[]100%[]]",
+            "*.py::test_foo[[]0[]] SUBFAILED[[]custom[]] (i='1') *[[] 50%[]]",
+            "*.py::test_foo[[]0[]] FAILED                        *[[] 50%[]]",
+            "*.py::test_foo[[]1[]] SUBFAILED[[]custom[]] (i='1') *[[]100%[]]",
+            "*.py::test_foo[[]1[]] FAILED                        *[[]100%[]]",
             "contains 1 failed subtest",
             "* 4 failed in *",
         ]
@@ -652,12 +653,12 @@ def test_capturing(self, pytester: pytest.Pytester, mode: str) -> None:
         result = pytester.runpytest(f"--capture={mode}")
         result.stdout.fnmatch_lines(
             [
-                "*__ test (i='A') __*",
+                "*__ test (i=\"'A'\") __*",
                 "*Captured stdout call*",
                 "hello stdout A",
                 "*Captured stderr call*",
                 "hello stderr A",
-                "*__ test (i='B') __*",
+                "*__ test (i=\"'B'\") __*",
                 "*Captured stdout call*",
                 "hello stdout B",
                 "*Captured stderr call*",
@@ -678,8 +679,8 @@ def test_no_capture(self, pytester: pytest.Pytester) -> None:
                 "hello stdout A",
                 "uhello stdout B",
                 "uend test",
-                "*__ test (i='A') __*",
-                "*__ test (i='B') __*",
+                "*__ test (i=\"'A'\") __*",
+                "*__ test (i=\"'B'\") __*",
                 "*__ test __*",
             ]
         )
@@ -986,7 +987,7 @@ def test_serialization() -> None:
     new_report = pytest_report_from_serializable(data)
     assert new_report is not None
     assert new_report.context == SubtestContext(
-        msg="custom message", kwargs=dict(i=10, a=MyEnum.A)
+        msg="custom message", kwargs=dict(i=saferepr(10), a=saferepr(MyEnum.A))
     )