move logic to ExceptionInfo

Author: jakkdl

src/_pytest/_code/code.py

@@ -589,6 +589,31 @@ def exconly(self, tryshort: bool = False) -> str:
         representation is returned (so 'AssertionError: ' is removed from
         the beginning).
         """
+
+        def _get_single_subexc(
+            eg: BaseExceptionGroup[BaseException],
+        ) -> BaseException | None:
+            res: BaseException | None = None
+            for subexc in eg.exceptions:
+                if res is not None:
+                    return None
+
+                if isinstance(subexc, BaseExceptionGroup):
+                    res = _get_single_subexc(subexc)
+                    if res is None:
+                        # there were multiple exceptions in the subgroup
+                        return None
+                else:
+                    res = subexc
+            return res
+
+        if (
+            tryshort
+            and isinstance(self.value, BaseExceptionGroup)
+            and (subexc := _get_single_subexc(self.value)) is not None
+        ):
+            return f"[in {type(self.value).__name__}] {subexc!r}"
+
         lines = format_exception_only(self.type, self.value)
         text = "".join(lines)
         text = text.rstrip()
@@ -1033,24 +1058,6 @@ def _truncate_recursive_traceback(
 
     def repr_excinfo(self, excinfo: ExceptionInfo[BaseException]) -> ExceptionChainRepr:
         repr_chain: list[tuple[ReprTraceback, ReprFileLocation | None, str | None]] = []
-
-        def _get_single_subexc(
-            eg: BaseExceptionGroup[BaseException],
-        ) -> BaseException | None:
-            res: BaseException | None = None
-            for subexc in eg.exceptions:
-                if res is not None:
-                    return None
-
-                if isinstance(subexc, BaseExceptionGroup):
-                    res = _get_single_subexc(subexc)
-                    if res is None:
-                        # there were multiple exceptions in the subgroup
-                        return None
-                else:
-                    res = subexc
-            return res
-
         e: BaseException | None = excinfo.value
         excinfo_: ExceptionInfo[BaseException] | None = excinfo
         descr = None
@@ -1059,7 +1066,6 @@ def _get_single_subexc(
             seen.add(id(e))
 
             if excinfo_:
-                reprcrash = excinfo_._getreprcrash()
                 # Fall back to native traceback as a temporary workaround until
                 # full support for exception groups added to ExceptionInfo.
                 # See https://github.com/pytest-dev/pytest/issues/9159
@@ -1073,13 +1079,9 @@ def _get_single_subexc(
                             )
                         )
                     )
-                    if (
-                        reprcrash is not None
-                        and (subexc := _get_single_subexc(e)) is not None
-                    ):
-                        reprcrash.message = f"[in {type(e).__name__}] {subexc!r}"
                 else:
                     reprtraceback = self.repr_traceback(excinfo_)
+                reprcrash = excinfo_._getreprcrash()
             else:
                 # Fallback to native repr if the exception doesn't have a traceback:
                 # ExceptionInfo objects require a full traceback to work.