don't crash if exceptiongroup has only hidden tb frames

changelog/13734.bugfix.rst

@@ -0,0 +1 @@
+Fixed crash when a test raises an exceptiongroup with ``__tracebackhide__ = True``.

src/_pytest/_code/code.py

@@ -1193,9 +1193,15 @@ def repr_excinfo(self, excinfo: ExceptionInfo[BaseException]) -> ExceptionChainR
                         format_exception(
                             type(excinfo.value),
                             excinfo.value,
-                            traceback[0]._rawentry,
+                            traceback[0]._rawentry if traceback else None,
                         )
                     )
+                    if not traceback:
+                        reprtraceback.extraline = (
+                            "All traceback entries are hidden. "
+                            "Pass `--full-trace` to see hidden and internal frames."
+                        )
+
                 else:
                     reprtraceback = self.repr_traceback(excinfo_)
                 reprcrash = excinfo_._getreprcrash()

testing/code/test_excinfo.py

@@ -1897,19 +1897,23 @@ def test_nested_multiple() -> None:
 
 
 @pytest.mark.parametrize("tbstyle", ("long", "short", "auto", "line", "native"))
-def test_all_entries_hidden(pytester: Pytester, tbstyle: str) -> None:
+@pytest.mark.parametrize("group", (True, False), ids=("group", "bare"))
+def test_all_entries_hidden(pytester: Pytester, tbstyle: str, group: bool) -> None:
     """Regression test for #10903."""
     pytester.makepyfile(
-        """
+        f"""
+        import sys
+        if sys.version_info < (3, 11):
+            from exceptiongroup import ExceptionGroup
         def test():
             __tracebackhide__ = True
-            1 / 0
+            raise {'ExceptionGroup("", [ValueError("bar")])' if group else 'ValueError("bar")'}
     """
     )
     result = pytester.runpytest("--tb", tbstyle)
     assert result.ret == 1
     if tbstyle != "line":
-        result.stdout.fnmatch_lines(["*ZeroDivisionError: division by zero"])
+        result.stdout.fnmatch_lines(["*ValueError: bar"])
     if tbstyle not in ("line", "native"):
         result.stdout.fnmatch_lines(["All traceback entries are hidden.*"])