fall back to native when handeling to exception groups

changelog/9159.bugfix.rst

@@ -0,0 +1 @@
+Showing inner exceptions by forcing native display in ``ExceptionGroups`` even when using display options other than ``--tb=native``. A temporary step before full implementation of pytest-native display for inner exceptions in ``ExceptionGroups``.

src/_pytest/_code/code.py

@@ -56,6 +56,18 @@
 
     _TracebackStyle = Literal["long", "short", "line", "no", "native", "value", "auto"]
 
+ExceptionGroupTypes: tuple = ()  # type: ignore
+try:
+    ExceptionGroupTypes += (ExceptionGroup,)  # type: ignore
+except NameError:
+    pass  # Is missing for `python<3.10`
+try:
+    import exceptiongroup
+
+    ExceptionGroupTypes += (exceptiongroup.ExceptionGroup,)
+except ModuleNotFoundError:
+    pass  # No backport is installed
+
 
 class Code:
     """Wrapper around Python code objects."""
@@ -923,11 +935,20 @@ def repr_excinfo(
         seen: Set[int] = set()
         while e is not None and id(e) not in seen:
             seen.add(id(e))
-            if excinfo_:
-                reprtraceback = self.repr_traceback(excinfo_)
-                reprcrash: Optional[ReprFileLocation] = (
-                    excinfo_._getreprcrash() if self.style != "value" else None
+            if isinstance(e, ExceptionGroupTypes):
+                reprtraceback: Union[
+                    ReprTracebackNative, ReprTraceback
+                ] = ReprTracebackNative(
+                    traceback.format_exception(
+                        type(excinfo.value),
+                        excinfo.value,
+                        excinfo.traceback[0]._rawentry,
+                    )
                 )
+                reprcrash: Optional[ReprFileLocation] = None
+            elif excinfo_:
+                reprtraceback = self.repr_traceback(excinfo_)
+                reprcrash = excinfo_._getreprcrash() if self.style != "value" else None
             else:
                 # Fallback to native repr if the exception doesn't have a traceback:
                 # ExceptionInfo objects require a full traceback to work.

testing/code/test_excinfo.py

@@ -1470,3 +1470,34 @@ def __getattr__(self, attr):
     with pytest.raises(RuntimeError) as excinfo:
         RecursionDepthError().trigger
     assert "maximum recursion" in str(excinfo.getrepr())
+
+
+def test_exceptiongroup(pytester: Pytester) -> None:
+    pytester.makepyfile(
+        """
+        def f(): raise ValueError("From f()")
+        def g(): raise RuntimeError("From g()")
+
+        def main():
+            excs = []
+            for callback in [f, g]:
+                try:
+                    callback()
+                except Exception as err:
+                    excs.append(err)
+            if excs:
+                raise ExceptionGroup("Oops", excs)
+
+        def test():
+            main()
+    """
+    )
+    result = pytester.runpytest()
+    assert result.ret != 0
+
+    match = [
+        r"  | ExceptionGroup: Oops (2 sub-exceptions)",
+        r"    | ValueError: From f()",
+        r"    | RuntimeError: From g()",
+    ]
+    result.stdout.re_match_lines(match)

tox.ini

@@ -46,6 +46,7 @@ setenv =
 extras = testing
 deps =
     doctesting: PyYAML
+    exceptiongroup: exceptiongroup>=1.0.0
     numpy: numpy>=1.19.4
     pexpect: pexpect>=4.8.0
     pluggymain: pluggy @ git+https://github.com/pytest-dev/pluggy.git