fallback to native traceback when handling ExceptionGroup (take 2) [SQUASH] (#10209)

* Squashed commit of the following:

commit 41d339c46763bbe26123e1e6504b6e32290e33e1
Author: Cheukting <cheukting.ho@gmail.com>
Date:   Thu Jun 23 17:01:04 2022 +0800

    test in all py versions

commit b3572a5a12672228c3276fc8c8e05980dfb7888a
Author: Cheukting <cheukting.ho@gmail.com>
Date:   Thu Jun 23 16:41:06 2022 +0800

    add test

commit 7166a2a51e4f99046b028b663c193d8b558c7fd4
Author: Cheukting <cheukting.ho@gmail.com>
Date:   Thu Jun 23 16:00:07 2022 +0800

    update changelog

commit b958c73d489157f0c0d4e46425083a5e2e2bc851
Author: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date:   Thu Jun 23 07:50:52 2022 +0000

    [pre-commit.ci] auto fixes from pre-commit.com hooks

    for more information, see https://pre-commit.ci

commit ea7f376c6ca37c40c83df0e4a1cfaaedb34bae91
Author: Cheukting <cheukting.ho@gmail.com>
Date:   Thu Jun 23 15:48:21 2022 +0800

    Fix MyPy

commit 97469beb1da40257e9a061a5e19548546c9312c4
Author: Cheukting <cheukting.ho@gmail.com>
Date:   Thu Jun 23 15:03:48 2022 +0800

    fix if ExceptionGroup not exist

commit 84e553642cd69b4d499231d733df91ebfa84c7ad
Author: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date:   Thu Jun 23 03:43:27 2022 +0000

    [pre-commit.ci] auto fixes from pre-commit.com hooks

    for more information, see https://pre-commit.ci

commit 76bbef449b88bbd74fb5cca3b5293337a624ef03
Author: Cheukting <cheukting.ho@gmail.com>
Date:   Thu Jun 23 11:40:41 2022 +0800

    adding changelog

commit db82bebc5a4969e2083adcd97bdfd2a63bb17d98
Author: Cheukting <cheukting.ho@gmail.com>
Date:   Thu Jun 23 11:33:10 2022 +0800

    fall back to native when handeling to exception groups

* Typed ExceptionGroupTypes and changed to BaseExceptionGroup, fixed exceptionchain (excinfo->excinfo_, set reprcrash. Extended tests, though they're wip.

* added exceptiongroup to pre-commit-config, moved away from tuple to directly defining BaseExceptionGroup, added block comment, added match line for inner exception, changked mark.skipif to importorskip to not need top-level import, changed tox.ini a bit - only uncovered should now be py37 without exceptiongroup, due to hypothesis

* added py311-exceptiongroup to github CI, exceptiongroup is now a hard dependency on py<3.11, renamed bad variable names

* added use_coverage to ubuntu-py311

* import BaseExceptionGroup with explicit version check instead of try/catch

* removed from CI, added comments to tox and pre-commit

.github/workflows/test.yml

@@ -114,6 +114,7 @@ jobs:
             python: "3.11-dev"
             os: ubuntu-latest
             tox_env: "py311"
+            use_coverage: true
           - name: "ubuntu-pypy3"
             python: "pypy-3.7"
             os: ubuntu-latest

.pre-commit-config.yaml

@@ -68,6 +68,9 @@ repos:
           - packaging
           - tomli
           - types-pkg_resources
+            # for mypy running on python>=3.11 since exceptiongroup is only a dependency
+            # on <3.11
+          - exceptiongroup>=1.0.0rc8
 -   repo: local
     hooks:
     -   id: rst

AUTHORS

@@ -168,6 +168,7 @@ Jeff Rackauckas
 Jeff Widman
 Jenni Rinker
 John Eddie Ayson
+John Litborn
 John Towler
 Jon Parise
 Jon Sonesen

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``.

setup.cfg

@@ -47,6 +47,7 @@ install_requires =
     pluggy>=0.12,<2.0
     py>=1.8.2
     colorama;sys_platform=="win32"
+    exceptiongroup>=1.0.0rc8;python_version<"3.11"
     importlib-metadata>=0.12;python_version<"3.8"
     tomli>=1.0.0;python_version<"3.11"
 python_requires = >=3.7

src/_pytest/_code/code.py

@@ -56,6 +56,9 @@ if TYPE_CHECKING:
 
     _TracebackStyle = Literal["long", "short", "line", "no", "native", "value", "auto"]
 
+if sys.version_info[:2] < (3, 11):
+    from exceptiongroup import BaseExceptionGroup
+
 
 class Code:
     """Wrapper around Python code objects."""
@@ -924,7 +927,21 @@ class FormattedExcinfo:
         while e is not None and id(e) not in seen:
             seen.add(id(e))
             if excinfo_:
-                reprtraceback = self.repr_traceback(excinfo_)
+                # 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
+                if isinstance(e, BaseExceptionGroup):
+                    reprtraceback: Union[
+                        ReprTracebackNative, ReprTraceback
+                    ] = ReprTracebackNative(
+                        traceback.format_exception(
+                            type(excinfo_.value),
+                            excinfo_.value,
+                            excinfo_.traceback[0]._rawentry,
+                        )
+                    )
+                else:
+                    reprtraceback = self.repr_traceback(excinfo_)
                 reprcrash: Optional[ReprFileLocation] = (
                     excinfo_._getreprcrash() if self.style != "value" else None
                 )

testing/code/test_excinfo.py

@@ -1470,3 +1470,90 @@ def test_no_recursion_index_on_recursion_error():
     with pytest.raises(RuntimeError) as excinfo:
         RecursionDepthError().trigger
     assert "maximum recursion" in str(excinfo.getrepr())
+
+
+def _exceptiongroup_common(
+    pytester: Pytester,
+    outer_chain: str,
+    inner_chain: str,
+    native: bool,
+) -> None:
+    pre_raise = "exceptiongroup." if not native else ""
+    pre_catch = pre_raise if sys.version_info < (3, 11) else ""
+    filestr = f"""
+    {"import exceptiongroup" if not native else ""}
+    import pytest
+
+    def f(): raise ValueError("From f()")
+    def g(): raise BaseException("From g()")
+
+    def inner(inner_chain):
+        excs = []
+        for callback in [f, g]:
+            try:
+                callback()
+            except BaseException as err:
+                excs.append(err)
+        if excs:
+            if inner_chain == "none":
+                raise {pre_raise}BaseExceptionGroup("Oops", excs)
+            try:
+                raise SyntaxError()
+            except SyntaxError as e:
+                if inner_chain == "from":
+                    raise {pre_raise}BaseExceptionGroup("Oops", excs) from e
+                else:
+                    raise {pre_raise}BaseExceptionGroup("Oops", excs)
+
+    def outer(outer_chain, inner_chain):
+        try:
+            inner(inner_chain)
+        except {pre_catch}BaseExceptionGroup as e:
+            if outer_chain == "none":
+                raise
+            if outer_chain == "from":
+                raise IndexError() from e
+            else:
+                raise IndexError()
+
+
+    def test():
+        outer("{outer_chain}", "{inner_chain}")
+    """
+    pytester.makepyfile(test_excgroup=filestr)
+    result = pytester.runpytest()
+    match_lines = []
+    if inner_chain in ("another", "from"):
+        match_lines.append(r"SyntaxError: <no detail available>")
+
+    match_lines += [
+        r"  + Exception Group Traceback (most recent call last):",
+        rf"  \| {pre_catch}BaseExceptionGroup: Oops \(2 sub-exceptions\)",
+        r"    \| ValueError: From f\(\)",
+        r"    \| BaseException: From g\(\)",
+        r"=* short test summary info =*",
+    ]
+    if outer_chain in ("another", "from"):
+        match_lines.append(r"FAILED test_excgroup.py::test - IndexError")
+    else:
+        match_lines.append(
+            rf"FAILED test_excgroup.py::test - {pre_catch}BaseExceptionGroup: Oops \(2.*"
+        )
+    result.stdout.re_match_lines(match_lines)
+
+
+@pytest.mark.skipif(
+    sys.version_info < (3, 11), reason="Native ExceptionGroup not implemented"
+)
+@pytest.mark.parametrize("outer_chain", ["none", "from", "another"])
+@pytest.mark.parametrize("inner_chain", ["none", "from", "another"])
+def test_native_exceptiongroup(pytester: Pytester, outer_chain, inner_chain) -> None:
+    _exceptiongroup_common(pytester, outer_chain, inner_chain, native=True)
+
+
+@pytest.mark.parametrize("outer_chain", ["none", "from", "another"])
+@pytest.mark.parametrize("inner_chain", ["none", "from", "another"])
+def test_exceptiongroup(pytester: Pytester, outer_chain, inner_chain) -> None:
+    # with py>=3.11 does not depend on exceptiongroup, though there is a toxenv for it
+    pytest.importorskip("exceptiongroup")
+    _exceptiongroup_common(pytester, outer_chain, inner_chain, native=False)

tox.ini

@@ -17,6 +17,10 @@ envlist =
     docs
     docs-checklinks
 
+    # checks that 3.11 native ExceptionGroup works with exceptiongroup
+    # not included in CI.
+    py311-exceptiongroup
+
 
 
 [testenv]
@@ -46,6 +50,7 @@ setenv =
 extras = testing
 deps =
     doctesting: PyYAML
+    exceptiongroup: exceptiongroup>=1.0.0rc8
     numpy: numpy>=1.19.4
     pexpect: pexpect>=4.8.0
     pluggymain: pluggy @ git+https://github.com/pytest-dev/pluggy.git