main: wrap_session: handle exit.Exception with notify_exception

Fixes #6257.
Via blueyed#132.

Author: blueyed

changelog/6257.improvement.rst

@@ -0,0 +1 @@
+Handle `exit.Exception` raised in `notify_exception` (via `pytest_internalerror`), e.g. when quitting pdb from post mortem.

src/_pytest/main.py

@@ -212,11 +212,17 @@ def wrap_session(config, doit):
             config.hook.pytest_keyboard_interrupt(excinfo=excinfo)
             session.exitstatus = exitstatus
         except:  # noqa
-            excinfo = _pytest._code.ExceptionInfo.from_current()
-            config.notify_exception(excinfo, config.option)
             session.exitstatus = ExitCode.INTERNAL_ERROR
-            if excinfo.errisinstance(SystemExit):
-                sys.stderr.write("mainloop: caught unexpected SystemExit!\n")
+            excinfo = _pytest._code.ExceptionInfo.from_current()
+            try:
+                config.notify_exception(excinfo, config.option)
+            except exit.Exception as exc:
+                if exc.returncode is not None:
+                    session.exitstatus = exc.returncode
+                sys.stderr.write("{}: {}\n".format(type(exc).__name__, exc))
+            else:
+                if excinfo.errisinstance(SystemExit):
+                    sys.stderr.write("mainloop: caught unexpected SystemExit!\n")
 
     finally:
         excinfo = None  # Explicitly break reference cycle.

testing/test_main.py

@@ -0,0 +1,32 @@
+import pytest
+from _pytest.main import ExitCode
+
+
+@pytest.mark.parametrize("ret_exc", ((None, ValueError), (42, SystemExit)))
+def test_wrap_session_notify_exception(ret_exc, testdir):
+    returncode, exc = ret_exc
+    c1 = testdir.makeconftest(
+        """
+        import pytest
+
+        def pytest_sessionstart():
+            raise {exc}("boom")
+
+        def pytest_internalerror(excrepr, excinfo):
+            pytest.exit("exiting after %s..." % excinfo.typename, returncode={returncode!r})
+    """.format(
+            returncode=returncode, exc=exc.__name__
+        )
+    )
+    result = testdir.runpytest()
+    if returncode:
+        assert result.ret == returncode
+    else:
+        assert result.ret == ExitCode.INTERNAL_ERROR
+    result.stdout.lines[0] == "INTERNALERROR> Traceback (most recent call last):"
+    result.stdout.lines[-3:] == [
+        'INTERNALERROR>   File "{}", line 2, in pytest_sessionstart'.format(c1),
+        "INTERNALERROR>     raise ValueError",
+        "INTERNALERROR> ValueError: boom",
+    ]
+    assert result.stderr.lines == ["Exit: exiting after {}...".format(exc.__name__)]