unittest: handle outcomes.Exit

This is required for pytest to stop when using "quit" in pdb, and should
get honored/handled in general.

src/_pytest/unittest.py

@@ -6,6 +6,7 @@ import _pytest._code
 import pytest
 from _pytest.compat import getimfunc
 from _pytest.config import hookimpl
+from _pytest.outcomes import exit
 from _pytest.outcomes import fail
 from _pytest.outcomes import skip
 from _pytest.outcomes import xfail
@@ -153,6 +154,11 @@ class TestCaseFunction(Function):
         self.__dict__.setdefault("_excinfo", []).append(excinfo)
 
     def addError(self, testcase, rawexcinfo):
+        try:
+            if isinstance(rawexcinfo[1], exit.Exception):
+                exit(rawexcinfo[1].msg)
+        except TypeError:
+            pass
         self._addexcinfo(rawexcinfo)
 
     def addFailure(self, testcase, rawexcinfo):

testing/test_unittest.py

@@ -1050,3 +1050,39 @@ def test_setup_inheritance_skipping(testdir, test_name, expected_outcome):
     testdir.copy_example("unittest/{}".format(test_name))
     result = testdir.runpytest()
     result.stdout.fnmatch_lines(["* {} in *".format(expected_outcome)])
+
+
+def test_BdbQuit(testdir):
+    testdir.makepyfile(
+        test_foo="""
+        import unittest
+
+        class MyTestCase(unittest.TestCase):
+            def test_bdbquit(self):
+                import bdb
+                raise bdb.BdbQuit()
+
+            def test_should_not_run(self):
+                pass
+    """
+    )
+    reprec = testdir.inline_run()
+    reprec.assertoutcome(failed=1, passed=1)
+
+
+def test_exit_outcome(testdir):
+    testdir.makepyfile(
+        test_foo="""
+        import pytest
+        import unittest
+
+        class MyTestCase(unittest.TestCase):
+            def test_exit_outcome(self):
+                pytest.exit("pytest_exit")
+
+            def test_should_not_run(self):
+                pass
+    """
+    )
+    reprec = testdir.inline_run()
+    reprec.assertoutcome()