Fix #841: BreakOnSystemExitZero debug option is not respected

src/ptvsd/wrapper.py

@@ -819,6 +819,7 @@ def bool_parser(str):
 DEBUG_OPTIONS_PARSER = {
     'WAIT_ON_ABNORMAL_EXIT': bool_parser,
     'WAIT_ON_NORMAL_EXIT': bool_parser,
+    'BREAK_SYSTEMEXIT_ZERO': bool_parser,
     'REDIRECT_OUTPUT': bool_parser,
     'VERSION': unquote,
     'INTERPRETER_OPTIONS': unquote,
@@ -837,6 +838,7 @@ DEBUG_OPTIONS_BY_FLAG = {
     'RedirectOutput': 'REDIRECT_OUTPUT=True',
     'WaitOnNormalExit': 'WAIT_ON_NORMAL_EXIT=True',
     'WaitOnAbnormalExit': 'WAIT_ON_ABNORMAL_EXIT=True',
+    'BreakOnSystemExitZero': 'BREAK_SYSTEMEXIT_ZERO=True',
     'Django': 'DJANGO_DEBUG=True',
     'Flask': 'FLASK_DEBUG=True',
     'Jinja': 'FLASK_DEBUG=True',
@@ -890,6 +892,7 @@ def _parse_debug_options(opts):
     """Debug options are semicolon separated key=value pairs
         WAIT_ON_ABNORMAL_EXIT=True|False
         WAIT_ON_NORMAL_EXIT=True|False
+        BREAK_SYSTEMEXIT_ZERO=True|False
         REDIRECT_OUTPUT=True|False
         VERSION=string
         INTERPRETER_OPTIONS=string
@@ -2570,8 +2573,23 @@ class VSCodeMessageProcessor(VSCLifecycleMsgProcessor):
             exc_name, exc_desc, _, _ = \
                 self._parse_exception_details(resp_args, include_stack=False)
 
-        extra['allThreadsStopped'] = True
+        if not self.debug_options.get('BREAK_SYSTEMEXIT_ZERO', False):
+            # SystemExit is qualified on Python 2, and unqualified on Python 3
+            sysexit_exc_name = 'exceptions.SystemExit' if sys.version_info < (3,) else 'SystemExit'
+            if exc_name == sysexit_exc_name:
+                try:
+                    exit_code = int(exc_desc)
+                except ValueError:
+                    # It is legal to invoke exit() with a non-integer argument, and SystemExit will
+                    # pass that through. It's considered an error exit, same as non-zero integer.
+                    ignore = False
+                else:
+                    ignore = (exit_code == 0)
+                if ignore:
+                    self._resume_all_threads()
+                    return
 
+        extra['allThreadsStopped'] = True
         self.send_event(
             'stopped',
             reason=reason,

tests/func/test_exception.py

@@ -6,6 +6,7 @@ from __future__ import print_function, with_statement, absolute_import
 
 import pytest
 
+from tests.helpers import print
 from tests.helpers.session import DebugSession
 from tests.helpers.timeline import Event
 from tests.helpers.pattern import ANY, Path
@@ -138,3 +139,70 @@ def test_vsc_exception_options_raise_without_except(pyfile, run_as, start_method
             session.send_request('continue').wait_for_response(freeze=False)
 
         session.wait_for_exit()
+
+
+@pytest.mark.parametrize('raised', ['raised', ''])
+@pytest.mark.parametrize('uncaught', ['uncaught', ''])
+@pytest.mark.parametrize('zero', ['zero', ''])
+@pytest.mark.parametrize('exit_code', [0, 1, 'nan'])
+def test_systemexit(pyfile, run_as, start_method, raised, uncaught, zero, exit_code):
+    @pyfile
+    def code_to_debug():
+        from dbgimporter import import_and_enable_debugger
+        import_and_enable_debugger()
+        import sys
+        exit_code = eval(sys.argv[1])
+        print('sys.exit(%r)' % (exit_code,))
+        try:
+            sys.exit(exit_code)
+        except SystemExit:
+            pass
+        sys.exit(exit_code)
+
+    filters = []
+    if raised:
+        filters += ['raised']
+    if uncaught:
+        filters += ['uncaught']
+
+    with DebugSession() as session:
+        session.program_args = [repr(exit_code)]
+        if zero:
+            session.debug_options += ['BreakOnSystemExitZero']
+        session.initialize(
+            target=(run_as, code_to_debug),
+            start_method=start_method,
+            ignore_unobserved=[Event('continued'), Event('stopped')],
+            expected_returncode=ANY.int,
+        )
+        session.send_request('setExceptionBreakpoints', {
+            'filters': filters
+        }).wait_for_response()
+        session.start_debugging()
+
+        # When breaking on raised exceptions, we'll stop on both lines,
+        # unless it's SystemExit(0) and we asked to ignore that.
+        if raised and (zero or exit_code != 0):
+            hit = session.wait_for_thread_stopped(reason='exception')
+            frames = hit.stacktrace.body['stackFrames']
+            assert frames[0]['line'] == 7
+            session.send_request('continue').wait_for_response(freeze=False)
+
+            hit = session.wait_for_thread_stopped(reason='exception')
+            frames = hit.stacktrace.body['stackFrames']
+            assert frames[0]['line'] == 10
+            session.send_request('continue').wait_for_response(freeze=False)
+
+        # When breaking on uncaught exceptions, we'll stop on the second line,
+        # unless it's SystemExit(0) and we asked to ignore that.
+        # Note that if both raised and uncaught filters are set, there will be
+        # two stop for the second line - one for exception being raised, and one
+        # for it unwinding the stack without finding a handler. The block above
+        # takes care of the first stop, so here we just take care of the second.
+        if uncaught and (zero or exit_code != 0):
+            hit = session.wait_for_thread_stopped(reason='exception')
+            frames = hit.stacktrace.body['stackFrames']
+            assert frames[0]['line'] == 10
+            session.send_request('continue').wait_for_response(freeze=False)
+
+        session.wait_for_exit()