Make errors with conditional breakpoints clearer. Fixes microsoft#893

src/debugpy/_vendored/pydevd/_pydevd_bundle/pydevd_api.py

@@ -129,7 +129,8 @@ def set_gui_event_loop(self, py_db, gui_event_loop):
         py_db._gui_event_loop = gui_event_loop
 
     def send_error_message(self, py_db, msg):
-        sys.stderr.write('pydevd: %s\n' % (msg,))
+        cmd = py_db.cmd_factory.make_warning_message('pydevd: %s\n' % (msg,))
+        py_db.writer.add_command(cmd)
 
     def set_show_return_values(self, py_db, show_return_values):
         if show_return_values:

src/debugpy/_vendored/pydevd/_pydevd_bundle/pydevd_process_net_command_json.py

@@ -15,7 +15,7 @@
     ProcessEvent, Scope, ScopesResponseBody, SetExpressionResponseBody,
     SetVariableResponseBody, SourceBreakpoint, SourceResponseBody,
     VariablesResponseBody, SetBreakpointsResponseBody, Response,
-    Capabilities, PydevdAuthorizeRequest, Request, StepInTargetsResponse, StepInTarget,
+    Capabilities, PydevdAuthorizeRequest, Request,
     StepInTargetsResponseBody, SetFunctionBreakpointsResponseBody, BreakpointEvent,
     BreakpointEventBody)
 from _pydevd_bundle.pydevd_api import PyDevdAPI
@@ -35,7 +35,6 @@
 from _pydevd_bundle.pydevd_comm import internal_get_step_in_targets_json
 from _pydevd_bundle.pydevd_additional_thread_info import set_additional_thread_info
 from _pydevd_bundle.pydevd_thread_lifecycle import pydevd_find_thread_by_id
-from _pydev_bundle._pydev_filesystem_encoding import getfilesystemencoding
 
 
 def _convert_rules_to_exclude_filters(rules, on_error):

src/debugpy/_vendored/pydevd/pydevd.py

@@ -23,6 +23,7 @@
 
 import atexit
 import dis
+import io
 from collections import defaultdict
 from contextlib import contextmanager
 from functools import partial
@@ -881,10 +882,14 @@ def handle_breakpoint_condition(self, info, pybreakpoint, new_frame):
             return eval(condition, new_frame.f_globals, new_frame.f_locals)
         except Exception as e:
             if not isinstance(e, self.skip_print_breakpoint_exception):
-                sys.stderr.write('Error while evaluating expression: %s\n' % (condition,))
-
+                stack_trace = io.StringIO()
                 etype, value, tb = sys.exc_info()
-                traceback.print_exception(etype, value, tb.tb_next)
+                traceback.print_exception(etype, value, tb.tb_next, file=stack_trace)
+
+                msg = 'Error while evaluating expression in conditional breakpoint: %s\n%s' % (
+                    condition, stack_trace.getvalue())
+                api = PyDevdAPI()
+                api.send_error_message(self, msg)
 
             if not isinstance(e, self.skip_suspend_on_breakpoint_exception):
                 try:

src/debugpy/_vendored/pydevd/tests_python/debugger_unittest.py

@@ -199,6 +199,7 @@ def __init__(self, sock):
         self._queue = Queue()
         self._kill = False
         self.accept_xml_messages = True
+        self.on_message_found = lambda msg: None
 
     def set_messages_timeout(self, timeout):
         self.MESSAGES_TIMEOUT = timeout
@@ -208,6 +209,7 @@ def get_next_message(self, context_message, timeout=None):
             timeout = self.MESSAGES_TIMEOUT
         try:
             msg = self._queue.get(block=True, timeout=timeout)
+            self.on_message_found(msg)
         except:
             raise TimeoutError('No message was written in %s seconds. Error message:\n%s' % (timeout, context_message,))
         else:

src/debugpy/_vendored/pydevd/tests_python/test_debugger.py

@@ -119,7 +119,7 @@ def test_case_2(case_setup):
 def test_case_breakpoint_condition_exc(case_setup, skip_suspend_on_breakpoint_exception, skip_print_breakpoint_exception):
 
     msgs_in_stderr = (
-        'Error while evaluating expression: i > 5',
+        'Error while evaluating expression in conditional breakpoint: i > 5',
         'Traceback (most recent call last):',
         'File "<string>", line 1, in <module>',
     )
@@ -140,44 +140,53 @@ def _ignore_stderr_line(line):
 
         return False
 
-    def additional_output_checks(stdout, stderr):
-        original_additional_output_checks(stdout, stderr)
-        if skip_print_breakpoint_exception in ([], ['ValueError']):
-            for msg in msgs_in_stderr:
-                assert msg in stderr
-
-            for msg in msgs_one_in_stderr:
-                if msg in stderr:
-                    break
-            else:
-                raise AssertionError('Did not find any of: %s in stderr: %s' % (
-                    msgs_one_in_stderr, stderr))
-        else:
-            for msg in msgs_in_stderr + msgs_one_in_stderr:
-                assert msg not in stderr
-
     with case_setup.test_file('_debugger_case_breakpoint_condition_exc.py') as writer:
 
         original_ignore_stderr_line = writer._ignore_stderr_line
         writer._ignore_stderr_line = _ignore_stderr_line
 
-        original_additional_output_checks = writer.additional_output_checks
-        writer.additional_output_checks = additional_output_checks
-
         writer.write_suspend_on_breakpoint_exception(skip_suspend_on_breakpoint_exception, skip_print_breakpoint_exception)
+
+        expect_print = skip_print_breakpoint_exception in ([], ['ValueError'])
+        expect_suspend = skip_suspend_on_breakpoint_exception in ([], ['ValueError'])
+
         breakpoint_id = writer.write_add_breakpoint(
             writer.get_line_index_with_content('break here'), 'Call', condition='i > 5')
 
+        if not expect_print:
+            _original = writer.reader_thread.on_message_found
+
+            def on_message_found(found_msg):
+                for msg in msgs_in_stderr + msgs_one_in_stderr:
+                    assert msg not in found_msg
+
+            writer.reader_thread.on_message_found = on_message_found
+
         writer.write_make_initial_run()
 
-        if skip_suspend_on_breakpoint_exception in ([], ['ValueError']):
+        def check_error_msg(stderr):
+            for msg in msgs_in_stderr:
+                assert msg in stderr
+
+            for msg in msgs_one_in_stderr:
+                if msg in stderr:
+                    break
+            else:
+                raise AssertionError('Did not find any of: %s in stderr: %s' % (
+                    msgs_one_in_stderr, stderr))
+
+        if expect_print:
+            msg, ctx = writer.wait_for_output()
+            check_error_msg(msg.replace('&gt;', '>'))
+
+        if expect_suspend:
             writer.wait_for_message(CMD_GET_BREAKPOINT_EXCEPTION)
             hit = writer.wait_for_breakpoint_hit()
             writer.write_run_thread(hit.thread_id)
 
         if IS_JYTHON:
             # Jython will break twice.
-            if skip_suspend_on_breakpoint_exception in ([], ['ValueError']):
+            if expect_suspend:
                 writer.wait_for_message(CMD_GET_BREAKPOINT_EXCEPTION)
                 hit = writer.wait_for_breakpoint_hit()
                 writer.write_run_thread(hit.thread_id)

src/debugpy/_vendored/pydevd/tests_python/test_debugger_json.py

@@ -616,6 +616,33 @@ def test_case_json_hit_count_and_step(case_setup):
         writer.finished_ok = True
 
 
+def test_case_json_hit_condition_error(case_setup):
+    with case_setup.test_file('_debugger_case_hit_count.py') as writer:
+        json_facade = JsonFacade(writer)
+
+        json_facade.write_launch()
+        bp = writer.get_line_index_with_content('before loop line')
+        json_facade.write_set_breakpoints(
+            [bp],
+            line_to_info={
+                bp: {'condition': 'range.range.range'}
+        })
+        json_facade.write_make_initial_run()
+
+        def accept_message(msg):
+            if msg.body.category == 'important':
+                if 'Error while evaluating expression in conditional breakpoint' in msg.body.output:
+                    return True
+            return False
+
+        json_facade.wait_for_json_message(OutputEvent, accept_message=accept_message)
+
+        json_facade.wait_for_thread_stopped(line=bp)
+        json_facade.write_continue()
+
+        writer.finished_ok = True
+
+
 def test_case_process_event(case_setup):
     with case_setup.test_file('_debugger_case_change_breaks.py') as writer:
         json_facade = JsonFacade(writer)