Fixes exception shown when exec throws exception. Fixes #1234 (#1246)

* Fixes exception shown when exec throws exception

* Add comment

* Add tests

src/ptvsd/_vendored/pydevd/_pydevd_bundle/pydevd_comm.py

@@ -897,8 +897,10 @@ def internal_evaluate_expression_json(py_db, request, thread_id):
         elif context == 'repl':
             try:
                 pydevd_vars.evaluate_expression(py_db, frame, expression, is_exec=True)
-            except:
-                pass
+            except Exception as ex:
+                err = ''.join(traceback.format_exception_only(type(ex), ex))
+                _evaluate_response(py_db, request, result='', error_message=err)
+                return
             # No result on exec.
             _evaluate_response(py_db, request, result='')
             return

src/ptvsd/_vendored/pydevd/tests_python/resources/_debugger_case_evaluate.py

@@ -0,0 +1,8 @@
+def Call():
+    var_1 = 5
+
+    var_all = 1  # Break here
+
+if __name__ == '__main__':
+    Call()
+    print('TEST SUCEEDED!')

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

@@ -939,6 +939,49 @@ def test_stepping(case_setup):
 
         writer.finished_ok = True
 
+def test_evaluate(case_setup):
+    with case_setup.test_file('_debugger_case_evaluate.py') as writer:
+        json_facade = JsonFacade(writer)
+
+        writer.write_set_protocol('http_json')
+        writer.write_add_breakpoint(writer.get_line_index_with_content('Break here'))
+
+        json_facade.write_make_initial_run()
+
+        hit = writer.wait_for_breakpoint_hit()
+
+        stack_trace_request = json_facade.write_request(
+            pydevd_schema.StackTraceRequest(pydevd_schema.StackTraceArguments(threadId=hit.thread_id)))
+        stack_trace_response = json_facade.wait_for_response(stack_trace_request)
+        stack_frame = next(iter(stack_trace_response.body.stackFrames))
+        stack_frame_id = stack_frame['id']
+
+        # Test evaluate request that results in 'eval'
+        eval_request = json_facade.write_request(
+            pydevd_schema.EvaluateRequest(pydevd_schema.EvaluateArguments('var_1', frameId=stack_frame_id, context='repl')))
+        eval_response = json_facade.wait_for_response(eval_request)
+        assert eval_response.body.result == '5'
+        assert eval_response.body.type == 'int'
+
+        # Test evaluate request that results in 'exec'
+        exec_request = json_facade.write_request(
+            pydevd_schema.EvaluateRequest(pydevd_schema.EvaluateArguments('var_1 = 6', frameId=stack_frame_id, context='repl')))
+        exec_response = json_facade.wait_for_response(exec_request)
+        assert exec_response.body.result == ''
+
+        # Test evaluate request that results in 'exec' but fails
+        exec_request = json_facade.write_request(
+            pydevd_schema.EvaluateRequest(pydevd_schema.EvaluateArguments('var_1 = "abc"/6', frameId=stack_frame_id, context='repl')))
+        exec_response = json_facade.wait_for_response(exec_request)
+        assert exec_response.success == False
+        assert exec_response.body.result == ''
+        assert exec_response.message.find('TypeError') > -1
+
+        writer.write_run_thread(hit.thread_id)
+
+        writer.finished_ok = True
+
+
 
 @pytest.mark.skipif(IS_JYTHON, reason='Flaky on Jython.')
 def test_path_translation_and_source_reference(case_setup):

src/ptvsd/wrapper.py

@@ -1656,6 +1656,11 @@ class VSCodeMessageProcessor(VSCLifecycleMsgProcessor):
             is_json=True)
 
         body = resp_args['body']
+
+        # Currently there is an issue in VSC where returning success=false for a eval request,
+        # in repl context. VSC does not show the error response in the debug console.
+        if args.get('context', None) == 'repl' and not resp_args['success']:
+            body['result'] = resp_args['message']
         self.send_response(request, **body)
 
     @async_handler