Don't print twice in evaluation if output is being already redirected. …

…Fixes microsoft#827

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

@@ -1161,7 +1161,7 @@ def internal_evaluate_expression_json(py_db, request, thread_id):
     if hasattr(fmt, 'to_dict'):
         fmt = fmt.to_dict()
 
-    if context == 'repl':
+    if context == 'repl' and not py_db.is_output_redirected:
         ctx = pydevd_io.redirect_stream_to_pydb_io_messages_context()
     else:
         ctx = NULL

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

@@ -389,11 +389,15 @@ def get_variable_presentation(setting, default):
         if bool(path_mappings):
             pydevd_file_utils.setup_client_server_paths(path_mappings)
 
+        redirecting = args.get("isOutputRedirected")
         if self._options.redirect_output:
             py_db.enable_output_redirection(True, True)
+            redirecting = True
         else:
             py_db.enable_output_redirection(False, False)
 
+        py_db.is_output_redirected = redirecting
+
         self.api.set_show_return_values(py_db, self._options.show_return_value)
 
         if not self._options.break_system_exit_zero:

src/debugpy/_vendored/pydevd/pydevd.py

@@ -639,6 +639,9 @@ def __init__(self, set_as_global=True):
         self.show_return_values = False
         self.remove_return_values_flag = False
         self.redirect_output = False
+        # Note that besides the `redirect_output` flag, we also need to consider that someone
+        # else is already redirecting (i.e.: debugpy).
+        self.is_output_redirected = False
 
         # this flag disables frame evaluation even if it's available
         self.use_frame_eval = True

src/debugpy/adapter/clients.py

@@ -217,17 +217,22 @@ def handle(self, request):
 
                 arguments = request.arguments
                 if self.launcher:
+                    redirecting = arguments.get("console") == "internalConsole"
                     if "RedirectOutput" in debug_options:
                         # The launcher is doing output redirection, so we don't need the
                         # server to do it, as well.
                         arguments = dict(arguments)
                         arguments["debugOptions"] = list(
                             debug_options - {"RedirectOutput"}
                         )
+                        redirecting = True
 
                     if arguments.get("redirectOutput"):
                         arguments = dict(arguments)
                         del arguments["redirectOutput"]
+                        redirecting = True
+
+                    arguments["isOutputRedirected"] = redirecting
 
                 # pydevd doesn't send "initialized", and responds to the start request
                 # immediately, without waiting for "configurationDone". If it changes

tests/debugpy/test_multiproc.py

@@ -135,6 +135,7 @@ def grandchild(q, a):
 
         expected_child_config = expected_subprocess_config(parent_session)
         child_config = parent_session.wait_for_next_event("debugpyAttach")
+        child_config.pop("isOutputRedirected", None)
         assert child_config == expected_child_config
         parent_session.proceed()
 
@@ -144,6 +145,7 @@ def grandchild(q, a):
 
             expected_grandchild_config = expected_subprocess_config(child_session)
             grandchild_config = child_session.wait_for_next_event("debugpyAttach")
+            grandchild_config.pop("isOutputRedirected", None)
             assert grandchild_config == expected_grandchild_config
 
             with debug.Session(grandchild_config) as grandchild_session:
@@ -204,6 +206,7 @@ def parent():
 
         expected_child_config = expected_subprocess_config(parent_session)
         child_config = parent_session.wait_for_next_event("debugpyAttach")
+        child_config.pop("isOutputRedirected", None)
         assert child_config == expected_child_config
         parent_session.proceed()
 

tests/debugpy/test_output.py

@@ -63,6 +63,43 @@ def code_to_debug():
     assert session.output("stdout").startswith("Hello\tWorld")
 
 
+@pytest.mark.parametrize("redirect_mode", ["internalConsole", "redirectOutput"])
+def test_redirect_output_and_eval(pyfile, target, run, redirect_mode):
+    @pyfile
+    def code_to_debug():
+        import debuggee
+        import sys
+
+        debuggee.setup()
+        sys.stdout.write("line\n")
+        ()  # @wait_for_output
+
+    with debug.Session() as session:
+        if redirect_mode == "redirectOutput":
+            session.config["redirectOutput"] = True
+        elif redirect_mode == "internalConsole":
+            session.config["console"] = "internalConsole"
+        else:
+            raise AssertionError("Unexpected: " + redirect_mode)
+
+        with run(session, target(code_to_debug)):
+            session.set_breakpoints(code_to_debug, all)
+
+        stop = session.wait_for_stop()
+        session.request(
+            "evaluate",
+            {
+                "expression": "sys.stdout.write('evaluated\\n')",
+                "frameId": stop.frame_id,
+                "context": "repl",
+            },
+        )
+
+        session.request_continue()
+
+    assert session.output("stdout") == "line\nevaluated\n"
+
+
 @pytest.mark.parametrize("run", runners.all)
 @pytest.mark.parametrize("redirect", ["enabled", "disabled"])
 def test_redirect_output(pyfile, target, run, redirect):