Make pipeline metadata available to plugins (#13495)

# Description
Fixes an issue with pipeline metadata not being passed to plugins.

crates/nu-plugin-core/src/interface/mod.rs

@@ -177,16 +177,19 @@ pub trait InterfaceManager {
     ) -> Result<PipelineData, ShellError> {
         self.prepare_pipeline_data(match header {
             PipelineDataHeader::Empty => PipelineData::Empty,
-            PipelineDataHeader::Value(value) => PipelineData::Value(value, None),
+            PipelineDataHeader::Value(value, metadata) => PipelineData::Value(value, metadata),
             PipelineDataHeader::ListStream(info) => {
                 let handle = self.stream_manager().get_handle();
                 let reader = handle.read_stream(info.id, self.get_interface())?;
-                ListStream::new(reader, info.span, signals.clone()).into()
+                let ls = ListStream::new(reader, info.span, signals.clone());
+                PipelineData::ListStream(ls, info.metadata)
             }
             PipelineDataHeader::ByteStream(info) => {
                 let handle = self.stream_manager().get_handle();
                 let reader = handle.read_stream(info.id, self.get_interface())?;
-                ByteStream::from_result_iter(reader, info.span, signals.clone(), info.type_).into()
+                let bs =
+                    ByteStream::from_result_iter(reader, info.span, signals.clone(), info.type_);
+                PipelineData::ByteStream(bs, info.metadata)
             }
         })
     }
@@ -248,26 +251,33 @@ pub trait Interface: Clone + Send {
             Ok::<_, ShellError>((id, writer))
         };
         match self.prepare_pipeline_data(data, context)? {
-            PipelineData::Value(value, ..) => {
+            PipelineData::Value(value, metadata) => Ok((
-                Ok((PipelineDataHeader::Value(value), PipelineDataWriter::None))
+                PipelineDataHeader::Value(value, metadata),
-            }
+                PipelineDataWriter::None,
+            )),
             PipelineData::Empty => Ok((PipelineDataHeader::Empty, PipelineDataWriter::None)),
-            PipelineData::ListStream(stream, ..) => {
+            PipelineData::ListStream(stream, metadata) => {
                 let (id, writer) = new_stream(LIST_STREAM_HIGH_PRESSURE)?;
                 Ok((
                     PipelineDataHeader::ListStream(ListStreamInfo {
                         id,
                         span: stream.span(),
+                        metadata,
                     }),
                     PipelineDataWriter::ListStream(writer, stream),
                 ))
             }
-            PipelineData::ByteStream(stream, ..) => {
+            PipelineData::ByteStream(stream, metadata) => {
                 let span = stream.span();
                 let type_ = stream.type_();
                 if let Some(reader) = stream.reader() {
                     let (id, writer) = new_stream(RAW_STREAM_HIGH_PRESSURE)?;
-                    let header = PipelineDataHeader::ByteStream(ByteStreamInfo { id, span, type_ });
+                    let header = PipelineDataHeader::ByteStream(ByteStreamInfo {
+                        id,
+                        span,
+                        type_,
+                        metadata,
+                    });
                     Ok((header, PipelineDataWriter::ByteStream(writer, reader)))
                 } else {
                     Ok((PipelineDataHeader::Empty, PipelineDataWriter::None))

crates/nu-plugin-core/src/interface/tests.rs

@@ -137,10 +137,16 @@ fn read_pipeline_data_empty() -> Result<(), ShellError> {
 fn read_pipeline_data_value() -> Result<(), ShellError> {
     let manager = TestInterfaceManager::new(&TestCase::new());
     let value = Value::test_int(4);
-    let header = PipelineDataHeader::Value(value.clone());
+    let metadata = Some(PipelineMetadata {
-
+        data_source: DataSource::FilePath("/test/path".into()),
+        content_type: None,
+    });
+    let header = PipelineDataHeader::Value(value.clone(), metadata.clone());
     match manager.read_pipeline_data(header, &Signals::empty())? {
-        PipelineData::Value(read_value, ..) => assert_eq!(value, read_value),
+        PipelineData::Value(read_value, read_metadata) => {
+            assert_eq!(value, read_value);
+            assert_eq!(metadata, read_metadata);
+        }
         PipelineData::ListStream(..) => panic!("unexpected ListStream"),
         PipelineData::ByteStream(..) => panic!("unexpected ByteStream"),
         PipelineData::Empty => panic!("unexpected Empty"),
@@ -161,9 +167,15 @@ fn read_pipeline_data_list_stream() -> Result<(), ShellError> {
     }
     test.add(StreamMessage::End(7));
 
+    let metadata = Some(PipelineMetadata {
+        data_source: DataSource::None,
+        content_type: Some("foobar".into()),
+    });
+
     let header = PipelineDataHeader::ListStream(ListStreamInfo {
         id: 7,
         span: Span::test_data(),
+        metadata,
     });
 
     let pipe = manager.read_pipeline_data(header, &Signals::empty())?;
@@ -204,10 +216,17 @@ fn read_pipeline_data_byte_stream() -> Result<(), ShellError> {
     test.add(StreamMessage::End(12));
 
     let test_span = Span::new(10, 13);
+
+    let metadata = Some(PipelineMetadata {
+        data_source: DataSource::None,
+        content_type: Some("foobar".into()),
+    });
+
     let header = PipelineDataHeader::ByteStream(ByteStreamInfo {
         id: 12,
         span: test_span,
         type_: ByteStreamType::Unknown,
+        metadata,
     });
 
     let pipe = manager.read_pipeline_data(header, &Signals::empty())?;
@@ -251,9 +270,15 @@ fn read_pipeline_data_byte_stream() -> Result<(), ShellError> {
 #[test]
 fn read_pipeline_data_prepared_properly() -> Result<(), ShellError> {
     let manager = TestInterfaceManager::new(&TestCase::new());
+    let metadata = Some(PipelineMetadata {
+        data_source: DataSource::None,
+        content_type: Some("foobar".into()),
+    });
+
     let header = PipelineDataHeader::ListStream(ListStreamInfo {
         id: 0,
         span: Span::test_data(),
+        metadata,
     });
     match manager.read_pipeline_data(header, &Signals::empty())? {
         PipelineData::ListStream(_, meta) => match meta {
@@ -301,7 +326,7 @@ fn write_pipeline_data_value() -> Result<(), ShellError> {
         interface.init_write_pipeline_data(PipelineData::Value(value.clone(), None), &())?;
 
     match header {
-        PipelineDataHeader::Value(read_value) => assert_eq!(value, read_value),
+        PipelineDataHeader::Value(read_value, _) => assert_eq!(value, read_value),
         _ => panic!("unexpected header: {header:?}"),
     }
 

crates/nu-plugin-core/src/serializers/tests.rs

@@ -6,7 +6,8 @@ macro_rules! generate_tests {
             StreamData,
         };
         use nu_protocol::{
-            LabeledError, PluginSignature, Signature, Span, Spanned, SyntaxShape, Value,
+            DataSource, LabeledError, PipelineMetadata, PluginSignature, Signature, Span, Spanned,
+            SyntaxShape, Value,
         };
 
         #[test]
@@ -123,10 +124,15 @@ macro_rules! generate_tests {
                 )],
             };
 
+            let metadata = Some(PipelineMetadata {
+                data_source: DataSource::None,
+                content_type: Some("foobar".into()),
+            });
+
             let plugin_call = PluginCall::Run(CallInfo {
                 name: name.clone(),
                 call: call.clone(),
-                input: PipelineDataHeader::Value(input.clone()),
+                input: PipelineDataHeader::Value(input.clone(), metadata.clone()),
             });
 
             let plugin_input = PluginInput::Call(1, plugin_call);
@@ -144,7 +150,7 @@ macro_rules! generate_tests {
             match returned {
                 PluginInput::Call(1, PluginCall::Run(call_info)) => {
                     assert_eq!(name, call_info.name);
-                    assert_eq!(PipelineDataHeader::Value(input), call_info.input);
+                    assert_eq!(PipelineDataHeader::Value(input, metadata), call_info.input);
                     assert_eq!(call.head, call_info.call.head);
                     assert_eq!(call.positional.len(), call_info.call.positional.len());
 
@@ -305,7 +311,7 @@ macro_rules! generate_tests {
             match returned {
                 PluginOutput::CallResponse(
                     4,
-                    PluginCallResponse::PipelineData(PipelineDataHeader::Value(returned_value)),
+                    PluginCallResponse::PipelineData(PipelineDataHeader::Value(returned_value, _)),
                 ) => {
                     assert_eq!(value, returned_value)
                 }
@@ -325,7 +331,7 @@ macro_rules! generate_tests {
                 span,
             );
 
-            let response = PluginCallResponse::PipelineData(PipelineDataHeader::Value(value));
+            let response = PluginCallResponse::PipelineData(PipelineDataHeader::value(value));
             let output = PluginOutput::CallResponse(5, response);
 
             let encoder = $encoder;
@@ -341,7 +347,7 @@ macro_rules! generate_tests {
             match returned {
                 PluginOutput::CallResponse(
                     5,
-                    PluginCallResponse::PipelineData(PipelineDataHeader::Value(returned_value)),
+                    PluginCallResponse::PipelineData(PipelineDataHeader::Value(returned_value, _)),
                 ) => {
                     assert_eq!(span, returned_value.span());
 

crates/nu-plugin-engine/src/interface/tests.rs

@@ -17,8 +17,9 @@ use nu_plugin_protocol::{
 use nu_protocol::{
     ast::{Math, Operator},
     engine::Closure,
-    ByteStreamType, CustomValue, IntoInterruptiblePipelineData, IntoSpanned, PipelineData,
+    ByteStreamType, CustomValue, DataSource, IntoInterruptiblePipelineData, IntoSpanned,
-    PluginMetadata, PluginSignature, ShellError, Signals, Span, Spanned, Value,
+    PipelineData, PipelineMetadata, PluginMetadata, PluginSignature, ShellError, Signals, Span,
+    Spanned, Value,
 };
 use serde::{Deserialize, Serialize};
 use std::{
@@ -52,10 +53,7 @@ fn manager_consume_all_exits_after_streams_and_interfaces_are_dropped() -> Resul
 
     // Create a stream...
     let stream = manager.read_pipeline_data(
-        PipelineDataHeader::ListStream(ListStreamInfo {
+        PipelineDataHeader::list_stream(ListStreamInfo::new(0, Span::test_data())),
-            id: 0,
-            span: Span::test_data(),
-        }),
         &Signals::empty(),
     )?;
 
@@ -108,10 +106,7 @@ fn manager_consume_all_propagates_io_error_to_readers() -> Result<(), ShellError
     test.set_read_error(test_io_error());
 
     let stream = manager.read_pipeline_data(
-        PipelineDataHeader::ListStream(ListStreamInfo {
+        PipelineDataHeader::list_stream(ListStreamInfo::new(0, Span::test_data())),
-            id: 0,
-            span: Span::test_data(),
-        }),
         &Signals::empty(),
     )?;
 
@@ -154,11 +149,11 @@ fn manager_consume_all_propagates_message_error_to_readers() -> Result<(), Shell
     test.add(invalid_output());
 
     let stream = manager.read_pipeline_data(
-        PipelineDataHeader::ByteStream(ByteStreamInfo {
+        PipelineDataHeader::byte_stream(ByteStreamInfo::new(
-            id: 0,
+            0,
-            span: Span::test_data(),
+            Span::test_data(),
-            type_: ByteStreamType::Unknown,
+            ByteStreamType::Unknown,
-        }),
+        )),
         &Signals::empty(),
     )?;
 
@@ -331,10 +326,10 @@ fn manager_consume_call_response_forwards_to_subscriber_with_pipeline_data(
 
     manager.consume(PluginOutput::CallResponse(
         0,
-        PluginCallResponse::PipelineData(PipelineDataHeader::ListStream(ListStreamInfo {
+        PluginCallResponse::PipelineData(PipelineDataHeader::list_stream(ListStreamInfo::new(
-            id: 0,
+            0,
-            span: Span::test_data(),
+            Span::test_data(),
-        })),
+        ))),
     ))?;
 
     for i in 0..2 {
@@ -375,18 +370,18 @@ fn manager_consume_call_response_registers_streams() -> Result<(), ShellError> {
     // Check list streams, byte streams
     manager.consume(PluginOutput::CallResponse(
         0,
-        PluginCallResponse::PipelineData(PipelineDataHeader::ListStream(ListStreamInfo {
+        PluginCallResponse::PipelineData(PipelineDataHeader::list_stream(ListStreamInfo::new(
-            id: 0,
+            0,
-            span: Span::test_data(),
+            Span::test_data(),
-        })),
+        ))),
     ))?;
     manager.consume(PluginOutput::CallResponse(
         1,
-        PluginCallResponse::PipelineData(PipelineDataHeader::ByteStream(ByteStreamInfo {
+        PluginCallResponse::PipelineData(PipelineDataHeader::byte_stream(ByteStreamInfo::new(
-            id: 1,
+            1,
-            span: Span::test_data(),
+            Span::test_data(),
-            type_: ByteStreamType::Unknown,
+            ByteStreamType::Unknown,
-        })),
+        ))),
     ))?;
 
     // ListStream should have one
@@ -442,10 +437,7 @@ fn manager_consume_engine_call_forwards_to_subscriber_with_pipeline_data() -> Re
                 span: Span::test_data(),
             },
             positional: vec![],
-            input: PipelineDataHeader::ListStream(ListStreamInfo {
+            input: PipelineDataHeader::list_stream(ListStreamInfo::new(2, Span::test_data())),
-                id: 2,
-                span: Span::test_data(),
-            }),
             redirect_stdout: false,
             redirect_stderr: false,
         },
@@ -806,6 +798,11 @@ fn interface_write_plugin_call_writes_run_with_value_input() -> Result<(), Shell
     let manager = test.plugin("test");
     let interface = manager.get_interface();
 
+    let metadata0 = PipelineMetadata {
+        data_source: DataSource::None,
+        content_type: Some("baz".into()),
+    };
+
     let result = interface.write_plugin_call(
         PluginCall::Run(CallInfo {
             name: "foo".into(),
@@ -814,7 +811,7 @@ fn interface_write_plugin_call_writes_run_with_value_input() -> Result<(), Shell
                 positional: vec![],
                 named: vec![],
             },
-            input: PipelineData::Value(Value::test_int(-1), None),
+            input: PipelineData::Value(Value::test_int(-1), Some(metadata0.clone())),
         }),
         None,
     )?;
@@ -826,7 +823,10 @@ fn interface_write_plugin_call_writes_run_with_value_input() -> Result<(), Shell
             PluginCall::Run(CallInfo { name, input, .. }) => {
                 assert_eq!("foo", name);
                 match input {
-                    PipelineDataHeader::Value(value) => assert_eq!(-1, value.as_int()?),
+                    PipelineDataHeader::Value(value, metadata) => {
+                        assert_eq!(-1, value.as_int()?);
+                        assert_eq!(metadata0, metadata.expect("there should be metadata"));
+                    }
                     _ => panic!("unexpected input header: {input:?}"),
                 }
             }

crates/nu-plugin-protocol/src/lib.rs

@@ -23,7 +23,7 @@ pub mod test_util;
 
 use nu_protocol::{
     ast::Operator, engine::Closure, ByteStreamType, Config, DeclId, LabeledError, PipelineData,
-    PluginMetadata, PluginSignature, ShellError, Span, Spanned, Value,
+    PipelineMetadata, PluginMetadata, PluginSignature, ShellError, Span, Spanned, Value,
 };
 use nu_utils::SharedCow;
 use serde::{Deserialize, Serialize};
@@ -78,7 +78,7 @@ pub enum PipelineDataHeader {
     /// No input
     Empty,
     /// A single value
-    Value(Value),
+    Value(Value, Option<PipelineMetadata>),
     /// Initiate [`nu_protocol::PipelineData::ListStream`].
     ///
     /// Items are sent via [`StreamData`]
@@ -94,11 +94,23 @@ impl PipelineDataHeader {
     pub fn stream_id(&self) -> Option<StreamId> {
         match self {
             PipelineDataHeader::Empty => None,
-            PipelineDataHeader::Value(_) => None,
+            PipelineDataHeader::Value(_, _) => None,
             PipelineDataHeader::ListStream(info) => Some(info.id),
             PipelineDataHeader::ByteStream(info) => Some(info.id),
         }
     }
+
+    pub fn value(value: Value) -> Self {
+        PipelineDataHeader::Value(value, None)
+    }
+
+    pub fn list_stream(info: ListStreamInfo) -> Self {
+        PipelineDataHeader::ListStream(info)
+    }
+
+    pub fn byte_stream(info: ByteStreamInfo) -> Self {
+        PipelineDataHeader::ByteStream(info)
+    }
 }
 
 /// Additional information about list (value) streams
@@ -106,6 +118,18 @@ impl PipelineDataHeader {
 pub struct ListStreamInfo {
     pub id: StreamId,
     pub span: Span,
+    pub metadata: Option<PipelineMetadata>,
+}
+
+impl ListStreamInfo {
+    /// Create a new `ListStreamInfo` with a unique ID
+    pub fn new(id: StreamId, span: Span) -> Self {
+        ListStreamInfo {
+            id,
+            span,
+            metadata: None,
+        }
+    }
 }
 
 /// Additional information about byte streams
@@ -115,6 +139,19 @@ pub struct ByteStreamInfo {
     pub span: Span,
     #[serde(rename = "type")]
     pub type_: ByteStreamType,
+    pub metadata: Option<PipelineMetadata>,
+}
+
+impl ByteStreamInfo {
+    /// Create a new `ByteStreamInfo` with a unique ID
+    pub fn new(id: StreamId, span: Span, type_: ByteStreamType) -> Self {
+        ByteStreamInfo {
+            id,
+            span,
+            type_,
+            metadata: None,
+        }
+    }
 }
 
 /// Calls that a plugin can execute. The type parameter determines the input type.
@@ -344,7 +381,7 @@ impl PluginCallResponse<PipelineDataHeader> {
         if value.is_nothing() {
             PluginCallResponse::PipelineData(PipelineDataHeader::Empty)
         } else {
-            PluginCallResponse::PipelineData(PipelineDataHeader::Value(value))
+            PluginCallResponse::PipelineData(PipelineDataHeader::value(value))
         }
     }
 }

crates/nu-plugin/src/plugin/interface/tests.rs

@@ -55,10 +55,7 @@ fn manager_consume_all_exits_after_streams_and_interfaces_are_dropped() -> Resul
 
     // Create a stream...
     let stream = manager.read_pipeline_data(
-        PipelineDataHeader::ListStream(ListStreamInfo {
+        PipelineDataHeader::list_stream(ListStreamInfo::new(0, Span::test_data())),
-            id: 0,
-            span: Span::test_data(),
-        }),
         &Signals::empty(),
     )?;
 
@@ -111,10 +108,7 @@ fn manager_consume_all_propagates_io_error_to_readers() -> Result<(), ShellError
     test.set_read_error(test_io_error());
 
     let stream = manager.read_pipeline_data(
-        PipelineDataHeader::ListStream(ListStreamInfo {
+        PipelineDataHeader::list_stream(ListStreamInfo::new(0, Span::test_data())),
-            id: 0,
-            span: Span::test_data(),
-        }),
         &Signals::empty(),
     )?;
 
@@ -157,11 +151,11 @@ fn manager_consume_all_propagates_message_error_to_readers() -> Result<(), Shell
     test.add(invalid_input());
 
     let stream = manager.read_pipeline_data(
-        PipelineDataHeader::ByteStream(ByteStreamInfo {
+        PipelineDataHeader::byte_stream(ByteStreamInfo::new(
-            id: 0,
+            0,
-            span: Span::test_data(),
+            Span::test_data(),
-            type_: ByteStreamType::Unknown,
+            ByteStreamType::Unknown,
-        }),
+        )),
         &Signals::empty(),
     )?;
 
@@ -414,10 +408,7 @@ fn manager_consume_call_run_forwards_to_receiver_with_pipeline_data() -> Result<
                 positional: vec![],
                 named: vec![],
             },
-            input: PipelineDataHeader::ListStream(ListStreamInfo {
+            input: PipelineDataHeader::list_stream(ListStreamInfo::new(6, Span::test_data())),
-                id: 6,
-                span: Span::test_data(),
-            }),
         }),
     ))?;
 
@@ -556,10 +547,10 @@ fn manager_consume_engine_call_response_forwards_to_subscriber_with_pipeline_dat
 
     manager.consume(PluginInput::EngineCallResponse(
         0,
-        EngineCallResponse::PipelineData(PipelineDataHeader::ListStream(ListStreamInfo {
+        EngineCallResponse::PipelineData(PipelineDataHeader::list_stream(ListStreamInfo::new(
-            id: 0,
+            0,
-            span: Span::test_data(),
+            Span::test_data(),
-        })),
+        ))),
     ))?;
 
     for i in 0..2 {
@@ -707,7 +698,7 @@ fn interface_write_response_with_value() -> Result<(), ShellError> {
             assert_eq!(33, id, "id");
             match response {
                 PluginCallResponse::PipelineData(header) => match header {
-                    PipelineDataHeader::Value(value) => assert_eq!(6, value.as_int()?),
+                    PipelineDataHeader::Value(value, _) => assert_eq!(6, value.as_int()?),
                     _ => panic!("unexpected pipeline data header: {header:?}"),
                 },
                 _ => panic!("unexpected response: {response:?}"),

crates/nu-protocol/src/pipeline/metadata.rs

@@ -1,7 +1,9 @@
 use std::path::PathBuf;
 
+use serde::{Deserialize, Serialize};
+
 /// Metadata that is valid for the whole [`PipelineData`](crate::PipelineData)
-#[derive(Debug, Default, Clone)]
+#[derive(Clone, Debug, Default, Deserialize, Eq, PartialEq, Serialize)]
 pub struct PipelineMetadata {
     pub data_source: DataSource,
     pub content_type: Option<String>,
@@ -27,7 +29,7 @@ impl PipelineMetadata {
 ///
 /// This can either be a particular family of commands (useful so downstream commands can adjust
 /// the presentation e.g. `Ls`) or the opened file to protect against overwrite-attempts properly.
-#[derive(Debug, Default, Clone)]
+#[derive(Clone, Debug, Default, Deserialize, Eq, PartialEq, Serialize)]
 pub enum DataSource {
     Ls,
     HtmlThemes,

crates/nu_plugin_nu_example/nu_plugin_nu_example.nu

@@ -7,7 +7,7 @@
 # language without adding any extra dependencies to our tests.
 
 const NUSHELL_VERSION = "0.96.2"
-const PLUGIN_VERSION = "0.1.0" # bump if you change commands!
+const PLUGIN_VERSION = "0.1.1" # bump if you change commands!
 
 def main [--stdio] {
   if ($stdio) {
@@ -133,7 +133,7 @@ def process_call [
 
   # Create a Value of type List that will be encoded and sent to Nushell
   let value = {
-    Value: {
+    Value: [{
       List: {
         vals: (0..9 | each { |x|
           {
@@ -157,7 +157,7 @@ def process_call [
         }),
         span: $span
       }
-    }
+    }, null]
   }
 
   write_response $id { PipelineData: $value }

crates/nu_plugin_python/nu_plugin_python_example.py

@@ -28,7 +28,7 @@ import json
 
 
 NUSHELL_VERSION = "0.96.2"
-PLUGIN_VERSION = "0.1.0" # bump if you change commands!
+PLUGIN_VERSION = "0.1.1"  # bump if you change commands!
 
 
 def signatures():
@@ -125,15 +125,12 @@ def process_call(id, plugin_call):
     span = plugin_call["call"]["head"]
 
     # Creates a Value of type List that will be encoded and sent to Nushell
-    def f(x, y): return {
+    def f(x, y):
-        "Int": {
+        return {"Int": {"val": x * y, "span": span}}
-            "val": x * y,
-            "span": span
-        }
-    }
 
     value = {
-        "Value": {
+        "Value": [
+            {
                 "List": {
                     "vals": [
                         {
@@ -143,13 +140,16 @@ def process_call(id, plugin_call):
                                     "two": f(x, 1),
                                     "three": f(x, 2),
                                 },
-                            "span": span
+                                "span": span,
                             }
-                    } for x in range(0, 10)
+                        }
+                        for x in range(0, 10)
                     ],
-                "span": span
+                    "span": span,
-            }
                 }
+            },
+            None,
+        ]
     }
 
     write_response(id, {"PipelineData": value})
@@ -172,7 +172,7 @@ def tell_nushell_hello():
         "Hello": {
             "protocol": "nu-plugin",  # always this value
             "version": NUSHELL_VERSION,
-            "features": []
+            "features": [],
         }
     }
     sys.stdout.write(json.dumps(hello))
@@ -200,7 +200,8 @@ def write_error(id, text, span=None):
     Use this error format to send errors to nushell in response to a plugin call. The ID of the
     plugin call is required.
     """
-    error = {
+    error = (
+        {
             "Error": {
                 "msg": "ERROR from plugin",
                 "labels": [
@@ -210,12 +211,15 @@ def write_error(id, text, span=None):
                     }
                 ],
             }
-    } if span is not None else {
+        }
+        if span is not None
+        else {
             "Error": {
                 "msg": "ERROR from plugin",
                 "help": text,
             }
         }
+    )
     write_response(id, error)
 
 
@@ -230,11 +234,14 @@ def handle_input(input):
     elif "Call" in input:
         [id, plugin_call] = input["Call"]
         if plugin_call == "Metadata":
-            write_response(id, {
+            write_response(
+                id,
+                {
                     "Metadata": {
                         "version": PLUGIN_VERSION,
                     }
-            })
+                },
+            )
         elif plugin_call == "Signature":
             write_response(id, signatures())
         elif "Run" in plugin_call:

crates/nu_plugin_stress_internals/src/main.rs

@@ -178,7 +178,7 @@ fn handle_message(
                             id,
                             {
                                 "PipelineData": {
-                                    "Value": return_value
+                                    "Value": [return_value, null]
                                 }
                             }
                         ]