Ensure that diagnostics panel works after restart

Author: krassowski

atest/04_Interface/DiagnosticsPanel.robot

@@ -28,6 +28,16 @@ Diagnostics Panel Works After Rename
     Wait Until Keyword Succeeds    10 x    1s    Should Have Expected Rows Count    ${EXPECTED_COUNT}
     Clean Up After Working With File    PanelRenamed.ipynb
 
+Diagnostics Panel Works After Kernel Restart
+    [Documentation]    Test for #475 bug
+    Close Diagnostics Panel
+    Lab Command    Restart Kernel…
+    Wait For Dialog
+    Accept Default Dialog Option
+    Wait Until Page Contains Element    css:.cm-lsp-diagnostic[title*="${DIAGNOSTIC}"]    timeout=20s
+    Open Diagnostics Panel
+    Wait Until Keyword Succeeds    10 x    1s    Should Have Expected Rows Count    ${EXPECTED_COUNT}
+
 Diagnostics Panel Can Be Restored
     Close Diagnostics Panel
     Open Diagnostics Panel

packages/jupyterlab-lsp/src/adapters/adapter.ts

@@ -167,20 +167,8 @@ export abstract class WidgetAdapter<T extends IDocumentWidget> {
     this.widget.context.saveState.disconnect(this.on_save_state, this);
     this.connection_manager.closed.disconnect(this.on_connection_closed, this);
     this.widget.disposed.disconnect(this.dispose, this);
-    this.widget.context.model.contentChanged.disconnect(
-      this.onContentChanged,
-      this
-    );
 
-    for (let adapter of this.adapters.values()) {
-      adapter.dispose();
-    }
-    this.adapters.clear();
-
-    this.connection_manager.disconnect_document_signals(
-      this.virtual_editor.virtual_document
-    );
-    this.virtual_editor.dispose();
+    this.disconnect();
 
     // just to be sure
     this.virtual_editor = null;
@@ -224,6 +212,23 @@ export abstract class WidgetAdapter<T extends IDocumentWidget> {
 
   abstract get language_file_extension(): string;
 
+  disconnect() {
+    this.connection_manager.unregister_document(
+      this.virtual_editor.virtual_document
+    );
+    this.widget.context.model.contentChanged.disconnect(
+      this.onContentChanged,
+      this
+    );
+
+    for (let adapter of this.adapters.values()) {
+      adapter.dispose();
+    }
+    this.adapters.clear();
+
+    this.virtual_editor.dispose();
+  }
+
   // equivalent to triggering didClose and didOpen, as per syncing specification,
   // but also reloads the connection; used during file rename (or when it was moved)
   protected reload_connection() {
@@ -233,16 +238,12 @@ export abstract class WidgetAdapter<T extends IDocumentWidget> {
     }
 
     // disconnect all existing connections (and dispose adapters)
-    this.connection_manager.unregister_document(
-      this.virtual_editor.virtual_document
-    );
+    this.disconnect();
 
     // recreate virtual document using current path and language
     // as virtual editor assumes it gets the virtual document at init,
     // just dispose virtual editor (which disposes virtual document too)
     // and re-initialize both virtual editor and document
-    this.virtual_editor.dispose();
-
     this.init_virtual();
 
     // reconnect

packages/jupyterlab-lsp/src/features/diagnostics/diagnostics.ts

@@ -276,6 +276,9 @@ export class DiagnosticsCM extends CodeMirrorIntegration {
     this.wrapper_handlers.set('focusin', this.switchDiagnosticsPanelSource);
     this.unique_editor_ids = new DefaultMap(() => this.unique_editor_ids.size);
     this.settings.changed.connect(this.refreshDiagnostics, this);
+    this.adapter.adapterConnected.connect(() =>
+      this.switchDiagnosticsPanelSource()
+    );
     super.register();
   }
 
@@ -300,7 +303,8 @@ export class DiagnosticsCM extends CodeMirrorIntegration {
 
   switchDiagnosticsPanelSource = () => {
     if (
-      diagnostics_panel.content.model.virtual_editor === this.virtual_editor
+      diagnostics_panel.content.model.virtual_editor === this.virtual_editor &&
+      diagnostics_panel.content.model.diagnostics == this.diagnostics_db
     ) {
       return;
     }
@@ -596,7 +600,9 @@ export class DiagnosticsCM extends CodeMirrorIntegration {
   };
 
   public refreshDiagnostics() {
-    this.setDiagnostics(this.last_response);
+    if (this.last_response) {
+      this.setDiagnostics(this.last_response);
+    }
     diagnostics_panel.update();
   }