More backports to 2.x

atest/03_Notebook.robot

@@ -66,7 +66,40 @@ Foreign Extractors
 Code Overrides
     ${file} =    Set Variable    Code overrides.ipynb
     Setup Notebook    Python    ${file}
-    ${virtual_path} =    Set Variable    ${VIRTUALDOCS DIR}${/}Code overrides.ipynb
+    ${virtual_path} =    Set Variable    ${VIRTUALDOCS DIR}${/}${file}
     Wait Until Created    ${virtual_path}
     ${document} =    Get File    ${virtual_path}
     Should Be Equal    ${document}    get_ipython().run_line_magic("ls", "")\n\n\nget_ipython().run_line_magic("pip", " freeze")\n
+    [Teardown]    Clean Up After Working With File    Code overrides.ipynb
+
+Adding Text To Cells Is Reflected In Virtual Document
+    ${file} =    Set Variable    Empty.ipynb
+    Setup Notebook    Python    ${file}
+    ${virtual_path} =    Set Variable    ${VIRTUALDOCS DIR}${/}${file}
+    Wait Until Created    ${virtual_path}
+    Enter Cell Editor    1
+    Press Keys    None    cell_1
+    Lab Command    Insert Cell Below
+    Enter Cell Editor    2
+    Press Keys    None    cell_2
+    Wait Until Keyword Succeeds    3x    1s    File Content Should Be Equal    ${virtual_path}    cell_1\n\n\ncell_2\n
+    [Teardown]    Clean Up After Working With File    Empty.ipynb
+
+Adding Text To Cells After Kernel Restart
+    ${file} =    Set Variable    Empty.ipynb
+    Setup Notebook    Python    ${file}
+    ${virtual_path} =    Set Variable    ${VIRTUALDOCS DIR}${/}${file}
+    Wait Until Created    ${virtual_path}
+    Enter Cell Editor    1
+    Lab Command    Insert Cell Below
+    Enter Cell Editor    2    line=1
+    Press Keys    None    text
+    Wait Until Keyword Succeeds    3x    1s    File Content Should Be Equal    ${virtual_path}    \n\n\ntext\n
+    [Teardown]    Clean Up After Working With File    Empty.ipynb
+
+*** Keywords ***
+File Content Should Be Equal
+    [Arguments]    ${file}    ${text}
+    Wait Until Keyword Succeeds    5x    1s    File Should Not Be Empty    ${file}
+    ${document} =    Get File    ${file}
+    Should Be Equal    ${document}    ${text}

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

atest/04_Interface/Statusbar.robot

@@ -22,10 +22,7 @@ Statusbar Popup Opens
 Status Changes Between Notebooks
     Setup Notebook    Python    Python.ipynb
     Wait Until Fully Initialized
-    Lab Command    New Notebook
-    Wait For Dialog
-    # Kernel selection dialog shows up, accept Python as default kernel
-    Accept Default Dialog Option
+    Open New Notebook
     Element Should Contain    ${STATUSBAR}    Waiting...
     Wait Until Fully Initialized
     Switch To Tab    Python.ipynb

atest/05_Features/Completion.robot

@@ -28,6 +28,7 @@ Works With Kernel Running
 
 Works When Kernel Is Shut Down
     Lab Command    Shut Down All Kernels…
+    Wait For Dialog
     Capture Page Screenshot    01-shutting-kernels.png
     Accept Default Dialog Option
     Capture Page Screenshot    02-kernels-shut.png
@@ -39,6 +40,21 @@ Works When Kernel Is Shut Down
     # this comes from kernel:
     Completer Should Not Suggest    %%timeit
 
+Works After Kernel Restart In New Cells
+    Lab Command    Restart Kernel…
+    Wait For Dialog
+    Accept Default Dialog Option
+    Enter Cell Editor    1    line=2
+    # works in old cells
+    Trigger Completer
+    Completer Should Suggest    test
+    Lab Command    Insert Cell Below
+    Enter Cell Editor    2    line=1
+    # works in new cells
+    Press Keys    None    lis
+    Trigger Completer
+    Completer Should Suggest    list
+
 Works In File Editor
     Prepare File for Editing    Python    completion    completion.py
     Place Cursor In File Editor At    9    2

atest/Keywords.robot

@@ -389,3 +389,14 @@ Measure Cursor Position
     Wait Until Page Contains Element    ${CM CURSORS}
     ${position} =    Wait Until Keyword Succeeds    20 x    0.05s    Get Vertical Position    ${CM CURSOR}
     [Return]    ${position}
+
+Switch To Tab
+    [Arguments]    ${file}
+    Click Element    ${JLAB XP DOCK TAB}\[contains(., '${file}')]
+
+Open New Notebook
+    Lab Command    New Notebook
+    Wait For Dialog
+    # Kernel selection dialog shows up, accept Python as default kernel
+    Accept Default Dialog Option
+

atest/examples/Empty.ipynb

@@ -0,0 +1,32 @@
+{
+ "cells": [
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": []
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 3",
+   "language": "python",
+   "name": "python3"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 3
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython3",
+   "version": "3.7.9"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 4
+}

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

@@ -165,20 +165,8 @@ 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;
@@ -222,6 +210,31 @@ 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
+    );
+
+    // pretend that all editors were removed to trigger the disconnection of even handlers
+    // they will be connected again on new connection
+    for (let editor of this.editors) {
+      this.editorRemoved.emit({
+        editor: editor
+      });
+    }
+
+    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() {
@@ -231,15 +244,18 @@ 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
-    let virtual_document = this.create_virtual_document();
-    this.virtual_editor.virtual_document = virtual_document;
+    // 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.init_virtual();
+
     // reconnect
-    this.connect_document(virtual_document, true).catch(console.warn);
+    this.connect_document(this.virtual_editor.virtual_document, true).catch(
+      console.warn
+    );
   }
 
   protected on_save_state(context: any, state: DocumentRegistry.SaveState) {
@@ -361,6 +377,7 @@ export abstract class WidgetAdapter<T extends IDocumentWidget> {
       return;
     }
     this.virtual_editor = virtual_editor;
+    this.connect_contentChanged_signal();
   }
 
   /**
@@ -507,7 +524,7 @@ export abstract class WidgetAdapter<T extends IDocumentWidget> {
    * (range) updates this can be still implemented by comparison of before/after states of the
    * virtual documents, which is even more resilient and -obviously - editor-independent.
    */
-  connect_contentChanged_signal() {
+  private connect_contentChanged_signal() {
     this.widget.context.model.contentChanged.connect(
       this.onContentChanged,
       this

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

@@ -46,7 +46,6 @@ export class FileEditorAdapter extends WidgetAdapter<
     this.editor = editor_widget.content;
 
     this.init_virtual();
-    this.connect_contentChanged_signal();
 
     console.log('LSP: file ready for connection:', this.path);