Fix diagnostics not being cleared upon foreign document closure

Author: krassowski

atest/04_Interface/DiagnosticsPanel.robot

@@ -9,6 +9,8 @@ Test Teardown     Clean Up
 ${EXPECTED_COUNT}    1
 ${DIAGNOSTIC}     W291 trailing whitespace (pycodestyle)
 ${DIAGNOSTIC MESSAGE}    trailing whitespace
+${DIAGNOSTIC MESSAGE R}    Closing curly-braces should always be on their own line
+${R CELL}         %%R\n{}
 ${MENU COLUMNS}    xpath://div[contains(@class, 'lm-Menu-itemLabel')][contains(text(), "columns")]
 ${LAB MENU}       css:.lm-Menu
 
@@ -78,6 +80,22 @@ Diagnostic Message Can Be Copied
     Close Diagnostics Panel
     Wait Until Element Contains    css:.lsp-statusbar-item    Successfully copied    timeout=10s
 
+Diagnostics Panel Works After Removing Foreign Document
+    Enter Cell Editor    2
+    Lab Command    Insert Cell Below
+    Enter Cell Editor    3
+    Press Keys    None    ${R CELL}
+    Wait Until Keyword Succeeds    10 x    1s    Element Should Contain    ${DIAGNOSTICS PANEL}    ${DIAGNOSTIC MESSAGE}
+    Wait Until Keyword Succeeds    10 x    1s    Element Should Contain    ${DIAGNOSTICS PANEL}    ${DIAGNOSTIC MESSAGE R}
+    Lab Command    Delete Cells
+    # regain focus by entering cell
+    Enter Cell Editor    2
+    # trigger 7 document updates to trigger the garbage collector that removes unused documents
+    # (search for VirtualDocument.remainining_lifetime for more)
+    Press Keys    None    1234567
+    Wait Until Keyword Succeeds    10 x    1s    Element Should Contain    ${DIAGNOSTICS PANEL}    ${DIAGNOSTIC MESSAGE}
+    Wait Until Keyword Succeeds    10 x    1s    Element Should Not Contain    ${DIAGNOSTICS PANEL}    ${DIAGNOSTIC MESSAGE R}
+
 *** Keywords ***
 Expand Menu Entry
     [Arguments]    ${label}

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

@@ -279,9 +279,18 @@ export class DiagnosticsCM extends CodeMirrorIntegration {
     this.adapter.adapterConnected.connect(() =>
       this.switchDiagnosticsPanelSource()
     );
+    this.virtual_document.foreign_document_closed.connect(
+      (document, context) => {
+        this.clearDocumentDiagnostics(context.foreign_document);
+      }
+    );
     super.register();
   }
 
+  clearDocumentDiagnostics(document: VirtualDocument) {
+    this.diagnostics_db.set(document, []);
+  }
+
   private unique_editor_ids: DefaultMap<CodeMirror.Editor, number>;
   private marked_diagnostics: Map<string, CodeMirror.TextMarker> = new Map();
   /**

packages/jupyterlab-lsp/src/virtual/document.ts

@@ -252,7 +252,7 @@ export class VirtualDocument {
     this.unused_standalone_documents = new DefaultMap(
       () => new Array<VirtualDocument>()
     );
-    this._remaining_lifetime = 10;
+    this._remaining_lifetime = 6;
     this.foreign_document_closed = new Signal(this);
     this.foreign_document_opened = new Signal(this);
     this.changed = new Signal(this);