Add restart method to the service

src/index.ts

@@ -299,8 +299,7 @@ const main: JupyterFrontEndPlugin<IDebugger> = {
         return service.isThreadStopped();
       },
       execute: async () => {
-        await service.stop();
-        await service.start();
+        await service.restart();
         commands.notifyCommandChanged();
       }
     });

src/service.ts

@@ -172,6 +172,17 @@ export class DebugService implements IDebugger {
     this._stoppedThreads.clear();
   }
 
+  /**
+   * Restarts the debugger.
+   * Precondition: isStarted() and stopped.
+   */
+  async restart(): Promise<void> {
+    await this.stop();
+    this.clearModel();
+    this._stoppedThreads.clear();
+    await this.start();
+  }
+
   /**
    * Restore the state of a debug session.
    * @param autoStart - when true, starts the debugger

src/tokens.ts

@@ -78,6 +78,12 @@ export interface IDebugger extends IDisposable {
    */
   stop(): Promise<void>;
 
+  /**
+   * Restart the debugger.
+   * Precondition: isStarted()
+   */
+  restart(): Promise<void>;
+
   /**
    * Restore the state of a debug session.
    * @param autoStart - when true, starts the debugger