working copy - backup() is not optional anymore

src/vs/workbench/contrib/backup/common/backupTracker.ts

@@ -114,10 +114,6 @@ export abstract class BackupTracker extends Disposable {
 			return; // skip if auto save is enabled with a short delay
 		}
 
-		if (typeof workingCopy.backup !== 'function') {
-			return; // skip if working copy does not support backups
-		}
-
 		// Clear any running backup operation
 		dispose(this.pendingBackups.get(workingCopy));
 		this.pendingBackups.delete(workingCopy);
@@ -131,7 +127,7 @@ export abstract class BackupTracker extends Disposable {
 			this.pendingBackups.delete(workingCopy);
 
 			// Backup if dirty
-			if (workingCopy.isDirty() && typeof workingCopy.backup === 'function') {
+			if (workingCopy.isDirty()) {
 				this.logService.trace(`[backup tracker] running backup`, workingCopy.resource.toString());
 
 				const backup = await workingCopy.backup();

src/vs/workbench/contrib/backup/electron-browser/backupTracker.ts

@@ -161,12 +161,10 @@ export class NativeBackupTracker extends BackupTracker implements IWorkbenchCont
 
 				// Backup does not exist
 				else {
-					if (typeof workingCopy.backup === 'function') {
-						const backup = await workingCopy.backup();
-						await this.backupFileService.backup(workingCopy.resource, backup.content, contentVersion, backup.meta);
+					const backup = await workingCopy.backup();
+					await this.backupFileService.backup(workingCopy.resource, backup.content, contentVersion, backup.meta);
 
-						backups.push(workingCopy);
-					}
+					backups.push(workingCopy);
 				}
 			}));
 		}

src/vs/workbench/services/workingCopy/common/workingCopyService.ts

@@ -42,10 +42,20 @@ export interface IWorkingCopyBackup {
 
 export interface IWorkingCopy {
 
+	/**
+	 * The unique resource of the working copy. There can only be one
+	 * working copy in the system with the same URI.
+	 */
 	readonly resource: URI;
 
+	/**
+	 * Human readable name of the working copy.
+	 */
 	readonly name: string;
 
+	/**
+	 * The capabilities of the working copy.
+	 */
 	readonly capabilities: WorkingCopyCapabilities;
 
 
@@ -83,14 +93,21 @@ export interface IWorkingCopy {
 	 *
 	 * Providers of working copies should use `IBackupFileService.resolve(workingCopy.resource)`
 	 * to retrieve the backup metadata associated when loading the working copy.
-	 *
-	 * Not providing this method from the working copy will disable any
-	 * backups and hot-exit functionality for those working copies.
 	 */
-	backup?(): Promise<IWorkingCopyBackup>;
+	backup(): Promise<IWorkingCopyBackup>;
 
+	/**
+	 * Asks the working copy to save. If the working copy was dirty, it is
+	 * expected to be non-dirty after this operation has finished.
+	 *
+	 * @returns `true` if the operation was successful and `false` otherwise.
+	 */
 	save(options?: ISaveOptions): Promise<boolean>;
 
+	/**
+	 * Asks the working copy to revert. If the working copy was dirty, it is
+	 * expected to be non-dirty after this operation has finished.
+	 */
 	revert(options?: IRevertOptions): Promise<void>;
 
 	//#endregion