From 8b92a34cd9ff8de7586c21a943a85b181c2ac048 Mon Sep 17 00:00:00 2001
From: Tim <mrtechguy234@gmail.com>
Date: Fri, 19 Jun 2020 18:08:29 -0400
Subject: [PATCH] fixed a bug

---
 src/client/datascience/export/exportBase.ts   | 27 +++++++++++++++++--
 .../export/exportManagerFileOpener.ts         | 14 +++++-----
 src/client/datascience/export/exportToHTML.ts |  2 +-
 3 files changed, 34 insertions(+), 9 deletions(-)

diff --git a/src/client/datascience/export/exportBase.ts b/src/client/datascience/export/exportBase.ts
index 50bbc1a9b474..7bf957085fed 100644
--- a/src/client/datascience/export/exportBase.ts
+++ b/src/client/datascience/export/exportBase.ts
@@ -21,12 +21,35 @@ export class ExportBase implements IExport {
     public async export(_source: Uri, _target: Uri): Promise<void> {}
 
     @reportAction(ReportableAction.PerformingExport)
-    public async executeCommand(source: Uri, args: string[]): Promise<void> {
+    public async executeCommand(source: Uri, target: Uri, args: string[]): Promise<void> {
         const service = await this.getExecutionService(source);
         if (!service) {
             return;
         }
-        await service.execModule('jupyter', ['nbconvert'].concat(args), { throwOnStdErr: false, encoding: 'utf8' });
+
+        const oldFileExists = await this.fileSystem.fileExists(target.fsPath);
+        let oldFileTime;
+        if (oldFileExists) {
+            oldFileTime = (await this.fileSystem.stat(target.fsPath)).mtime;
+        }
+
+        const result = await service.execModule('jupyter', ['nbconvert'].concat(args), {
+            throwOnStdErr: false,
+            encoding: 'utf8'
+        });
+
+        // Need to check if export failed, since throwOnStdErr is not an
+        // indicator of a failed export.
+        if (!(await this.fileSystem.fileExists(target.fsPath))) {
+            throw new Error(result.stderr);
+        } else if (oldFileExists) {
+            // If we exported to a file that already exists we need to check that
+            // this file was actually overriden during export
+            const newFileTime = (await this.fileSystem.stat(target.fsPath)).mtime;
+            if (newFileTime === oldFileTime) {
+                throw new Error(result.stderr);
+            }
+        }
     }
 
     protected async getExecutionService(source: Uri): Promise<IPythonExecutionService | undefined> {
diff --git a/src/client/datascience/export/exportManagerFileOpener.ts b/src/client/datascience/export/exportManagerFileOpener.ts
index 46ce79937709..7f5822883b1b 100644
--- a/src/client/datascience/export/exportManagerFileOpener.ts
+++ b/src/client/datascience/export/exportManagerFileOpener.ts
@@ -31,7 +31,7 @@ export class ExportManagerFileOpener implements IExportManager {
             uri = await this.manager.export(format, model);
         } catch (e) {
             traceError('Export failed', e);
-            await this.showExportFailed(e);
+            this.showExportFailed(e);
             sendTelemetryEvent(Telemetry.ExportNotebookAsFailed, undefined, { format: format });
             return;
         } finally {
@@ -68,11 +68,13 @@ export class ExportManagerFileOpener implements IExportManager {
         await this.documentManager.showTextDocument(doc);
     }
 
-    private async showExportFailed(msg: string) {
-        await this.applicationShell.showErrorMessage(
-            // tslint:disable-next-line: messages-must-be-localized
-            `${getLocString('DataScience.failedExportMessage', 'Export failed')} ${msg}`
-        );
+    private showExportFailed(msg: string) {
+        this.applicationShell
+            .showErrorMessage(
+                // tslint:disable-next-line: messages-must-be-localized
+                `${getLocString('DataScience.failedExportMessage', 'Export failed')} ${msg}`
+            )
+            .then();
     }
 
     private async askOpenFile(uri: Uri): Promise<boolean> {
diff --git a/src/client/datascience/export/exportToHTML.ts b/src/client/datascience/export/exportToHTML.ts
index 58c4d0987181..005addcc4cfc 100644
--- a/src/client/datascience/export/exportToHTML.ts
+++ b/src/client/datascience/export/exportToHTML.ts
@@ -15,6 +15,6 @@ export class ExportToHTML extends ExportBase {
             '--output-dir',
             path.dirname(target.fsPath)
         ];
-        await this.executeCommand(source, args);
+        await this.executeCommand(source, target, args);
     }
 }