diff --git a/src/extension.ts b/src/extension.ts
index 5635a5ad..6a19f477 100644
--- a/src/extension.ts
+++ b/src/extension.ts
@@ -95,7 +95,6 @@ export async function activate(ctx: vscode.ExtensionContext) {
   watcher.onDidChange(changeHandler);
   watcher.onDidCreate(changeHandler);
   ctx.subscriptions.push(watcher);
-  await rebuildTests(controller);
   await genEnvFile(buildDir);
 
   // Refresh if the extension configuration is changed.
@@ -207,6 +206,8 @@ export async function activate(ctx: vscode.ExtensionContext) {
           break;
       }
     }
+  } else {
+    await rebuildTests(controller);
   }
 
   const downloadLanguageServer = extensionConfiguration(SettingsKey.downloadLanguageServer);