fix: missing await in rollback (#671)

samples/concepts.js

@@ -1102,15 +1102,15 @@ class Transaction extends TestHelper {
         const [task] = await transaction.get(taskKey);
         if (task) {
           // The task entity already exists.
-          transaction.rollback();
+          await transaction.rollback();
         } else {
           // Create the task entity.
           transaction.save(taskEntity);
           transaction.commit();
         }
         return taskEntity;
       } catch (err) {
-        transaction.rollback();
+        await transaction.rollback();
       }
     }
     // [END datastore_transactional_get_or_create]

samples/tasks.js

@@ -112,7 +112,7 @@ async function markDone(taskId) {
     await transaction.commit();
     console.log(`Task ${taskId} updated successfully.`);
   } catch (err) {
-    transaction.rollback();
+    await transaction.rollback();
   }
 }
 // [END datastore_update_entity]

samples/tasks.markdone.js

@@ -44,7 +44,7 @@ async function main(taskId) {
       await transaction.commit();
       console.log(`Task ${taskId} updated successfully.`);
     } catch (err) {
-      transaction.rollback();
+      await transaction.rollback();
       throw err;
     }
   }

src/request.ts

@@ -1301,7 +1301,13 @@ class DatastoreRequest {
     const transaction = this.datastore.transaction();
     transaction.run(async err => {
       if (err) {
-        transaction.rollback();
+        try {
+          await transaction.rollback();
+        } catch (error) {
+          // Provide the error & API response from the failed run to the user.
+          // Even a failed rollback should be transparent.
+          // RE: https://github.com/GoogleCloudPlatform/gcloud-node/pull/1369#discussion_r66833976
+        }
         callback!(err);
         return;
       }
@@ -1321,7 +1327,13 @@ class DatastoreRequest {
         const [response] = await transaction.commit();
         callback!(null, response);
       } catch (err) {
-        transaction.rollback();
+        try {
+          await transaction.rollback();
+        } catch (error) {
+          // Provide the error & API response from the failed commit to the user.
+          // Even a failed rollback should be transparent.
+          // RE: https://github.com/GoogleCloudPlatform/gcloud-node/pull/1369#discussion_r66833976
+        }
         callback!(err);
       }
     });

test/request.ts

@@ -2251,6 +2251,38 @@ describe('Request', () => {
         done();
       });
     });
+
+    it('should avoid the rollback exception in transaction.run', done => {
+      sandbox
+        .stub(transaction, 'run')
+        .callsFake((gaxOption, callback?: Function) => {
+          callback = typeof gaxOption === 'function' ? gaxOption : callback!;
+          callback(new Error('Error.'));
+        });
+
+      sandbox
+        .stub(transaction, 'rollback')
+        .rejects(new Error('Rollback Error.'));
+
+      request.merge({key, data: null}, (err: Error) => {
+        assert.strictEqual(err.message, 'Error.');
+        done();
+      });
+    });
+
+    it('should avoid the rollback exception in transaction.get/commit', done => {
+      sandbox.restore();
+      sandbox.stub(transaction, 'get').rejects(new Error('Error.'));
+
+      sandbox
+        .stub(transaction, 'rollback')
+        .rejects(new Error('Rollback Error.'));
+
+      request.merge({key, data: null}, (err: Error) => {
+        assert.strictEqual(err.message, 'Error.');
+        done();
+      });
+    });
   });
 
   describe('request_', () => {