fix(transaction): prevent rollback without connection (#9889)

lib/transaction.js

@@ -85,6 +85,10 @@ class Transaction {
       return Utils.Promise.reject(new Error('Transaction cannot be rolled back because it has been finished with state: ' + this.finished));
       return Utils.Promise.reject(new Error('Transaction cannot be rolled back because it has been finished with state: ' + this.finished));
     }
     }
 
 
+    if (!this.connection) {
+      return Promise.reject(new Error('Transaction cannot be rolled back because it never started'));
+    }
+
     this._clearCls();
     this._clearCls();
 
 
     return this
     return this

test/integration/transaction.test.js

@@ -161,6 +161,16 @@ if (current.dialect.supports.transactions) {
       ).to.eventually.be.rejected;
       ).to.eventually.be.rejected;
     });
     });
 
 
+    it('should not rollback if connection was not acquired', function() {
+      this.sinon.stub(this.sequelize.connectionManager, '_connect')
+        .returns(new Support.Sequelize.Promise(() => {}));
+
+      const transaction = new Transaction(this.sequelize);
+
+      return expect(transaction.rollback())
+        .to.eventually.be.rejectedWith('Transaction cannot be rolled back because it never started');
+    });
+
     it('does not allow queries immediatly after rollback call', function() {
     it('does not allow queries immediatly after rollback call', function() {
       const self = this;
       const self = this;
       return expect(
       return expect(