QB Issue Resolution:

Yes, there is a Developer Sandbox:

The Quickbooks Developer Sandbox help you build and test integration with QuickBooks, we provide you with a QuickBooks Online sandbox. It looks and acts just like your customers’ live QuickBooks companies do. You work with your sandbox while your app is in development mode, and not yet released to production.

http://developer.qbapi.com/Quickbooks-Developer-Sandbox.aspx

Resolution for Issue 'Is there a Quickbooks Developer Sandbox?' available: Yes (Solved).
Source: Intuit Community forum.

Is there a Quickbooks Developer Sandbox?: this issue or error code is a known issue in Quickbooks Online (QBO) and/or Quickbooks. Support for this issue is available either by self-service or paid support options. Experts are available to resolve your Quickbooks issue to ensure minimal downtime and continue running your business. First try to resolve the issue yourself by looking for a resolution described below. If it is a complex issue or you are unable to solve the issue, you may contact us by clicking here or by using other support options.

Support for Quickbooks Sandbox
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Error Recovery for Quickbooks Sandbox [Canada]
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