You can test your current M2E Pro set up on Magento 2 and you don’t need to stop the synchronization process on your Magento v.1.
1) The first and major thing you need to do is to import your database tables dump from Magento v1.x to the Magento v2.x
When performing the test, there is no need to disable the Module and start the migration process via the Proceed button under the Migration tab. This will trigger the actual migration, not the test one.
2) The imported data will be adapted to the Magento v2.x environment. After tables are transferred, you will see Step 2 of the Migration Wizard.
3) Set Disable M1 Synchronization option to No to keep synchronization on Magento v1.x running. Click Continue.
4) On Step 3, set Enable M2 Synchronization option to No. Click Complete.
That’s it! Now you can explore Magento 2 functionality and check how your data was transferred.
To continue working with Magento 2, you will need to disable the synchronization process on your Magento v.1 and enable it for Magento v.2.
For that, go to System > Configuration > M2E Pro > Module & Channels > Module in Magento 1 and turn off Automatic Synchronization.
After that, in Magento 2 go to Stores > Settings > Configuration > M2E Pro > Advanced Settings > Module and enable Automatic Synchronization.
If you don't need to test Magento 2, you are welcome to proceed with the full Migration process. Check out our Migration Guide or a detailed video tutorial.