In this sixth part of the salesforce DX series, In this post, I am going to explain how to migrate changes from the scratch org to salesforce sandbox for testing. When you’re ready to validate your source, convert your Salesforce DX source to Metadata API source format. You can then deploy to a sandbox.You can deploy or retrieve up to 10,000 files at once. The maximum size of the deployed or retrieved .zip file is 400 MB (39 MB compressed). If either limit is exceeded, the operation fails.You can increase the efficiency of your sandbox and production deployments by using tests you’ve already done in the scratch org. Run only the tests that are required, such as tests for Apex classes and triggers that change for the deployment. To run only specified tests when you deploy, set -l to RunSpecifiedTests and use -r to specify a comma-separated list of tests for deployment-specific changes to your Apex code.
sfdx force:mdapi:deploy -d mdapi_output_dir/ -u my-dev-sbx -l NoTestRun