We're running a CI process with the Force.com Migration tool and using <sf:deploy checkOnly="true" testLevel="RunLocalTests" ...>
The build times are climbing up there as we add more tests. Is there any way to enable parallel test execution? It seems like the metadata deploy is always serial. Would it require a deploy, test with tooling, undeploy?
Edit: Found this in the Force.com migration tool doc pg. 19 (https://resources.docs.salesforce.com/206/latest/en-us/sfdc/pdf/salesforce_migration_guide.pdf)
"Apex tests that run as part of a deployment always run synchronously and serially."
So it looks like it would be a deploy, run tests, undeploy org approach. Then I'm curious if anyone has done a successful undeploy.