title: How to turn off parallel execution of tests for multi-project builds?
body: <p>I have a multi-project build with tests in sub-projects and in a parent project. The build is aggregated so that the parent project runs all tests in child projects.</p>
  
  <p>I configured it so that there's no parallel execution of tests in both the sub-projects and the parent project, via </p>
  
  <pre><code>parallelExecution in Test := false
  </code></pre>
  
  <p>However, I have the nagging feeling that tests that span over multiple projects are ran in parallel. In the case of one of the sub-projects this is a problem because it mutates state in a test database concurrently, leading to the test to fail.</p>
  
  <p>Any ideas as to how to globally switch of parallel execution of tests, between projects?</p>