title: Set default env variable for test configuration in sbt
body: <p>In my app i have runtime config initialization based on SCALA_ENV variable</p>
  
  <p>In build.sbt i need to check if SCALA_ENV var is set, and if not set it to "test" but only for tests configuration, so that when </p>
  
  <pre><code>sbt test
  </code></pre>
  
  <p>is run locally on a developer machine without explicitly setting SCALA_ENV it would always use test environment configs</p>
  
  <p>I tried </p>
  
  <pre><code>fork in test := true
  envVars in Test := Map("SCALA_ENV" -&gt; "test")
  </code></pre>
  
  <p>And then later somewhere in tests </p>
  
  <pre><code>System.getenv("SCALA_ENV")
  </code></pre>
  
  <p>But it always returns null...</p>