title: Running a global test setup before each test in Jest
body: <p>I'm trying to have a test setup function executed before each single test in my Jest test suite. I know that I can use <code>beforeEach</code> to accomplish this within a single test file, but I want to do it globally for all my test files <strong>without</strong> having to explicitly modify each single file.</p>
  
  <p>I looked into the <a href="https://facebook.github.io/jest/docs/en/configuration.html" rel="noreferrer">jest configuration file</a>, and noticed a couple of configs that thought could have worked: <a href="https://facebook.github.io/jest/docs/en/configuration.html#globalsetup-string" rel="noreferrer"><code>globalSetup</code></a> and <a href="https://facebook.github.io/jest/docs/en/configuration.html#setupfiles-array" rel="noreferrer"><code>setupFiles</code></a>, but they seem to be run only once (at the very beginning of the test run). Like I said, I need it to be run before "each" <code>it</code> block in my test files.</p>
  
  <p>Is this possible?</p>