title: how to go test Multiple packages
body: <p>In my project, there are hundred packages. So where I run: </p>
  
  <pre><code>$(foreach i,$(TEST_PKGS),go test $(i) -test.short -v)
  </code></pre>
  
  <p>it will take almost a hour.
  If I run: <code>go test $(TEST_PKGS)</code>, it will cost a large memory.
  How to handle it this problem?</p>